Quest for the Compositional identification andChemical evolutional understanding of the interstellar carbonaceous dust
based on the experiment using JEM/ExHAM on the ISS
I. Sakon,1 T. Onaka,1 Y. Kimura,2 S. Kimura,3 M. Nakamura,4 A. Ichimura,5 and S. Wada3
1Department of Astronomy, Graduate School of Science, University of Tokyo, Japan
2Institute of Low Temperature Science, Hokkaido University, Japan
3Coordinated Center for UEC Research Facilities, The University of Electro-Communication,Japan
4Collage of Science and Technology, Nihon University, Japan
5Institute of Space and Astronautical Science, JAXA, Japan

The primordial form of cosmic solid is produced as a result of the dust/molecular nucleation in
the stellar gas wind ejected from the evolved stars and is denatured in the circumstellar
environment to become the member of the interstellar dust. However, the true compositional
identification of cosmic carbonaceous dust grains has not been made successfully and, as aconsequence, the evolutionary processes of interstellar dust in galaxies are not fully understood.
Laboratory approaches have played an important role in providing observational astronomers
accurate knowledge to derive the compositional, chemical, and physical properties of interstellar
dust from the observed infrared spectrum of various astrophysical sources. In many cases,
however, the dust particles that we treat in the laboratory are not always identical to the actualinterstellar dust and, therefore, the attempts to identify the physical/chemical processes thatassociate the laboratory-synthesized dust with the actual interstellar dust are highly in demand.
We have proposed an experimental investigation program using JEM/ExHAM on theInternational Space Station (ISS) aiming to obtain accurate knowledge on the compositional,
chemical and physical properties of interstellar dust. In this program, several laboratorysynthesized carbonaceous compounds including quenched carbonaceous composites (QCCs;
Sakata et al. 1983) and nitrogen-bearing hydrocarbons, which are the valid candidates ofprimordial carbonaceous dust condensed in the AGB stellar ejecta, are planned to be brought
and exposed to the cosmic environment at ISS orbit for ~1 year by means of JEM/ExHAM.
The primary goal of this project is to identify the true carriers of the unidentified infrared (UIR)bands (e.g., Gillett et al. 1973) and those of the 2175Å interstellar extinction bump (Stecher1965). In this presentation, we introduce the current status of our exposure experiment program
titled "Quest for the Compositional identification and Chemical evolutional understanding of theInterstellar Carbonaceous Dust based on the experiment using JEM/ExHAM on the ISS".
References
[1]
[2]
[3]

A. Sakata et al. 1983, Nature, 301, 493
F.C.Gillett, W.J.Forrest, and K.M.Merrill 1973, The Astrophysical Journal, 183, 87-93
T. P. Stecher, 1965, The Astrophysical Journal, 142, 1683

Chemicall Evolution of N-beariing Organic Moleculees Leading tto Glycine
1,4
M. OhishiO, T. Hirota,2,4 M
M. Saito3,4, T. Suzuki4,1, and N. K
Kaifu1
1

Asstronomy Daata Center, NAOJ, Jap
pan,
Mizu
usawa VLBII Observato
ory, NAOJ, JapanJ
3
Nobeeyama Radioo Observato
ory, NAOJ, Japan
4
Graduaate Universiity for Adva
anced Studiees, Japan2

It is wiidely acceppted that prrebiotic cheemical evollution fromm small to large and complex
moleculles would have resultted in the Origin of Life. On thet other hhand there are two
conflictting views wherew
inorg
ganic formattion of com
mplex organiic moleculees (hereafterr COMs)
occurredd in the earrly Earth, ono the Earthh or out of the Earth. EhrenfreundEd et al.[1] indicatedthat exoogenous deelivery of COMs
C
by ccomets and//or asteroid
ds to the eaarly Earth couldcbelarger thhan their terrrestrial forrmation by tthree orderss of magnitu
ude. If aminno acids aree formed
in intersstellar clouuds, significant amountt of them may
m be delivered to pllanets. Deteection ofamino aacids wouldd accelerate the discussiion concern
ning the univ
versality off “life”.
t simplesst amino accid, glycine (NH2CH2C
COOH), weere madeSo far, many trialss to detect theh-mass form
ming regionns, but nonee of them wwere successsful. One
towardss Sgr B2 annd other highidea to overcome this situatio
on would bbe to searchh for precurrsors to glyycine. Althoough thechemicaal evolutionn of interstellar N-beariing COMs is poorly kn
nown, methhylamine (CCH3NH2)is propoosed as one precursor tot glycine. CH3NH2 caan be formeed from abuundant species, CH4
and NHH3, on icy duust surface. Further meethyleneiminne (CH2NH
H) would bee related to CH
C 3NH2[22][3]. Anotther possiblle route too form CH
H3NH2 ishyydrogenatio
on to HCN on dust suurface [4][55]: HCN→ CH2NH→→ CH3NH2. Figure 1 shows a possible
foormation rooute to gly
ycine, which
ch is basedd on thelaaboratory stu
udies mentiioned abovee.
Fig.1

A Possible Formation Route to Gllycine

In the ppast CH2NH
H was repo
orted only inn Sgr B2, W51,W
Orionn KL, and G34.3+0.15
5 [2]. In
April 20013, we exxtended this survey by using the NobeyamaN
45 m radioo telescope towards
CH3OH
H-rich sourcces. We su
ucceeded too detect four
fo new CH
C 2NH souurces. The derived
fractionnal abundannces of CH2NH relativee to H2 are as high as 6x10-8, impplying that CH2NH
may exiist widely inn the ISM [66].
If this iis the case, further hyddrogenationn would effficiently pro
oduce CH3N
NH2. Basedd on thisidea wee conductedd a survey ofo CH3NH2 towards CH
H2NH-rich sources in the spring of 2014,
and succeeded to detectd
CH3NH
N 2 towardss two sourcces. The estiimated fracttional abundance of-8
CH3NH
H2 to H2 was ~ 10 , abbout 10 tim
mes higher th
han the valu
ue reportedd towards SgrB2(N)[7].
Since itt is well knoown that CO
O2 exists in most of moolecular clouuds, CH3NH
H2 could bee a direct
H3NH2-rich sources wo
ould turnprecursoor candidatee to glycinee – the simpplest amino acid— , CH
into proomising glyycine targets by ALM
MA. Such studiesswou
uld also acccelerate discussion
regardinng the exoggenous deliv
very of prebbiotic speciies to planets and connnection betw
ween the
Universse and life.

References:[1] Ehrenfreund et al. Rep. Prog. Phys., 65, 1427, 2002
[2] Holtom et al., ApJ, 626, 940, 2005
[3] Kim & Kaiser et al. ApJ, 729:68, 2011[4] Dickens et al., ApJ, 479, 307, 1997
[5] Theule et al., 2011, A& A, 534, A64[6] Suzuki et al., 2014, this workshop[7] Halfen et al., ApJ, 767, id.66

Chemical / Physical Properties of CH2NH Sources
T. Suzuki,1 T. M. Ohishi1 ,Hirota,2 and Saito Masao3
1

Astronomy Data Center, NAOJ, Japan
Mizusawa VLBI Observatory, NAOJ, Japan
3
Nobeyama Radio Observatory, NAOJ, Japan
2

Despite its importance for the Origin of Life, long lasting challenges to detect interstellar
simplest amino acid, glycine (NH2CH2COOH) were not successful. Since precursor-richsources would be potential glycine-rich sources, understanding the chemistry of its precursors
will lead a breakthrough of future glycine surveys with ALMA. For the formation mechanism,
laboratory experiments demonstrated that dust surface reactions could form glycine. This
process start with the hydrogenation (H added) to HCN : HCN → CH2NH (Methylenimine)→
CH3NH2 (Methylamine) (Theule et al. (2011)), similar to well known formation process of
CH3OH: CO→H2CO→CH3OH. After that, reaction of CH3NH2 with CO2 will form glycine(Kim & Kaiser (2011)). However, precursors of glycine, CH2NH and CH3NH2, were also notwell investigated in the actual interstellar medium.
Since 2013 April, we have conducted survey observations of CH2NH using NRO 45m
telescope towards 11 high-mass and three low-mass star-forming regions. As a result, CH2NH
was detected in eight sources, including four new ones. Among them, G10.47+0.03 andG31.41+0.3 showed especially high CH2NH abundance.
The chemical properties of CH2NH sources give us clues to reveal the CH2NH chemistry. The
positive correlations between “CH2NH vs CH3OH” and “CH2NH vs HC15N” would suggestthat hydrogenation to HCN is plausible way to form CH2NH in the actual interstellar medium.
Further, other complex N-bearing species, like C2H5CN and C2H3CN also tend to be higher inCH2NH-rich sources, while non N-bearing species does not show this trend (figure 1). Suchchemical properties might be linked to the evolutional phase and/or initial condition of starformation. In this work shop, we will show our results and would like to discuss theconnection between physical and chemical properties of CH2NH-rich sources.

Figure 1: Comparison of fractional abundances among complex organic species

References[1] Kim & Kaiser. ApJ, 729:68[2] Theule et al., 2011, A& A, 534, A64

Chemical Evolution of Star-Forming Cores toward Protostellar/planetary Disks
N. Sakai,1 & S. Yamamoto1
1

Department of Physics, The University of Tokyo, Japan

In the last decade, it is clearly demonstrated that low-mass protostellar cores harbor various
complex organic molecules (COMs) in the vicinity of the protostar. This result attracted
much attention of astronomers and planetary scientists in relation to the origin of pre-solarorganic materials found in meteorites and comets. In the course of these studies, significant
chemical diversity was recognized among the observed sources. Now, we know at least two
distinct families in chemical compositions; one is a hot corino characterized by abundantsaturated COMs such as HCOOCH3, (CH3)2O, and C2H5CN [e.g. 1], whereas the other is a
warm-carbon-chain-chemistry (WCCC) source characterized by abundant unsaturated COMs
such as carbon-chain molecules and their related molecules [e.g. 2]. The chemical diversity
would originate from the different duration time of the starless core phase, although a larger,
statistically significant, sample is needed to confirm this prediction. On the other hand, themost interesting issue to be studied is how the chemical diversity in the Class 0 stage isbrought into the later stages toward protoplanetary disks. Fortunately, such a study is now
feasible with high-sensitivity and high-angular-resolution capabilities of ALMA. In this talk,I will present recent chemical studies on disk formation done by ALMA [e.g. 3-5].

References[1] S. Cazaux, A. G. G. M. Tielens, C. Ceccarelli, A. Castets, V. Wakelam, E. Caux, B. Parise, & D. Teyssier,
2003, ApJ, 593, L51.
[2] N. Sakai & S. Yamamoto, 2013, Chem. Rev. 113, 8981.
[3] N. Sakai et al. 2014, Nature, 507, 78.
[4] N. Sakai et al. 2014, ApJ, 791, L38.
[5] Y. Oya et al. 2014, ApJ, 795, in press.

The origin of complex organic molecules in prestellar cores.
C. Vastel,1 B.Lefloch,2 and C. Ceccarelli2,3
1

Université de Toulouse, UPS-OMP, IRAP, Toulouse, France
2
Univ. Grenoble Alpes, IPAG, F-38000 Grenoble, France

Complex organic molecules (COMs) have been detected in a variety of environments,
including cold prestellar cores. Given the low temperature of these objects, these lastdetections challenge existing models. We report here new observations towards the prestellar
core L1544, based on an unbiased spectral survey of the 3mm band at the IRAM-30m
telescope, as part of the Large Program ASAI. The observations allow us to provide the full
census of the oxygen bearing COMs in this source and to derive their abundance. The nonLTE analysis of the methanol lines shows that they are likely emitted at the border of the core,in the same region layer where H2O was detected by the Herschel space mission
We discuss the origin of this emission and propose that a non-thermal desorption mechanism
is also responsible for the observed emission of methanol and COMs. We find that thedesorbed oxygen and a tiny amount of desorbed methanol and ethane are enough to reproduce
the abundances of COMs measured in L1544.
These new findings open the possibility that COMs in prestellar cores originate in a similarouter layer rather than in the dense inner cores, as previously assumed, and that theirformation is driven by the non-thermally desorbed species.

Formamide (NH2CHO) in star-forming regions: A crucial precursor of prebiotic
material
A. López-Sepulcre,1,2,3 E. Mendoza4, B. Lefloch,2,3 C. Ceccarelli2,3, R. Bachiller5, and theASAI team1

Dep. Physics, University of Tokyo, Japan
Université Grenoble Alpes, IPAG, France
3
CNRS, IPAG, France
4
Observatório do Valongo, Universidade Federal Rio de Janeiro, Brasil
5IGN,
Observatorio Astronómico Nacional, Spain
2

Understanding the origin of life on Earth represents one of the hot topics in modern science.
One of the big questions is whether the original mechanism that led from simple molecules tolife was connected to metabolism or to genetics, both intimately linked in living beings.
Formamide (NH2CHO) contains the four most important elements for biological systems, andit has recently been proposed as a prebiotic precursor of both metabolic and genetic material,suggesting a common chemical origin for the two mechanisms [1].
Even though formamide was first detected in molecular clouds in 1971 [2], dedicated studies
have started only very recently, as its potential as a key prebiotic molecule has become moreevident. These studies report the presence of formamide in massive hot molecular cores [3,4],
one low-mass protostar [5], and the comet Hale-Bopp [6]. In the past months, the IRAM
Large Program ASAI, dedicated to astrochemical studies of star-forming regions, hasrevealed new discoveries of NH2CHO [7], including its detection, for the first time, in outflow
shock spots [8]. The presence of formamide in such a variety of star-forming environments, aswell as on a Solar System comet, suggests that it could have been exogenously delivered ontoa young Earth in the past.
In this contribution, we will present our new ASAI results on formamide, and compare themto previous studies, to try to understand its formation mechanisms in the interstellar medium.
We will discuss the different chemical pathways that have been proposed, which include
gas-phase as well as gas-grain reactions, and we will explain why we favor the latter. Lastly,
we will emphasize the importance of joining efforts with experts on both theoretical andexperimental chemistry in order to make progress.

Figure 1: Some of the NH2CHO lines detected in the intermediate-mass star-forming region OMC-2 FIR 4.

References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]

Saladino, R., Botta, G., Pino, S., Costanzo, G., Di Mauro, E. 2012, CSRv, 41, 5526.
Rubin, R. H., Swenson, G. W., Jr., Benson, R. C., Tigelaar, H. L., Flygare, W. H. 1971, ApJ, 169, 39.
Adande, G.R., Woolf, N.J., G., Ziurys, L.M. 2011, Astrobiology, 13, 439.
Bisschop, S. E., Jørgensen, J. K., van Dishoeck, E. F., de Wachter, E. B. M. 2007, A&A, 465, 913.
Kahane, C., Ceccarelli, C., Faure, A., Caux, E. 2013, ApJ, 763, L38.
Bockelée-Morvan, D., Lis, D. C., Wink, J. E. et al. 2000, A&A, 53, 1101.
López-Sepulcre, A., Mendoza, E., Lefloch, B. et al. (in prep.).
Mendoza, E., Lefloch, B., López-Sepulcre, A. et al. 2014, MNRAS (in press).

Volatiles in protoplanetary disks - setting the stage for planetary atmospheres
K. M. Pontoppidan,1 A. Banzatti,1 and S. Blevins1
1

Space Telescope Science Institute, Baltimore, MD 21218, USA

Volatile molecules are the main condensible carriers of the elements essential for life; carbon,hydrogen and nitrogen. Their chemical evolution during star and planet formation determines
the compositions of planets, including those destined to orbit in a habitable zone. The
composition of our own solar system has been mapped in great detail, and we are now
beginning to obtain direct measurements of the compositions of exoplanetary systems [1].
Since planetary compositions are ultimately driven by chemical and dynamical processes in
the protoplanetary and debris disk phases, we aim to understand the early evolution ofvolatiles in protoplanetary disks. However, the path from the interstellar medium to planets is
one fraught with complexity and twists, making it very difficult to derive purely theoreticalpredictions for chemistry. Direct observations of bulk molecular abundances are therefore
critical for answering the question of how chemically common the Earth is among exoplanets[2,3].
In the past few years, great observational strides have been made, in particular in measuring
the molecular composition in protoplanetary disks across the planet-forming regions from 1 to
10s of AU. I will review our current understanding of volatiles in protoplanetary disks andpresent recent observational work that demonstrates strong chemical evolution between theinterstellar medium and planet-forming material [4], and I will discuss why this is importantfor our understanding of exoplanet composition and habitability.
References
[1]
[2]
[3]
[4]

Madhusudhan 2012, 758, 36
Oberg et al. 2011, ApJ, 743, 16
Pontoppidan et al. 2014, Protostars & Planets VI, in press
Pontoppidan and Blevins 2014, Faraday Discussions 168, 49

The N2H+ ring in Protoplanetary Disks
Yuri Aikawa,1 Kenji Furuya,2 Hideko Nomura3 and Chunhua Qi4
1

Department of Earth and Planetary Sciences, Kobe University, Japan
2
Leiden Observatory, Netherland (JSPS Fellow)
3
Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Japan
4
Center for Astrophysics, USA

We investigate the chemistry of ion molecules in protoplanetary disks, motivated by thedetection of N2H+ ring around TW Hya[1]. While the observed ring coincides with the COsnow line, it is not apparent why N2H+ is abundant outside the CO snow line, because thesublimation temperature of N2, the mother molecule of N2H+, is similar to that of CO. We
reproduced a ring of N2H+ in a disk model with mm grains, but not in a model with ISM dust.
In the former, the ring is formed by a combination of the CO sink and photo-reactions, which
prevent the N2 sink. We also derived analytical formulas of molecular ion abundances asfunctions of density, ionization rate and abundances of major neutral molecules. The formulas
are useful in constraining the ionization rate and also abundances of major molecules, such as
CO and N2, from the observations. Using the analytical formulas, we show that without theCO sink effect, N2H+ ring is reproduced only if the sublimation temperature of N2 is lower
than that of CO. We also found that in the model without the sink effect, N2H+ exists mostly
in the disk midplane, while in the model with CO sink, N2H+ is abundant in the layer relocatedfrom the midplane. In the former case, the N2H+ abundance would depend also on whether
cosmic-ray can reach the disk midplane[2].

References[1]
Qi, C, Oberg, K. I., Wilner, D. J., D'Alessio, P., Bergin, E.A., Andrews, S. M., Blake, G. A., Hogerheijde,
M. R., van Dishoeck, E. F. 2013, Science, 341, 6146
[2]
Aikawa, Y. et al. in prepIn-situ observation of ices by ultrahigh vacuum transmission electron microscope
and atomic force microscope
A. Kouchi,1 H. Hidaka,1 Y. Kimura,1 T. Hama,1 and N. Watanabe1
1Institute of Low Temperature Science/Hokkaido University, Japan

The importance of H2O ice, both amorphous and crystalline phases, at low temperatures has
been widely realized not only for the formation and evolution of ices but also for
substrates of surface reactions. A vapor-deposited amorphous H2O ice (amorphous solid
water, ASW) have been studied extensively as an analogue of amorphous ices in molecular
clouds. ASWs deposited at around 10 K and deposited or annealed at temperatures higher
than 70 K are acknowledged to be high-density and low-density forms, respectively, fromelectron diffraction patterns [1]. However, much more problems remain to be solved.
Meanwhile, ASW deposited at around 10 K is considered to very porous from themeasurements of surface area and bulk density, and ASW deposited or annealed attemperatures higher than 70 K has been assumed to be compact (not porous). Although theimportance of surface structure of ASW has been implicitly realized, there has been no
direct observation of surface structure. In the studies of surface reactions, ASW is treated as“black box” at present. It is therefore highly desirable to investigate the structure andsurface structure of ASW by direct methods.
We have developed an ultrahigh vacuum (UHV) transmission electron microscope (TEM)
and an atomic force microscope (AFM) for in-situ observation of ASWs and ice crystals. In
the workshop, we will present preliminary results on the following topics: 1) Surface
structure of ASW, and 2) Novel method for the formation of high-density amorphous ice.

Figure 1: UHV-TEM (left) and UHV-AFM (right).

References[1]

P. Jenniskens & D. F. Blake, 1996, Science 265, 753.

Oxygen chemistry on dust grains
G. Vidali,1 J.He1,2
1

2

Physics Department, Syracuse University, USA
Current address: Chemistry Department, University of Hawai’i at Manoa, USA

Oxygen, the third most abundant element in space, intervenes in the formation of many
molecular species, some of which are important in the generation of molecules relevant to theemergence of life. The realization that many gas-phase processes are insufficient to justify theabundance of some of these molecules has led to laboratory studies of the formation ofmolecules, such as H2O, CO2, and others) on the surface of dust grain analogs in simulated ISM
conditions1,2.
As these surface processes rely on the residence time and diffusion of reactants, we devised a
combination of experiments and theoretical simulations to obtain desorption energy and energy
barriers for diffusion of oxygen atoms and of important oxygen-containing molecules3.
Here we present the results of recent experiments and simulations of the interaction of oxygenwith surfaces of amorphous silicates and amorphous water ice4. We also report on the formationof water on warm grains5, i.e., grains that are present at the edge of molecular clouds or ofphotodissociation regions, and on the formation of precursors of biogenic molecules6.

Figure 1: TPD traces of mass 16, 32, and 48 amu after depositing 8 minute O/O2 at 48 K on porous amorphouswater ice. The heating ramp is 10 K/minute. From Ref. 4.

This work is partially supported by NSF Astronomy & Astrophysics Grant No.1311958.
References
[1]
[2]
[3]

G.Vidali, 2013, J. Low Temp. Phys., 170, 1.
T. Hama & N.Watanabe, 2013, Chem. Rev. 113, 8783.

[4]

J.He & G.Vidali:, 2014, Faraday Discuss. 168, 5.
J.He, J.Shi, T.Hopkins, G.Vidali & M.Kaufman, 2014, in preparation.

[5]
[6]

J.He & G.Vidali, 2014, Astrophys.J., 788, 50.
J.He, G.Vidali, J.L.Lemaire, & R.Garrod, 2014, Astrophys. J., submitted.

Photodesorption of CO ice induced by a non-monochromatic light source
Yu-Jung Chen,1,2 Ko-Ju Chuang,1 Guillermo M. Muñoz Caro,3 Michel Nuevo,4,5
Ching-Chi Chu,1 Tai-Sone Yih,1 Wing H. Ip,6 and C.-Y. Robert Wu2
1

Department of Physics, National Central University, Taiwan
Space Sciences Center and Department of Physics and Astronomy, University of Southern
California, USA
3
Centro de Astrobiología, INTA-CSIC, Spain
4
NASA Ames Research Center, USA
5
BAER Institute, USA
6
Graduate Institute of Astronomy, National Central University, Taiwan
2

The microwave-discharge hydrogen-flow lamp (MDHL) provides hydrogen Lyman α (H Lyα, 121.6 nm) and H2 molecular emission in the 110–180 nm range. We show that the spectral
characteristics of the VUV light emitted in this range, in particular the relative proportion of
Lyman α to molecular emission bands, strongly depend on the pressure of H2 inside the lamp,
the lamp geometry (F type vs. T type), the gas used (pure H2 vs. H2 seeded in He), and theoptical property of the window used (MgF2 vs. CaF2). These different experimental
configurations of the MDHL are then used to study the VUV irradiation of CO ice at 14 K.
Experimental results show that the processes induced by photons in CO ice from a broad
energy range are different and more complex than the sum of individual processes induced bymonochromatic sources scanning the same energy range, due to the existence of multi-stateelectronic transitions and discrepancy of absorption cross-section between parent moleculesand products in Ly-α and H2 molecular emission ranges.

Figure 1: Photodesorbed column density of CO ice irradiated by the MDHL in several operating conditions
as a function of the photon dose, derived after taking the column densities of photodepletion CO andphotoproduced CO2 into account.

References[1][2]

Muñoz Caro, G. M., Jiménez-Escobar, A., Martin-Gago, J. A., et al. 2010, A&A, 522, A108
Chen, Y.-J., Chuang, K.-J., Muñoz Caro, G. M., et al. 2014, ApJ, 781, 15

Probing the Formation of Biorelvant Molecules in Kuiper Belts by Tunable Vacuum
Ultraviolet Photoionization Mass Spectrometry (PI-TOF-MS)
R.I Kaiser & B.M. Jones
Department of Chemistry & W.M. Keck Research Laboratory in Astrochemistry
University of Hawaii at Manoa, Honolulu, HI 96822, USA
During the last decade, Kuiper Belt Objects (KBOs) emerged in their role as a repositoryof primitive planetary material on Earth and are dubbed ‘primordial fossils’ helping tounderstand the origin and astrobiological evolution of the Solar System. Using a novelsurface scattering machine1, we simulate the interaction of ionizing radiation with KBO
analog ices and apply these findings to elucidate the formation of key classes ofbiorelevant molecules2-3 (amino acids, dipeptides, sugars, fatty acids, RNAnitrogen-bases). First, we mimic the space environment under clean, contamination-free
conditions at ultra-high vacuum (10-11 torr). Second, this setup allows a simulation of theinteraction of ionizing radiation with surfaces systematically over a wide range of KBO
relevant chemical and physical parameters in the same machine: i) the chemicalcomposition of the ices [methane (CH4), water (H2O), nitrogen (N2), carbon monoxide(CO), methanol (CH3OH)], ii) ice temperatures 30-50 K, and iii) ionizing radiation in theform of 1 keV protons and 10.2 eV photons (Lyman α) simulating the most significant
component of Solar Wind ions and photons interacting with KBO surfaces. Third, weinterface four complementary detection schemes to a single machine to probe individual
biorelevant molecules on line and in situ. This enables us to identify key functionalgroups in the ices via infrared (IR), Raman (Ra), and ultraviolet-visual (UV-VIS)
spectroscopy. Individual molecules subliming into the gas phase upon warm-up of thesamples can be identified via fragment-free reflectron time-of-flight mass spectrometry(ReTOF) coupled with vacuum ultraviolet (VUV) soft photoionization (ReTOF-PI). This
technique has the unique power to identify the molecules based on a cross correlation of
their mass-to-charge ratios, their ionization energies (IE), and photoionization efficiency
curves (PIE) ultimately unraveling an inventory of individual biorelevant molecules
formed upon interaction of ionizing radiation and KBO analog ices and also theirinterstellar precursors.
(1) Jones, B. M.; Kaiser, R. I., Application of Reflectron Time‐of‐Flight Mass Spectroscopy in the
Analysis of Astrophysically Relevant Ices Exposed to Ionization Radiation: Methane (CH4) andD4‐Methane (CD4) as a Case Study. The Journal of Physical Chemistry Letters 2013, 4 (11), 1965‐1971.
(2) Kaiser, R. I.; Maity, S.; Jones, B. M., Infrared and reflectron time‐of‐flight mass spectroscopic
analysis of methane (CH4)‐carbon monoxide (CO) ices exposed to ionization radiation ‐ toward theformation of carbonyl‐bearing molecules in extraterrestrial ices. Physical Chemistry Chemical Physics
2014, 16 (8), 3399‐3424.
(3) Maity, S.; Kaiser, R. I.; Jones, B. M., Infrared and Reflectron Time‐of‐Flight Mass Spectroscopic
Study on the Synthesis of Glycolaldehyde in Methanol (CH3OH) and Methanol‐Carbon Monoxide(CH3OH‐CO) Ices Exposed to Ionization Radiation. Faraday Discuss. 2014, 168 (1), 485‐516.

Astrochemistry in ion traps: from cold hydrogen to hot carbon
Dieter Gerlich
Department of Physics, Technische Universität Chemnitz, Germany
Astrochemistry deals with the formation and destruction of matter in very different environments including the early universe, cold dense interstellar clouds, hot circumstellar regions, orplanetary atmospheres. In this contribution I summarize our recent experimental activities inthis field using radio frequency (rf) traps for confining ions and nanoparticles. Two electrodearrangements are shown in Figure 1. The cryogenic 22-pole is meanwhile a very common ion
trap used for reaction dynamics and spectroscopy (see [1] and references therein), while thesplit ring electrode trap (SRET) has been developed for high temperature applications [2].
With closed cycle refrigerators, wall temperatures of 2.6 K have been achieved [3] while heating an C60+ ensemble with a CW CO2 laser has resulted in temperatures above 2000 K [2].

Figure 1: Left: 22pole ion trap for studying the interaction between cold stored ions and a beam of neutrals.
Right: Special quadrupole trap for monitoring hot particles via their black body radiation (BBR).

Many gas phase processes involving ions have been studied in rf traps, including bi- and termolecular reactions, radiative association, clustering, isomerization, and isotope fractionation.
In this talk, I will mention a few examples: (i) Associative detachment in H– + H collisions
measured in the temperature range between 10 and 135 K. (ii) So far unexplained is the experimental result that CH+(v=0,J) does not react with H atoms for J = 0 at low temperatures,
although the reaction is exothermic. (iii) In contrast to simple expectations, radiative association of H+ colliding with H2(J) is a factor of 2 slower for J = 0 than for J = 1. (iv) For reactions of N+(3Pja) with H2(J), first state specific rate coefficients k(J, ja) have been derived [1].
There are many innovative activities based on the combination of lasers and ion traps [4]. A
powerful new instrument used a cryogenic wire quadrupole and tunable IR lasers [3]. Veryversatile is the new spectroscopy method called Laser Induced Inhibition of Complex Growth(LIICG) which has been developed in Basel [5] for studying candidates for the diffuse interstellar bands (e.g. C60+). This method has been applied first to N2+ ions and extended in Köln
to CH5+ and H3+. As an example for measuring the stability of objects in a high temperature
stationary state, the decay rates of a cloud of C60+ ions also will be mentioned [2].
References
[1]
[2]
[3]
[4]
[5]

I. Zymak, M. Hejduk, D. Mulin, R. Plašil, J. Glosík, D. Gerlich, 2013, Ap.J. 768, 86.
D. Gerlich, S. Decker, 2014, Appl. Phys. B, 114, 257.
J. Jašík, J. Žabka, J. Roithová, and D. Gerlich, 2013, Int. J. Mass Spectrom. 354-355, 204.
For more information and references see https://www.tu-chemnitz.de/physik/ION
S. Chakrabarty, M.Holz, E.K. Campbell, A. Banerjee, D. Gerlich, and J. Maier, 2013, JPC Lett 4, 4051.

Formation of hydrated-alumina clusters
toward elucidation of chemical processes on mineral surfaces
M. Arakawa, K. Kohara, and A. Terasaki
Department of Chemistry, Kyushu University, Japan
Small particles consisting of ice, minerals, and organic molecules exist in the early stage ofplanetary formation. It is a prevalent hypothesis that, in protoplanetary nebulae, organic
molecules are formed through catalytic reactions on mineral particles. To investigate
essential reaction steps of the organic-molecule formation, size-selected clusters of mineralcomposition can be used as models for chemistry on mineral surfaces. As a first step, weinvestigated generation of mineral-composition clusters by focusing on compounds ofaluminum, whose elemental abundance is relatively high in the earth and in space.
Aluminum is known as a reactive metal as we can imagine from the fact that it is readilyoxidized by O2 and/or H2O in the air to form a passive surface. We have reported thataluminum-cluster cations, AlN+, react with a H2O molecule to form AlNO+, which implies H2generation [1]. In the present study, we investigated reaction of AlN+ with a mixture of O2
and H2O gases to observe formation of clusters with composition of aluminum minerals
abundant naturally.
In the experiment, AlN+ (N = 1–14) were generated by a magnetron-sputter cluster-ion source.
They were mass-selected and guided into a reaction cell filled with a buffer He gas containing
H2O and O2. The ions produced by the reaction of AlN+ with H2O and O2 were identified bya quadrupole mass analyzer.
Reaction products with a mass of 157 and 175 amu were observed for all the sizes except N =1. Since only Al+ was found to be inert, we speculated that these products originate from
Al2+, which is produced by dissociation of AlN+ (N ≥ 3). By controlling the partial pressuresof O2 and H2O, reaction intermediates such as Al2O+, Al2O3+, Al2O4H3+, and Al2O5H5+ wereobserved, and the prominent products were assigned to be Al2O6H7+ and Al2O7H9+ for 157
and 175 amu, respectively. The chemical composition of these products, Al2O3(H2O)nH+, issimilar to that of hydrated alumina such as boehmite, diaspore, and gibbsite except for theexcess proton.
To obtain structural information of these products, we performed
collision-induced dissociation experiment of Al2O6H7+ (157 amu) with an Ar gas, where
products of 139 and 121 amu were observed. The prominent product of 157 amu was thus
identified as Al2O4H3(H2O)2+ with two H2O molecules remaining intact.
We further investigated formation processes of these protonated hydrated-alumina clusters byobserving the reaction steps to model reactions of aluminum in natural environments; eachreaction intermediate was generated in the cluster source, and reaction with either H2O or O2
was examined in a step-by-step manner. It was found that reaction of aluminum with O2 andH2O to form alumina, Al2O3, at initial steps is followed by successive hydroxylation andhydration reactions.

References[1]

M. Arakawa, K. Kohara, and A. Terasaki, 2013, Eur. Phys. J. D 67, 80.

H2F+ : Herschel observation and laboratory chemical reaction study
K. Kawaguchi,
Department of Chemistry, Okayama University, Okayama, Japan
In 2013, the pure rotational lines JKaKc = 212 - 101 and 110 - 101 of H2F+ were searched
toward W31C, NGC 6334I, GC IRS21, 2Mass J1747 with the Heterodyne Instrument for the
Far-Infrared (HIFI) on board the Herschel Space Observatory [1]. The transition frequencies
have been measured in laboratory [2,3]. The proton affinity of HF is smaller than that of CO
or N2, so H2F+ is expected to be produced in diffuse cloud by proton transfer from H3+ to HF.
In the two sources W31C and NGC 6334I, HF and H2Cl+ have been detected, and other twosources are known to have abundant H3+. By data analysis, the abundance of H2F+ is found to
be less than 1/57 of H2Cl+ for NGC 6334I. Since the cosmic abundance of fluorine is one-halfof that of chlorine, the small abundance of H2F+ may be explained by difference in production
and/or destruction mechanism of both ions.
In laboratory, we investigated time-variation of the absorption intensities of H2F+ andH2Cl+ vibration-rotation lines in the 3 μm region to determine ion-electron recombination
reaction rate constants, which have important roles for ion abundances in low density
interstellar clouds. We used an optical parametric oscillator (OPO) laser with high resolution
for absorption measurements. We employed pulsed discharge and measured time profiles of
the absorption lines of H2F+ at ν = 3251.99 cm-1 (v3 = 1-0, JKaKc = 313 ← 414), and H2Cl+ atν = 2691.24 cm-1 (v3 = 1-0, JKaKc = 606 ← 505). Figure 1 shows an example of observed time
profiles.
Initially, assuming the same densities of electron and positive ion, we attempted
1/N(density) plot in the secondary reaction scheme, but it was not possible to fit well. On theother hand, the decay was explained well by an exponential function, so we assumed the
decay by the pseudo-first-order reaction between ion and electron. We used the Langmuirprobe method for determination of electron density and derive the recombination rate
constants, as follows, ke(H2F+) = 3.8 (1.6) ×10-8cm3s-1, and ke(H2Cl+) = 2.4(1.0) ×10-8cm3s-1.
We did not find major difference between the H2Cl+ and H2F+ ions for recombination rates.
Small abundance of H2F+ compared with H2Cl+
in interstellar space is thought to be due to theDischarge on
difference in the formation reaction.
In diffuse clouds, the presence of HCl+ isimportant for production of H2Cl+, where theion has been detected by Herschel. The ion can
produce H2Cl+ by a reaction with H2. On theother hand, HF is not ionized in interstellar
radiation field. F+ reaction with H2 produces
HF+ [4], but F+ is not abundant in diffuse
clouds.
[1] K. Kawaguchi, R. Fujimori, T. Amano, and F.
Matsushima, Herschel OT2 (2013).
Fig.1 Time profile of the H2F+ line for[2] R. Fujimori, K. Kawaguchi, and T. Amano,
ion-electron recombination study
ApJ. Letters 729, L2 (2011).
[3]T. Amano, F. Matsushima, T. Shiraishi, C.
Schnozuka, R. Fujimori, and K. Kawaguchi, J. Chem. Phys. 137, 134308 (2012).
[4] D. A. Neufeld, and M. G. Wolfire, ApJ, 706, 1594 (2009).

Laboratory Spectroscopy of 1,2,3-butatriene cation H2CCCCH2+
as a Candidate for a Diffuse Interstellar Band Carrier
M. Araki, S. Uchida, Y. Matsushita, and K. Tsukiyama
Department of Chemistry, Faculty of Science Division I, JapanThe diffuse interstellar bands (DIBs) were first discovered in the optical absorption spectra onstars in about 1920. Carbon chain molecules were suggested as candidates for DIB carriers in1977 by Douglas [1]. Although large number of carbon chain molecules have been tested
based on this suggestion, DIBs have not been identified yet. In this study, an emission
spectrometer with hollow-cathode glow discharge and extended negative glow discharge
systems produced a spectrum including the 4905 Å band from 2-butyne H3C−C≡C−CH3 as
the precursor. Photoelectron spectroscopy of H2CCCCH2 [2] indicated that the simple carbon
chain molecule H2CCCCH2+ (1,2,3-butatriene cation) produces a 2B3u–X2B2g electronictransition at 4905 Å. However, the 4905 Å band does not match the reported DIBs. If theassignment of the 4905 Å band to H2CCCCH2+ is true, it becomes doubtful as to whether
carbon chain molecules are carriers of DIBs.
We confirmed the assignment of the band by using chemical and physical investigations [3].
The chemical behavior of the band was tested using several kinds of precursors in the
discharge. Physical investigation by electrode switching indicated that the origin of the 4905
Å band has a positive charge. The accompanying bands at around 4905 Å were analyzed by
the double-minimum torsional potential mode as shown in Figure 1. All of the investigations
and the analysis gave the consistent results with the assignment. Therefore the observed 4905
Å band was surely assigned to H2CCCCH2+. This cation does not correspond to the currentlyknown DIBs, even though this is one of the basic unsaturated carbon chain molecules. A
question about carbon chain molecules as carriers of DIBs may be raised.

Figure 1: The observed vibronic bands of the 2B3u–X2B2g electronic transition of H2CCCCH2+ (left). The
vibrational structure and the obtained double-minimum torsional potential (right).

References
[1]
[2]
[3]

A.E. Douglas, 1977, Nat 269, 130.
F. Brogli, et al., 1974, Chem. Phys. 4, 107.
M. Araki, S. Uchida, Y. Matsushita, & K. Tsukiyama, 2014, Journal of Molecular Spectroscopy 297, 51.

Atomic-scale insights of the chemistry occurring in the interstellar medium. Clues fromquantum chemical methods
A. Rimola1
1

Departament de Química, Universitat Autònoma de Barcelona, Catalonia, Spain

The existence of cosmic molecules is of great relevance due to due their connection with thechemical evolution steps occurring in the universe [1,2]. A key role of this chemical evolution
is played by gas-grain processes, which involve in part the interaction of gaseous moleculeswith dust particles and the subsequent chemical reactivity. The current knowledge of thesegas-grain processes is mostly based on spectroscopic observations, helped by laboratory
experiments and astrochemical models. This combination has been fruitful to determine some
important phsyico-chemical properties, such as the chemical activity of the gas-graininteractions [3,4]. However, this approach cannot provide atomic-scale information such as
the precise mechanistic steps of the reactions or the exact role played by the grains, a serious
limitation to fully understand the basic physical and chemical steps that lead to the chemicalcomplexity in space. This information gap can be filled in by using theoretical calculations
based on quantum mechanical approaches [5]. In this talk, examples on how these theoretical
calculations can contribute to interstellar-related chemical studies from providing an atomistic
interpretation of the gas-grain processes will be presented. In particular, results obtained fromsimulations devoted to the formation of H2 through H recombination on bare olivine surfaces(Figure 1a) [6] and to the formation of interstellar H2CO and CH3OH through H additions to
CO on water ice particles (Figure 1b) [7] will be shown. Results will provide both structuraldetails of the systems involved and energetic data of the reactions, which in turn can be used
as input parameters in astrochemical modelling studies. Estimates of tunneling contributions
by calculating both tunneling crossover temperatures and transmission coefficients will also
be presented.

Figure 1: Transition state of (a) H2 formation from H recombination on a Mg-rich olivine surface modeland (b) HCO formation from H addition to CO on a water ice particle model.

References[1]
A.G.G.M. Tielens, 2013, Rev. Mod. Phys. 85, 1021.
[2]
P. Caselli, & C. Ceccarelli, 2012, A&AR 20, 1.
[3]
L. Colangeli, T. Henning, J.R. Brucato, et al. 2003, A&AR 11, 97.
[4]
T. Hama & N. Watanabe, 2013, Chem. Rev. 113, 8783.
[5]
S.T. Bromley, T.P.M. Goumans, E. Herbst, A.P. Jones & B. Slater, 2014, Phys. Chem. Chem. Phys. 16,
18623.
[6]
J. Navarro-Ruiz, M. Sodupe, P. Ugliengo & A. Rimola, 2014, Phys. Chem. Chem. Phys.16, 17447.
[7]
A. Rimola, V. Taquet, P. Ugliengo, N. Balucani & C. Ceccarelli, submitted to A&A.

Molecular collisions for astrophyics: Theory and experiments
Laurent Wiesenfeld1
1
Univ. Grenoble Alpes, IPAG, F-38000 Grenoble, France&
CNRS, IPAG, F-38000 Grenoble, France

In order to retrieve actual molecular abundances from astrophysical observations ofmolecular spectral lines, knowledge of the rotational levels excitation schemes is essential, inorder to go beyond the Local thermodynamical Equilibrium approximation. Actual excitation
results of a trade-off between photon excitation and collisional excitation by the main
constituents of the interstellar gas, molecular hydrogen, and, to a lesser extent, atomic
hydrogen and helium. These rates are almost always obtained from theoretical investigations,by computing classical or quantum dynamics of the interaction of molecules with thesecolliders.
Many types of molecules are observed and consequently, many collisions have been studied
recently, like hydrides [1], water and its isotopomers [2], organic molecules [3]. Also,
conditions for absorption against the cosmic background or masing have been examined.
In order to assess the quality of the computations, a systemic comparison with experiments isbeing undertaken. Observables are mainly integral or differential cross-sections [4], as well aspressure broadening cross sections [5].
All comparisons show an agreement between theory and experiments, thereby validating thequality of the Potential Energy Surfaces and the quantum scattering computations.
References[1] Mathieu Lanza, Yulia Kalugina, Laurent Wiesenfeld and François Lique, 2014 J. Chem. Phys., 140, 064316(2] A. Faure, L. Wiesenfeld, Y. Scribano and C. Ceccarelli,2012 Mon. Not. R. Astron. Soc. 420, 699–704.
[3] L. Wiesenfeld‹ and A. Faure, 2013, Mon. Not. R. Astron. Soc., 432, 2573-8.
[4] C.-H. Yang, G. Sarma, D. H. Parker, J. J. ter Meulen, and L. Wiesenfeld, 2011, J. Chem. Phys, 134, 204308.
[5] Brian Drouin and Laurent Wiesenfeld,2012, Phys. Rev A86, 022705.

Progress in Chemical Simulations with Gas and Surface Chemistry
E. Herbst1
1Department of Chemistry, University of Virginia, United States
Astrochemistry is undergoing a period of growth spurred on by a generation of new andmore powerful telescopes. Analysis of both current and future data requires, in my view,
better and more detailed chemical simulations for diverse sources in both our galaxy andothers. A few examples of the need for better simulations will be given. I will then talkabout our research program in developing improved gas-grain chemical simulations
The grain surface chemistry will be emphasized because this field of chemistry is stillmuch less certain than gas-phase chemistry for a variety of reasons. Following a historyof techniques used to mimic surface/ice chemistry in interstellar sources, I willconcentrate on the most detailed stochastic method used to date: the continuous-time
random-walk approach [1]. But not only must the chemistry be treated better, the physics
must also be improved, and I will discuss our preliminary efforts to develop models
including both gas-grain chemistry and 3D magnetohydrodynamics. Initial calculations
show that there is a severe problem in the treatment of molecular hydrogen in interstellar
ices. A possible resolution of this problem will be discussed [2]. Despite all of these
improvements, it may well be that chemical simulations will not be able to keep up withthe overwhelming number of data in the ALMA age, and I discuss several alternatives.

References[1]
Q. Chang, & E. Herbst, 2014, ApJ 787, 135.
[2]
U. Hincelin, Q. Chang, & E. Herbst, 2014, A&A, submitted.

Investigation of 13C isotopic fractionation of HC5N in TMC-1
K. Taniguchi,1, 2 S. Takano,2, 3 H. Ozeki,1 N. Sakai,4 S. Yamamoto,4F. Nakamura,3, 5 and Z45 group1

Department of Environmental Science, Faculty of Science, Toho University, Japan
2
Nobeyama Radio Observatory, NAOJ, Japan3
Department of Astronomical Science, School of Physical Science, The Graduate University
for Advanced Studies, Japan
4
Department of Physics, Faculty of Science, The University of Tokyo, Japan
5
Devision of Theoretical Astronomy, NAOJ, Japan
Around 180 molecules have been detected in the interstellar medium (ISM) or circumstellar
shells until now, and approximately 40 % of the molecules in space are classified into carbonchain molecules. Therefore, it is important for astrochemistry to study these molecules. The
formation mechanisms of some of the carbon-chain molecules, which are abundant in the ISM,
have been studied by observations of 13C isotopic fractionation of these molecules (N. Sakai
et al. summarized [1]), including HC3N [2], which is the shortest carbon-chain molecule of cyanopolyynes. This observation aims at clarifying the formation mechanism of HC5N, which isthe second shortest carbon chain of cyanopolyynes.
We used the 45m telescope of Nobeyama Radio Observatory, and conducted observation in2014 March and April. We used the Z45 receiver, which is the low noise receiver at 45 GHz
region, and analyzed by a smoothed bandpass calibration method [3]. The observed source wasthe cyanopolyyne peak in Taurus Molecular Cloud -1 (TMC-1) (R.A. = 4h 41m 42s.29, Decl. =25° 41’ 27”.0, J2000). Normal species and five 13C isotopologues of HC5N were measured
using the J = 16 – 15 rotational transition at 42 GHz
region. We got the spectra with the signal-to-noise
ratio between 12 and 14.5 (Fig.1).
There is no clear 13C isotopic fractionation among
the five 13C isotopologues of HC5N. From these observational results, we concluded that the growth ofthe carbon chain of HC3N, which was considered as
one of the most possible formation mechanisms of
HC5N, HC7N and so on, may not be an important
formation mechanism of HC5N, because 13C isotopic
fractionation of HC5N does not clearly reflect that of
HC3N. We think at the present stage that HC5N ispresumably formed by reaction with nitrogen atom
[4]
, not with CN radical as in the case of HC3N.
Therefore, cyanopolyynes are probably not mainly
produced by the sequential carbon-chain growth of
the shorter member.
References[1] N. Sakai et al., J. Phys. Chem. A, 117(39), 9831 (2013). [2]S. Takano et al., Astron. Astophys., 329, 1156 (1998). [3] H.
Yamaki et al., PASJ, 64, 118 (2012). [4] A. J. Markwick et al.,ApJ, 535, 256 (2000).

Figure 1: The spectra of five 13C
isotopologues of HC5N

DNC/HNC Ratio in the IRDC clump G34.43+00.24 MM3
T. Sakai,1 N. Sakai,2 K, Furuya,3 Y. Aikawa,4 T. Hirota,5,6
J. B. Foster,7 P. Sanhueza,5,8 J. M. Jackson,8 and S. Yamamoto2
1

Graduate School of Informatics and Engineering, The University of Electro-Communications,Japan
2
Department of Physics, Graduate School of Science, The University of Tokyo, Japan
3
Leiden Observatory, Netherlands
4
Department of Earth and Planetary Sciences, Kobe University, Japan
5
National Astronomical Observatory of Japan, Japan
6
Department of Astronomical Sciences, Graduate University for Advanced Studies, Japan
7
Department of Astronomy, Yale University, USA
8
Institute for Astrophysical Research, Boston University, USA

In cold molecular clouds, deuterium is known to be fractionated into molecules, except for
HD. The equilibrium deuterium fractionation ratios of molecules depend on temperature,
where lower temperature leads to higher deuterium fractionation ratios. Sakai et al. (2012)
observed the DNC/HNC ratio toward 16 clumps, including the infrared dark clouds (IRDCs)
and high-mass protostellar objects (HMPOs), by using the Nobeyama Radio Observatory 45
m telescope. Sakai et al. found that the DNC/HNC ratio of some IRDCs is lower than that of
the HMPOs, although the temperature of the IRDCs is lower than that of the HMPOs. In
order to investigate the origin of the low DNC/HNC ratio of the IRDCs, we have observed the
IRDC clump G34.43+00.24 MM3, which has the lowest DNC/HNC ratio in the sample ofSakai et al. (2012), in the DNC J=3-2 and HN13C J=3-2 lines with the Atacama Large
Millimeter/submillimeter Array. Then, we have found that the DNC emission is stronger
than the HN13C emission toward most parts of this clump. The DNC/HNC ratio averaged
within the 15"x15" area around the phase center is derived to be higher than 0.08. This ratio ismuch higher than that in the previous single-dish observation (~0.003). It seems likely thatthe DNC and HNC emission observed with the single-dish telescope traces lower density
envelopes, while that observed with ALMA traces higher density and highly deuterated
regions. We have compared the observational results with the model calculation results inorder to investigate the behavior of DNC and HNC in the dense cores. Taking these results
into account, we have reinterpreted the previous single-dish survey results.
References[1]

Sakai, T., Sakai, N., Furuya, K., Aikawa, Y., Hirota, T., Yamamoto, S. 2012, ApJ, 747, id. 140

Optically thick HI in the local interstellar medium: An alternative to “dark gas”
Y. Fukui,1
1

Department of physics, Nagoya University, Japany

Hydrogen is the main element in the Universe and it is of fundamental importance tounderstand the behavior of atomic and molecular hydrogen. The 21cm line of atomic
hydrogen is generally assumed to be optically thin in text books on astronomy. This implies
that the HI intensity is exactly proportional to the total HI gas column density. A comparison
between HI intensity and dust opacity obtained by Planck, however, shows a poor correlation
within 200 pc of the sun, which is inconsistent with optically thin HI if the dust properties are
uniform in the local space. We have found that the HI gas at the highest dust temperatureobeys the optically thin limit, whereas most of the HI gas at lower dust temperature shows
lower intensity than expected from the dust opacity, suggesting significantly high opticaldepth of the HI line. We present a new method to calculate HI spin temperature Ts and HI
opacity by coupling the two equations of radiation transfer and HI opacity based on the
Planck dust properties. The results show that 70% of the local HI gas has Ts=15 – 40 K and HI
optical depth of 0.5 – 2.0 for typical NHI column density around 1021 cm-2. Typical density of
the HI is then calculated to be ~100 cm-3, which lies between those of the classical HI and CO
gas. We argue that such cold dense HI gas is a possible alternative as the dark gas candidate
which has been often debated as CO-free H2 gas.

Distributions of molecules in the circumnuclear disk and surrounding starburst ring in
the Seyfert galaxy NGC 1068 observed with ALMA
S. Takano,1,2 T. Nakajima,3 K. Kohno,4,5 N. Harada,6 E. Herbst,7
Y. Tamura,4 T. Izumi,4 A. Taniguchi,4 and T. Tosaki8
1

Nobeyama Radio Observatory, National Astronomical Observatory of Japan, Japan
Department of Astronomical Science, The Graduate University for Advanced Studies(SOKENDAI), Japan
3
Solar-Terrestrial Environment Laboratory, Nagoya University, Japan
4
Institute of Astronomy, The University of Tokyo, Japan
5
Research Center for Early Universe, School of Science, The University of Tokyo, Japan
6
Max Planck Institute for Radio Astronomy, Germany
7
Department of Chemistry, University of Virginia, USA
8
Department of Geoscience, Joetsu University of Education, Japan2

We report distributions of several molecular transitions including shock and dust related
species (13CO J = 1-0, C18O J = 1-0, 13CN NJ = 1J-0J, CS J = 2-1, SO NJ = 23-12, HNCO JKa,Kc= 50,5-40,4, HC3N J = 11-10, 12-11, CH3OH JK = 2K-1K, and CH3CN JK = 6K-5K) in the nearby
Seyfert galaxy NGC 1068 observed with ALMA [1]. The central ~1 arcmin (~4.3 kpc) of thisgalaxy was observed in the 100 GHz region with an angular resolution of ~4" x 2" (290 pc x
140 pc) to study the effects of an active galactic nucleus and its surrounding starburst ring on
molecular abundances. We present images (e.g., Fig. 1) and report a classification ofmolecular distributions into three categories: (1) molecules concentrated in the circumnuclear
disk (CND), (2) molecules distributed both in the CND and the starburst ring (CS andCH3OH), and (3) molecules distributed mainly in the starburst ring (13CO and C18O). In the
starburst ring, the relative intensity of CH3OH at each clumpy region is not consistent withthose of 13CO, C18O, or CS. This is probably caused by the unique formation mechanisms of
CH3OH.

Figure 1: Images of integrated intensity of 13CO, C18O, CS, and CH3OH. The central position and the 13COJ = 3–2 intensity peak at the south-west position in the starburst ring [2] are indicated with white crosses.

References[1]

S. Takano et al., 2014, PASJ 66, 75.

[2]T. Nakajima et al., PASJ submitted.

Variations in the CO2/H2O ice abundance ratios in nearby galaxies
M. Yamagishi1, H. Kaneda1, S. Oyabu1, D. Ishihara1, T. Onaka2, T. Shimonishi3, K. Furuya4,
Y. Aikawa3, T. Suzuki5
1

2

Graduate school of science, Nagoya University, Japan
Graduate school of science, The University of Tokyo, Japan
3
Graduate school of science, Kobe University, Japan
4
Leiden Observatory, Leiden University, The Netherlands
5
SRON, The Netherlands

Absorption features due to interstellar ices are observed in near- and mid-infrared spectra.
Among various parameters about ices, we focus on a CO2/H2O ice abundance ratio which
effectively reflects the ice-forming interstellar environment. In past studies, CO2/H2O ratios
show large variations from object to object in our Galaxy. The cause of the variations is,however, still under debate. In this study, we examine variations in CO2/H2O ratios in nearby
galaxies based on the AKARI near-infrared (2.5-5.0 µm) spectra for 1031 regions in 158
galaxies. The CO2/H2O ratios in the galaxies are in a range of 0.05-0.30. In the dataset, wefind a positive correlation between the CO2/H2O ratios and the Brα/PAH 3.3 µm ratios which
depend on the massive star-forming activities. Furthermore, we find a positive correlation
between the CO2/H2O ratios and the specific star formation rates of the galaxies, which
depend on the evolutionally stage of the galaxies. These results suggest that CO2/H2O ratios
are high in active star-forming regions in young galaxies. It is possible that cosmic-ray
induced UV photons due to the massive star-forming activities contribute to the CO2
formation. Finally, effects of cosmic-ray on the CO2/H2O ratio are examined by using a gasgrain chemical model. We also show initial results of the model calculations.

Figure 1: CO2/H2O ice abundance ratios plotted against the Brα/PAH 3.3 µm ratios for all theregions where H2O and CO2 ices are detected. The dashed line represents the best-fit relationin M82.

Experiments for ionic cluster formation using an ion drift-tube with selected-ion
injection
Y. Nakai1, H. Hidaka2, N. Watanabe2 and T. M. Kojima3
1

2

RIKEN Nishina Center for Accelerator-Based Science, Japan
Institute of Low Temperature Science, Hokkaido University, Japan
3
Atomic Physics Laboratory, RIKEN, Japan

Ion-induced nucleation has been regarded as one of important processes for gas-phasenucleation. It is because a free-energy barrier on fine-particles growth decreases by attractive
polarization forces between ions and atoms/molecules, as shown in the liquid drop model.
Ionic cluster formation, particularly, is a key subject; it is an early stage of the ion-induced
nucleation and governs the reactions on the subsequent stages.
The ionic cluster formation has been widely studied from various views of points. However,in many of experimental researches, the formation processes were triggered in a reactant gas
including both parent molecules of core ions and ligand molecules using discharge, a pulsed
electron beam, radiation sources, and so on. In such a situation, various ionic species can beproduced with desired core ions. Therefore, initial ionic reactions were not well defined,
generally. For elimination of reactions by undesired ions, we developed an experimental
apparatus based on an ion drift-tube with selected-ion injection [1-4], where only specific ions
are injected to a reaction cell.
The ions are extracted from an ion source and mass-selected using a Q-pole mass analyzer.
Then, the ions are decelerated and injected into a gas filled in the drift tube. The ions are
drifted with an average velocity defined by the electric field and the number density of themolecules in the drift tube. They concurrently react with molecules and ionic clusters aregrown. Finally, produced ionic clusters are extracted from the drift tube. The masses of theextracted ionic clusters are analyzed with another Q-pole mass analyzer. Thus far, we have
performed experiments for hydration of protons and NO+ ions near room temperatures. In this
symposium, we will exhibit our experimental apparatus and some of results for reaction
equilibria of proton hydration.
References
[1]
[2]
[3]
[4]

H. Böhringer and F. Arnold, 1983, Int. J. Mass Spectrom. and Ion Phys. 49, 61.
T. M. Kojima et al., 1992, Z. Phys. D: At., Mol. Clusters 22, 645.
H. Tanuma et al., 2000, Rev. Sci. Instrum. 71, 2019.
Y. M. Ibrahim, et al, 2005, J. Am. Chem. Soc. 127, 7053.

Formation of H3O+ hydrate by NO+ injection into drift tube filled with H2O/buffer
gases: separation between the contributions of two formation pathways
by the drift time measurements
H. Hidaka,1 Y. Nakai,2 T. M. Kojima,3 and N. Watanabe1
1Institute of Low Temperature Science, Hokkaido University, Japan
2
Nishina Center for Accelerator-Based Science, RIKEN, Japan
3
Atomic Physics Laboratory, RIKEN, Japan

H3O+ hydrate, H3O+(H2O)n, is known to exist in the terrestrial ionosphere in quantities. As
one of the important formation-pathway, H3O+(H2O)n formation by the accompanying releaseof nitrous acid (HONO) from NO+(H2O)m which is formed by the successive hydration ofNO+:
NO+ + H2O + M → NO+(H2O) + M
NO+(H2O)m-1 + H2O + M → NO+(H2O)m + M+
NO (H2O)m + H2O → H3O+(H2O)m-1 + HONO (m=3,4),
has been often proposed and indeed studied in flow-tube experiments[1,2].
However, in those experiments, the parent NO+ ions were produced by conventional electron
impact method and thus contained the metastable NO+. Since the ionization energy to thelowest metastable state of NO+(a3∑+) is 15.66eV[3], H2O in the ground state having theionization energy of 12.65 eV can be ionized by the charge exchange with the metastable NO+
ions. If the charge-exchange reaction occurs, the new formation pathway of H3O+(H2O)n may
open as follows:
H2O + NO+( a3∑+)→ H2O+ + NO,
H2O+ + H2O → H3O+ + OH,+
H3O + H2O + M → H3O+(H2O) + M,
H3O+(H2O)n-1 + H2O + M → H3O+(H2O)n + M.
The above processes are not appropriate in atmospheric environments. Therefore, in order tostudy the formation pathway of H3O+(H2O)n via NO+(H2O)m alone, the formation of
H3O+(H2O)n through the charge-exchange reaction must be separated in the experiment.
Using a newly-developed ion drift-tube with selected-ion injection, we tried to separate thecontribution of metastable NO+ on the H3O+(H2O)n formation. In our experiment, the NO+
beam including the metastable NO+ was injected in the H2O/buffer gas filled drift-tube andthe products were mass-analyzed by the quadrupole mass spectrometer. Furthermore, the drift
time for the mass-selected H3O+(H2O)n was also measured, which provides the chemicalreaction history of products experienced. That is, when measuring the drift-time spectrum of
H3O+(H2O)n, the spectrum consists of two peaks depending on the different origins,
NO+(H2O)m or H2O+ from the metastable NO+. By varying the abundance of metastable NO+,the origins of two peaks were identified, respectively.

References
[1]
[2]
[3]

N. Eyet, et al., 2011, J. Phys. Chem. A 115, 7582.
F. C. Fehsenfeeld, M. Mosesman, & E. E. Ferguson, 1971, J. Chem. Phys. 55, 2120.
D. L. Albritton, A. L. Schmeltekkopf, & T. F. Morgan, 1979, J. Chem. Phys. 71, 3271.

On the Radiolysis of Ethylene Ices by Energetic Electrons and Implications
Li Zhou,1 Ralf I. Kaiser2
1

2

Chemistry Department, Nanchang University, Nanchang , China, 330031
Department of Chemistry, University of Hawaii, Honolulu, Hawaii, US, 96822

The investigation of the chemical evolution of the largest satellite of Saturn Titan
offers a unique opportunity to understand the origin and chemical evolution of the
Solar System especially of proto-Earth. In Titan’s atmosphere, nitrogen (N2, 98.4%)
and methane (CH4) are the dominating constituents with hydrocarbons such asacetylene (C2H2), ethylene (C2H4), diacetylene (C4H2), etc., several cyanides (HCN,HCCCN, C2N2), carbon dioxide (CO2), carbon monoxide (CO), and water (H2O)
being present in trace amounts. The gaseous molecules might also agglomerate toaerosol particles and sequester to Titan’s surface. In a pioneering study, Sagan andThomas outlined that energetic cosmic ray particles can penetrate deep into the lower
atmospheric layers. These energetic particles could incorporate part of their kinetic
energy into chemical reaction and thus process simple organics in Titan’s lower
atmosphere. In a more recent study, Molina-Cubero et al. derived an energy
deposition on Titan’s surface of 4.5×109 eVcm-2s-1. However, the radiation processingof these simple organics by energetic electrons is not well understood. To shed lighton this matter and to gain a comprehensive picture on the hydrocarbon chemistry, we
present data on the interaction of ionizing radiation, in form of energetic electrons,with solid ices of acetylene, ethylene, and ethane (C2-ices) at temperatures between
10 and 70 K. We will also investigate to what extent the radiation processing can leadto the formation of polymer-like macromolecules, which could present building
blocks of Titan’s organic aerosol layers, via heterogeneous chemistry.
L. Zhou, W. Zheng, R.I. Kaiser, A. Landera, A. M. Mebel, M. C. Liang, Y.L. Yung, Cosmic-Ray
Mediated Formation of Benzene on the Surface of Saturn’s Moon Titan. ApJ 718, 1243-1251(2010).
L. Zhou, S. Marry, M. Abplanalp, A.Turner, R.I. Kaiser, On the radiolysis of Ethylene ices byenergetic electrons and Implications to the Extraterrestrial Hydrocarbon Chemistry. ApJ 790, 38,
1-10 (2014).

Hydrogen atom desorption from water ice by 157 nm irradiation at 8-130 K
A. Yabushita1 and M. Yamazaki2
1

Department of Molecular and Material Sciences, Kyushu University, Japan2
Department of Molecular Engineering, Kyoto University, Japan

Interstellar grains typically consist of silicates or carbonaceous cores and are covered
predominantly by water ice. In a diffuse cloud, the ice mantle is subjected to vacuumultraviolet (VUV) irradiation [1]. Photodissociation of H2O molecules yielding H + OH
fragments is the major channel in the gas phase photolysis for 105–185 nm. The excessenergy over and above that required to break the HO–H bond appears predominantly as
product translation:(1)
H2O(ads) + h  H* + OH, H = 5.6 eV
where H* represents a highly translationally excited H photoproduct with a few eV. Energetichydrogen atoms could drive chemical reactions that are endothermic, or possess activationenergy barriers.
In an ultrahigh vacuum chamber, amorphous solid water (ASW) and polycrystalline ice (PCI)
films were prepared on a cooled platinum substrate [2]. A water ice film was photodissociatedat 157 nm with a pulsed laser. Resonance-enhanced multiphoton ionization was used to probe
H atom photoflagments. Translational energy distributions of H atoms were obtained byanalyzing the time-of-flight (TOF) mass spectra of H atoms.
TOF spectra of H atoms from photodissociation of ASW and PCI ice films were measured at
8 K. Both of them could be characterized by a combination of three (fast(A, Ttrans = 4750 K),
medium(B, Ttrans = 625 K), and slow(C, Ttrans = 100 K) different Maxwell-Boltzmann energy
distributions. Each TOF spectrum consists of the same three components, but contributions ofeach component are different.
TOF spectra were measured in the range of 8-130
K. The average translational temperatures of thecomponent (A) and (B) didn’t change, but that of
the component C increased with substratetemperatures above 90 K. Integrated H signal
intensities of the component (A) and (B) were
nearly constant in the range of 8-70 K. Molecular
dynamics simulation shows the H atom
photodesorption probability in the top fourmonolayers does not depend on ice temperature at
10, 20, 30 and 90 K [3]. These results imply that
Fig. 1 Desorption mechanisms for hydrogenthe component (A), (B) and (C) come from the atoms from photodissosiation of water ice
topmost H2O layer, some layers just below the
topmost H2O layer and the deeper monolayers, respectively (Fig. 1).
References[1]
A. Yabushita, T. Hama, & M. Kawasaki, 2013, J. Photochem. Photobiol. C. 16, 46[2]
A. Yabushita, D. Kanda, N. Kawanaka, M. Kawasaki, M. N. R. Ashfold, 2010, J. Chem. Phys. 125,
133406[3]
C. Arasa, S. Andersson, H. M. Cuppen, E. F. van Dishoeck, & G.-J. Kroes, 2010, J. Chem. Phys. 132,
184510

Photo-induced synthesis of interstellar organic matter: Volatile compounds and textureof organic residues
S. Tachibana1, T. Hama2, Y. Endo1, L. Piani1, H. Yurimoto1 and A. Kouchi2
1Department of Natural History Sciences, Hokkaido University, Jaoan
2Low Temperature Institute, Hokkaido University, Japan

Various organic compounds, discovered in the interstellar medium, are the products of photoinduced low-temperature chemistry in dense clouds. These organic compounds are one of the
precursors of the solar system, and are preserved in solar-system small bodies (comets andasteroids). Investigation of extraterrestrial organic matter has shown that organic matter withenrichment of D and 15N could be originated in low-temperature environments, but it is notclear how low-temperature dense-cloud organic matter evolve in the early solar system before
incorporation into small bodies.
In order to simulate the photo-induced synthesis of interstellar organic matter and its
subsequent thermal evolution, a new experimental apparatus, PICACHU (Photochemistry inInterstellar Cloud for Astro-Chronicle in Hokkaido University), was developed. In thepresentation, we report (1) in-situ analyses of volatile species sublimated from UV-irradiatedice during with increasing temperature and (2) laser- and atomic-force microscopeobservation of microtexture of organic residues.

Figure 1: PICACHU, Photochemistry in Interstellar Cloud for Astro-Chronicle in Hokkaido University.

Reproductive experiment of organic formation by catalytic reactions in the solar nebula
Y. Kimura,1 N. Watanabe,1 A. Tsuchiyama, 2 H. Nagahara, 3 and A. Kouchi1
1

Institute of Low Temperature Science/Hokkaido University, Japan
Division of Earth and Planetary Sciences, Kyoto University, Japan3
Department of Earth and Planetary Science, The University of Tokyo, Japan2

At the transition phase from molecular cloud to the solar system, organic molecules on thesurface of cosmic dust particles experienced environmental changing in wide range, i.e.,
increasing temperature and pressure. Then, some molecules released from the surface of dust
and the others reacted to be more complex organic molecules by assistance of catalytic dust.
ALMA is able to detect distribution profiles of sublimated molecules into gas phase in both ofmolecular cloud and extrasolar nebula with high spatial resolution and high sensitivity.
Recent high-resolution proves are also able to analyze the fine composition of meteorite andstardust samples and finding many kinds of organic materials. These organics may
contributed to the primordial organic system of the Earth. Unfortunately, however, there is noreal evidence about the process of organic formation in a solid phase. Although someexperimental studies have been performed using dust analogues, the elementary steps inmolecular evolution in the environment from molecular clouds to nebulae are still uncertain.
Catalytic reactions such as the Fischer-Tropsch type and Haber-Bosch type reactions
produce organic molecules efficiently on the surface of dust including iron at temperature
above 573 K [1,2]. Recently, we developed a new experimental system to test the catalytic
chemical reactions in the early nebula environment [lower temperature (100-500 K) andpressure (10-3-100 Pa)] using a substrate of magnesium silicate or iron. Figure 1 shows a photoof the system, which has a temperature controllable substrate made of gold. Silicate or ironwith a thickness of submicron is deposited onto the substrate and used as a substrate for thecatalytic reaction experiment. Molecules on the substrate are detected by a Fourier-transform
infrared spectrometer (FT-IR). Released molecules into the gas phase detect by quadrupole
mass spectrometers (Q-MSs). Here, we will show the preliminary results of the project.

Figure 1: Photo of the newly developed system for catalytic reaction experiment. This system has
differential pumping system, a temperature-controlled substrate (26-800 K), FT-IR, two Q-MSs and gas
flow controller.

References[1][2]

H. G. M. Hill, & J. A. Nuth, 2003, Astrobiology 3, 291.
J. A. Nuth, N. M. Johnson, & S. Manning, 2008, ApJ 673 L225.

High precision measurement of isotopic composition of amino acids
by LC x GC/C/IRMS
Y. Takano, Y. Chikaraishi, and N. Ohkouchi
Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
Nitrogen isotopic composition of amino acids has been widely applied to biochemical andgeochemical studies in an attempt to trace nitrogen source and transformation processes. For
accurate isotope analysis of individual amino acids, we validated a preparative method
involving the isolation of underivatized amino acids by ion-pair chromatographic separation andconfirmed the consistency of nitrogen isotope composition. Ion-pair reversed-phase liquid
chromatography coupled with electrospray ionization mass spectrometry (LC/ESI-MS) and gas
chromatography/ combustion coupled with isotope ratio mass spectrometry (GC/C/IRMS) wereconducted for the purpose of separation of underivatized amino acids and nitrogen isotopic
analysis, respectively. Firstly, we confirmed the resolution of proteinogenic andnon-proteinogenic amino acids by the preparative ion-pair LC separation. Diagnostic productions determined by mass spectrometry can support the rapid identification of individual aminoacids in screening analyses. Secondly, we observed no dependency on nitrogen isotopic
composition for the injection amount of underivatized amino acids and even for different
chemical formula including neutral, acidic, sulfur-containing, heterocyclic, and aromatic species.
The present method and strategy of LC coupled with GC/C/IRMS (i.e., LC x GC/C/IRMS) areuseful for the high precision determination of the nitrogen isotopic composition of amino acids,
in conjunction with an appropriate pre-treatment of chromatographic procedures.
R

NH2

IRMS

LC

GC

(1D-separation)

(2D-separation)

COOH

Amino acidion sourcemagnet

A

A

B

C D …ion source
+" +"
+" +"
+" +"
+" +"
+ + +
+" +"
+" +"
+ + +
+"
+" +"
+" +"
+"
+" +"+" +"

B
C
D

furnacesm/z 28 29

N2

Preparative collection
on a arbitrary purpose

Compound-specific
15N/14N analysis+" +"ESI-MS
Identification and determination

High precision measurementof amino acids for 15N/14N

Figure 1: Scheme and developed system of liquid chromatography x gas chromatography/ combustion/
isotope ratio mass spectrometry (LC x GC/C/IRMS) for precise compound-specific isotope analysis (CSIA)
and enantiomer-specific isotope analysis (ESIA) of amino acids.

References[1] Takano et al., 2009. Anal. Chem., 81, 394-399.
[2] Chikaraishi et al., 2010. Earth, Life, and Isotopes (Kyoto Univ Press), 367-386.
[3] Takano et al., 2010. Rapid Comm. Mass Spectrometry 24, 2317-2323.

Formation of clathrate hydrate from amorphous ice during warming
R. Netsu, T. Ikeda-Fukazawa
Department of Applied Chemistry, Meiji University, Japan
Water molecules are condensed on dust grains in interstellar molecular clouds and protester
nebulae. The water exists as amorphous ice in the cold clouds and is transformed into various
structures depending on thermal conditions and compositions with various deposited
molecules. Blake et al. [1] proposed the presence of CO2 clathrate hydrate in cometary ice.
From the results using the transmission electron microscopy (TEM) and fourier transformed
infrared spectroscopy (FT-IR), they showed the phase transition of vapor deposited
amorphous ice including CO2 and CH3OH into type-II clathrate hydrate at around 120 K.
Clathrate hydrates are inclusion compounds consisting of water molecules and a variety ofguests molecules. Most clathrate hydrates form one of two distinct crystallographic structures,type-I and –II, depending on the sizes and shapes of the guest molecules. The cubic unit cellof type-I clathrate hydrate contains 46 water molecules in a framework of two dodecahedraland six tetrakaidecahedral cages, and that of type-II clathrate hydrate contains 136 watermolecules in a framework of 16 dodecahedral and eight hexakaidecahedral cages. The
structure of CO2 clathrate hydrate formed under a high pressure condition is type-I [2]. For
the hydrate from the vapor deposited amorphous ice [1], the structure is type-II due to thehelp-gasses effect of CH3OH. For the CO2 clathrate hydrate grown epitaxially on a hydrate in
low pressure conditions, the structure depends on the structure of the hydrate as the substrate[3]. In order to investigate the formation mechanisms of pure CO2 clathrate hydrate in low
pressure conditions, we analyzed infrared spectra of vapor deposited amorphous ice including
CO2 during the warming.
The gas mixtures of H2O and CO2 with 1:1 in H2O:CO2 were deposited with 10±8 μm/min
onto a substrate of oxygen-free copper at 43 K. After the deposition, the substrate was
warmed from 43 to 160 K with a rate of 1-4 K/min. During the warming, the infrared spectra
were measured at intervals of 2 K using Shimadzu IRPrestige-21.
The results show that the spectral features change during the warming. From the analysis of
the wave numbers of the O‒H stretching modes of H2O and the C‒O asymmetric stretchingmodes of CO2, significant changes were found at around 100 K. The wave numbers of theO‒H stretching modes increase as the temperature increases at temperatures above 100 K,
whereas those decrease in lower temperatures. The wave numbers of the C‒O asymmetricstretching modes change significantly at around the temperature, and become almost
constants at temperatures above 100 K. Furthermore, a remarkable gas release and exothermic
temperature rise were also observed. The results suggest the crystallization of amorphous ice
at around 100 K. The spectral feature of the C‒O asymmetric stretching modes (i.e., the wave
numbers, widths, and intensity ratio of two peaks) indicates that the crystal is the type-I
clathrate hydrate. From the extrapolating the equilibrium line of the phase diagram of the
H2O-CO2 system to our thermal condition, we propose the formation of CO2 clathrate hydrate
from the vapor deposited amorphous ice in vacuo.
References
[1]
[2]
[3]

D. Blake, L. Allamandola, S. Sandford, D. Hudgins, & F. Freund, 1991, Science 254, 548 .
T. Ikeda, S. Mae, O. Yamamuro, T. Matsuo, S. Ikeda, & R. M. Ibberson, 2000, JPC A 104, 10623 .
F. Fleyfel, & J. P. Devlin, 1991, JPC 95, 3811 .

Crystallization mechanism of silicate formed from supersaturated vapor
investigated by in-situ IR measurement
S. Ishizuka1, 2, Y. Kimura2
1

2

Department of Earth Science, Tohoku University, Japan
Institute of Low Temperature Science, Hokkaido University, Japan

We have developed a new experimental apparatus, named Free-flying In-situ infraredmeasurement of Nucleating nanoparticle Experimental (FINE) system, by which we canmonitor dust imitated nanoparticles forming via homogeneous nucleation from
evaporated vapor [1]. In the present study, we monitored crystallinity of Mg-bearing
silicate (forsterite) formed from hot mixed vapor of Mg, SiO and O2.
As shown in Figure 1, we found that just nucleated nanoparticles have less crystallized
structure and crystallization proceeding as particles cool. Interestingly, crystallization
occurred in a gas atmosphere at ~500 K, which is significantly lower than previously
known crystallization temperature at 1000 K for amorphous silicate [2]. We concluded
that, in our experiment, crystallization proceeded from supercooled nano “droplets”, inwhich activation energy for crystallization is effectively reduced compared with that forcrystallization from amorphous. Here we report the brand new crystallization
mechanism and possibility that crystalline silicate formed from supercooled nano“droplets” in astronomical environment.
Figure 1: IR spectra measured at different
height from evaporation source at 2300±100 K.
Focusing on silicate 10 m band, just nucleatednanoparticles show broad feature attributable toless crystallized magnesiosilica and, in contrast,
cooled nanoparticles show sharp crystalline
feature. Crystallization effectively proceeded in
6-10 cm region where is estimated to be cooler
than 500 K [3].

References[1] S. Ishizuka, Y. Kimura & I. Sakon, 2014, ApJ, submitted[2] Koike, C., et al. 2010, ApJ, 709, 983[3] C. Kaito, 1991, Kemuri no Himitsu (only in Japanese), Kyouritsu Shuppan.

Hydrogen atom addition reactions to solid benzene by quantum tunnellingand its strong structure dependence
Tetsuya Hama,1 Hirokazu Ueta,1 Akira Kouchi,1 Naoki Watanabe,1 and Hiroto Tachikawa2
1

Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan
2
Division of Materials Chemistry, Hokkaido University, Sapporo, Japan

Aromatic and aliphatic hydrocarbons are abundant in the interstellar medium, and they carry anumber of infrared features. Benzene (C6H6), the simplest aromatic hydrocarbon, has been
detected in circumstellar environments such as post-asymptotic giant branch objects. Recent
experimental studies reported that aromatic hydrocarbons such as C6H6 and naphthalene(C10H8) are efficiently produced in cold interstellar clouds via gas-phase reactions [1]. One
might expect that the formation of saturated hydrocarbon can be easily achieved in theseregions considering the overabundance of hydrogen in the interstellar medium. However, an
activation barrier of about 20 kJ mol-1 generally exists for hydrogenation of aromatichydrocarbon in order to break the aromaticity. At typical interstellar grain temperatures, i.e.,
at T~10–50 K, C6H6 weakly adsorbs on the surface of interstellar dust grain through van der
Waals forces, which should only acts as an inert surface. Therefore, Hydrogen (H) atoms
cannot add to the C6H6 by overcoming the activation barrier.
The present study shows that H atoms canefficiently add to C6H6 molecules on the surfaceof amorphous C6H6 at 10–50 K by quantum
tunneling to form the cyclic saturated hydrocarbon,
cyclohexane (C6H12).
C6H6 + H → C6H7,
C6H7 + H → C6H8,
C6H8 + H → C6H9,
C6H9 + H → C6H10,
C6H10 + H → C6H11,
C6H11 + H → C6H12,

Ea = 15.5 kJ mol−1,
Ea = 6.3 kJ mol−1,
Ea = 10.5 kJ mol−1,

(1)
(2)
(3)
(4)
(5)
(6)

Here, Ea represents the activation barrier in thegas phase. The radical–radical recombination
reactions (2), (4), and (6) should be barrier-less.
We also report that the surface structure strongly
determinedthehydrogenation
efficiency;hydrogenation was completely suppressed on a
crystalline C6H6 surface.

References[1]

Jones et al., 2010, PNAS 108, 452.

Fig.1 Infrared absorption spectra over therange of 3200–800 cm−1 for (upper panel)
amorphous solid C6H6 and (lower panel) the
crystalline C6H6 of 6 × 1015 molecules cm−2
at 20 K: (a) before and (b) after cold H atom
exposure for 180 min. (c) differential
spectra upon H atom exposure on the two
surfaces ((b) − (a)).

H-D Substitution Reactions of Solid Ethanol with Atomic Deuterium
via Quantum Tunneling at Low Temperatures
K. Osaka,1 Y. Oba,1 A. Kouchi,1 and N. Watanabe1
1Institute of Low Temperature Science, Hokkaido University, Japan

It has been recently revealed that surface reactions on interstellar dust play an important rolein enrichment of deuterated species observed in molecular clouds as compared with thecosmic D/H ratio. Previous experimental studies demonstrated that molecules such asformaldehyde, methanol, and methylamine can be deuterated by surface reactions with
deuterium (D) atoms at very low temperatures [1-3]. This process most likely consists of theradical formation through H abstraction by D atoms (e.g., CH3OH + D → CH2OH + HD) andthe following D addition to the radical to form deuterated isotopologues (e.g., CH2OH + D →CDH2OH). In molecular clouds, there are certainly more complex organic molecules than
CH3OH. For example, ethanol (CH3CH2OH) has been observed toward Sgr B2(ethanol/methanol ~ 0.02 – 0.2) [4]. The correlation between such complex organic molecules
and their reactivities with D atoms is still not experimentally investigated.
Here, we studied H-D substitution reactions of CH3CH2OH solid, which has more substituent
groups than CH3OH. The obtained results were compared with a previous theoretical study.
The present study provides important insights into reactivity of other astronomical moleculeswith D atoms. Experiments were performed using the Apparatus for SUrface Reations in
Astrophysics (ASURA), which mainly consists of a main chamber, and an atomic sourcechamber. Pure solid CH3CH2OH (10 K) was exposed to cold D atoms (100 K). Subsequently
the change in the composition of ethanol was measured using FT-IR in situ.
H-D substitution occurred in the ethyl group but were negligible in the hydroxyl group, whichis consistent with the methanol case [2]. We also found that the D-H substitution reaction on
CD3CD2OD also occur when solid CD3CD2OD was exposed to H atoms at 10 K. We willfurther discuss the temperature dependence of each reaction at 10-30 K and the difference ofreactivity for each functional group.

References[1] N. Watanabe & A. Kouchi,, 2008, Prog. Surf. Sci. 83, 439[2] A. Nagaoka, N. Watanabe, & Akira Kouchi, 2007, J. Phys. Chem. A 111, 3016
[3] Y. Oba, et al., 2014, Meteoritics & Planetary Science 49, 117[4] M. Ikeda, et al., 2001, ApJ 560, 792

Hydrogen addition reactions of simple aliphatic hydrocarbons (C2H2 and C2H4)~ clue to the formation mechanism of cometary C2H6~
H. Kobayashi,1 N. Watanabe,2 H. Hidaka,2 T. Hama,2 Y. Watanabe,1and H. Kawakita1
1

Koyama Astronomical Observatory, Kyoto Sangyo University, Japan
2
Institute of Low temperature Science, Hokkaido University, Japan

Comets are thought as remnants of planetesimals formed in the early solar nebula. Their
nuclei consist of volatile ices and dust grains that were formed in the pre-solar molecular
cloud and probably chemically altered in the proto-planetary disk. Although the outline ofevolution from a molecular cloud to the disk is basically understood, detailed chemical
processes are still in debate. To investigate the links between proto-planetary disk and themolecular cloud, we focused on cometary ethane (C2H6) which is considered to form throughthe hydrogen addition reactions on the cold grain surfaces. C2H6 and accetylene (C2H2), theparent molecule of the C2H6, have been observed in multiple comets since 1996 and theirabundances relative to water (the major component of cometary ices) is ~0.001 with somevariations [1]. Such variation might be caused by the difference in the mixing ratios between
the materials originated in the molecular cloud and the disk-processed materials. C2H6 has
never been detected in molecular cloud thus we evaluate experimentally the hydrogenation
processes to form the C2H6 from C2H2 (C2H2 -> C2H3 -> C2H4 -> C2H5 -> C2H6). In theprevious experimental studies [2], it was concluded that the reaction from C2H4 to C2H6 isconsiderably rapid than the reactions from C2H2 to C2H4 and it would be a reason for theabsence of C2H4 in comets. To investigate those reactions quantitatively in realistic
conditions of molecular clouds, we performed the laboratory measurements of hydrogen
addition reactions of C2H2 and C2H4 on amorphous solid water.
The experiments were conducted by using laboratory setup for surface reaction in interstellar
environment (LASSIE) at Institute of Low Temperature Science, Hokkaido University [3].
Atomic hydrogen used for the reactions were produced by the dissociation of hydrogenmolecules in micro-wave induced plasma. The kinetic temperature of hydrogen atoms were~120K and the H-atom flux was ~1013 cm-2s-1. The samples of pure solid C2H2, C2H4 andthose on ASW were produced on the substrate located in the center of the main chamber at
10K and 20K. Infrared absorption spectra of the ices were measured by FTIR before andduring the exposure of H-atom.
Although our measurements show basically the same trend as shown in the previous studies,
the difference in reaction rates for C2H2 and C2H4 was found to be much less than that
previously reported. We will discuss the temperature and thickness dependence of the time
constant for the sample ices in the poster.
References
[1]
[2]
[3]

M. J. Mumma & S. B. Charnley, 2011, Annu. Rev. Astro, Astrophys. 49, 471.
K. Hiraoka, T. Takayama, A. Euchi, H. Handa, & T. Sato, 2000, ApJ, 532, 1029
N. Watanabe & A. Kouchi. 2002. ApJ, 571, L173

Nitrogen isotopic fractionation of ammonia by adsorption on grain surface:
An experimental approach to understand 15N-enriched organic mattersin extraterrestrial materials
H. Sugahara, Y. Takano, N. O. Ogawa, Y. Chikaraishi, and N. Ohkouchi
Department of Biogeochemistry, Japan Agency for Marine-Earth Science and Technology(JAMSTEC), JAPAN
Nitrogen isotopic composition of the solar system objects show a variation in the range of minus
hundreds to plus thousands permil in δ15N value (‰, normalized as vs. Air). The bulk δ15N valuesof the solar system, which are inferred from the analysis of the solar wind samples returned byGenesis mission, exhibit around −400‰ and those of the protosolar nebula are considered assimilar values [1]. The bulk δ15N values of Jupiter atmosphere are also similar to those of the solar
wind [2]. Conversely, the terrestrial planets (Venus, Earth, and Mars) show much more positive
values ranging from −40 to +350‰ [3, 4]. Primitive solar system materials, such as chondrites,
comets, and interplanetary dust particles (IDPs) also show various degrees of 15N-enrichment up to+1500‰ in the bulk δ15N value [5, 6]. Furthermore, anomalously high 15N-enrichments, as called
hot spots, are frequently found within a single material and their highest δ15N values reach as highas +5000‰ [7]. However, only a few models can explain the considerable δ15N diversity in theinterstellar medium (ISM) [e.g., 8] and likely isotopic discrimination processes have never been
well understood.
In the study, we shed light on an adsorption of ammonia on grain surface as a potential mechanism
for 15N-discrimination in ISM. Adsorption is an interaction between gaseous molecules and grainsurface and may be a first step for grain surface chemistry to form more complicated organic
matter. We focused on ammonia in this study, because it is one of major carrier forms of nitrogenin ISM and also a high-active chemical as a precursor for nitrogen-involving organic matters. As apotential model for the 15N-discrimination through adsorption process on grain surface, we
enclosed ammonia gas into vacuumed glass vials together with several absorbent materials. We
determined the difference in δ15N value between the initial ammonia gas and the absorbed one.
References[1] B. Marty, M. Chaussidon, R.C. Wiens, A.J.G. Jurewicz, & D.S. Burnett, 2011, Science 332, 1533 .
[2] M.M. Abbas, A. LeClair, T. Owen, B.J. Conrath, F.M. Flasar, V.G. Kunde, C.A. Nixon, R.K. Achterberg, G. Bjoraker,
D.J. Jennings, G. Orton, & P.N. Romani, 2004, APJ 602, 1063 .
[3] J.H. Hoffman, R.R. Hodges, M.B. McElroy, T.M. Donahue, & M. Kolpin, 1979, Science 205, 49 .
[4] K.J. Mathew & K. Marti, 2001, JGR 106, 1401 .
[5] L. Bonal, G.R. Huss, A.N. Krot, K. Nagashima, H.A. Ishii, & J.P. Bradley, 2010, GCA 74, 6590 .
[6] J. Manfroid, E. Jehin, D. Hutsemékers, A. Cochran, J.-M. Zucconi, C. Arpigny, R. Schulz, J.A. Stüwe, & I. Ilyin, 2009,
A&A 503, 613 .
[7] G. Briani, M. Gounelle, Y. Marrocchi, S. Mostefaoui, H. Leroux, E. Quirico, & A. Meibom, 2009, PNAS 106, 105222 .
[8] S.D. Rodgers & S.B. Charnley, 2008, Mon.Not.R.Astron.Soc.385, L48 .

Infrared characteristics of carbonaceous materials irradiated by nitrogen plasma
K. Sato,1 I. Sakon,1 T. Onaka,1 T. I. Mori,1 M. Hammonds,1 S. Kimura,2 and S. Wada
1

2

Department of Astronomy, Graduate School of Science, the University of Tokyo, JapanThe Center for Instrumental Analysis, The University of Electro-Communications, Japan

Recent observations have discovered buckminsterfullerene (C60) in planetary nebulae (PNe)[1][2]. In addition to the emission from C60, the spectra also show broad emission plateau in
the 6-9 micron region in three PNe [3]. This feature is thought to be carried by mixtures ofaromatic/aliphatic hydrocarbons [2][3]. However, we have limited knowledge on the chemicaland evolutionary relation among C60 and other carbonaceous dust such as polycyclic aromatichydrocarbons and hydrogenated amorphous carbons, which has to be examined based on notjust observational studies but also laboratory experiments.
We have performed the experiments to investigate the infrared characteristics of thelaboratory-synthesized materials after irradiating nitrogen plasma to C60 as an initial step.
This experiment aims to investigate the infrared characteristics of nitrogen-bearing
carbonaceous materials.
Figure 1 shows the infrared absorption spectra of the synthesized materials in our experimentswith different irradiation time. Each spectrum shows a feature at about 6.3 micron and anotherfeature whose peak position varies from 8.1 to 8.3 micron depending on the irradiation time.
Features peaking at those wavelengths can be contributed by aromatic and aliphatic C-C andC-N bonds [4][5]. In this presentation, we discuss the effect of nitrogen/carbon ratio andaliphatic/aromatic bond ratio on the infrared spectra of the nitrogen-bearing carbonaceous
materials synthesized in our experiments.
3

4 min
6 min
8 min

Absorbance (arbitrary units)

2.5
2
1.5
1
0.5
0
-0.5
4

5

6

7
8
9
Wavelength (um)

10

11

12

Figure 1: The infrared absorption spectra of the materials synthesized with different irradiation time. The
continuum is subtracted. The small bump at 9 micron is an artifact due to the spectral structure of a silicon
substrate.

References
[1]
[2]
[3]
[4]
[5]

J. Cami, J. Bernard-Salas, E. Peeters, & S. E. Malek, 2010, Science, 329, 1180.
D. A. García-Hernández, A. Manchado, P. García-Lario, et al., 2010, ApJ, 724, L39.
J. Bernard-Salas, J. Cami, E. Peeters, et al., 2012, ApJ, 757, 41.
L. J. Allamandola, A. G. G. M. Tielens, & J. R. Barker, 1989, ApJS, 71, 733.
“The Sadtler Handbook of Infrared Spectra”, Sadtler Research Laboratories, 1978.

Detectability of Prolate Symmetric-Top Molecules in Diffuse Clouds
by a “Hot-Axis Effect”
M. Araki,1 S. Takano,2 N. Kuze,3 T. Oyama,1 K. Tsukiyama1
1

2Faculty of Science Division I, Tokyo University of Science, Japan
Nobeyama Radio Observatory and the Graduate University for Advanced Studies (Sokendai),Japan
3
Faculty of Science and Technology, Sophia University, JapanThe aim of this study is to detect prolate symmetric-top molecules in diffuse clouds byobservations of absorption lines by a “hot-axis effect.” Molecules in low excitation
temperatures in diffuse clouds can be detected by only absorption. A prolate symmetric-top
molecule, such as CH3CN and CH3CCH, has a special advantage to detect absorption lines.
The K rotation (rotation around the red dotted lines in Figure 1) is excited by collisions in ahigh kinetic (collisional) temperate and is not cooled by radiation. On the other hand, the J
rotation is cooled well by radiation due to a permanent dipole moment and the low radiative
temperature as shown in Figure 1. As a result, the special advantage is that the J = K
rotational levels have population concentrations as shown in Figure 2. We call the population
concentrations a “hot-axis effect.” Absorption lines of the J + 1 ← J (= K) and ΔK = 0
transitions indicated by the red arrows in Figure 2 can be strong. To calculate the population
concentrations, both of radiation and collisions should be considered simultaneously. In thecase of a linear molecule the equation for rotational distribution by radiation and collisions
was derived by Oka et al. [1]. Recently Araki et al. derived the equation in the case of asymmetric-top molecule having the hot-axis effect [2]. Using the equation the population
concentrations of CH3CN and CH3CCH were calculated and the intensities of absorption lines
were estimated. Therefore it is suggested that the absorption lines enhanced by the hot-axis
effect can be the powerful probe of the molecules in diffuse clouds.

Figure 1: Hot-axis effect for a prolate symmetric
top molecule. The red dotted line is the hot axis.

References[1][2]

Oka et al., 2013, ApJ, 773, 42.
Araki et al., 2014, AJ, in press.

Figure 2: Population concentrations at the J = K
levels for a prolate symmetric top molecule. The
emissions are drawn by the black arrows. The J =K levels are descried by the blue bars and thestrong absorptions are by the red arrows.

Laser Spectroscopic Study of CaH in the UV region
K. Watanabe, K. Kobayashi, F. Matsushima, and Y. Moriwaki
Department of physics, University of Toyama, Japan

Intensity /arb. units

The electronic transitions of CaH were found in the Sun and M dwarfs [1, 2]. The
transitions of CaH in the stellar atmospheres changes depending on the gas pressure, therefore
CaH bands can be used to determine luminosity and surface gravity of cool stars [3-5].
Spectroscopic studies on CaH began in the 1920’s [6], and many studies have been carried out
since then. Bernath’s group observed transitions of CaH in the IR and visible regions andidentified A2, B2+, E2 states [7-10]. Bell et al. extensively assigned D 2+-X 2+ bands in
the UV region [11]. In their study, the change in the previous vibrational assignments of theD 2+ state was suggested and interactions between B 2+, C 2+, and D 2+ were discussed to
explain the irregular vibrational spacing of the D 2+ state. The ab initio calculations haveshown that B 2+ and D 2+ of CaH has complex potential curves [12, 13]. Due to the avoided
crossing, it is suggested that the B 2+ has an interesting double minimum potential. We havecarried out a laser induced fluorescence (LIF) study of transitions in this UV region (360 430 nm). We have produced CaH by the laser ablation of a calcium target in the hydrogengas environment.
The several bands of D 2+-X 2+ of CaH was observed and CaH production was
confirmed. In addition, extra bands were observed. Figure 1 shows the part of the spectra
showing one of the extra band. By using the combination differences of CaH, the lower state
was confirmed to be the vibrational ground state of X 2+state. We will discuss the upper
state of this band.

25400

25500

25600

25700

References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]

25800

Laser Wavenumber /cm-1
Figure 1: Part of the CaH spectra identified in this work.

C. M. Olmsted, Astrophys. J. 27, 66(1908).
A. Eagle, Astrophys. J. 30, 231(1909).
J. R. Mould, Astrophys. J. 207, 535(1976).
J. R. Mould et al. ,Mon. Not. Roy. Astron. Soc. 181, 625(1977).
B. Barbuy et al. , Astron. Astrophys. Suppl. 101, 409(1993).
R. S. Mulliken, Phys. Rev. 25, 509(1925).
A. Shayesteh et al. ,J. Mol. Struct. 695-696, 23(2004).
R. S. Ram et al. , J. ,Mol. Spectrosc. 266, 86(2011).
Gang Li et al. , J. Quant. Spectrosc. Rad. Transfer, 113, 67(2012).
A. Shayesteh, et al. J. Mol. Struct. 288, 46(2013).
G. D. Bell et al. Physica Scripta, 20, 609(1979).
P. F. Weck and P. C. Stabcil, J. Chem. Phys. 118, 9997(2003).
H. Martin, J. Chem. Phys. 88, 1797(1988).

25900

～

High Resolution Spectroscopy of the 2A2 – X 2B1 Electronic Transition of Phenoxy Radical asa Candidate of Diffuse Interstellar Bands Carrier
Y. MATSUSHITA, M. ARAKI, K. NIWAYAMA and K. TSUKIYAMA
Faculty of Science Division I, Tokyo University of Science, Japan
Diffuse Interstellar Bands (DIBs) still haven’t been identified, although several hundreds ofbands have been detected [1]. To identify DIBs, we observed the laboratory absorption spectra～of the 2A2 – X 2B1 electronic transition of the phenoxy radical C6H5O by cavity ring down
spectroscopy. The radical was produced by pulsed discharge with a hollow cathode (inside
diameter: 2 cm) using a gas mixture of anisole C6H5OCH3 (0.1 Torr) and herium (0.4 Torr) ina cell. The optical cavity in the cell was formed with two high-reflectivity mirrors (R >99.99 %). Laser pulses transmiting the cavity were detected with a photomultiplier tube andring down curves were acquired with an oscilloscope. The three absorption bands having thelarge intervals about 500 cm-1 were measured in the 5700－6200 Å region and were assigned～
to the 2A2 – X 2B1 electronic transition as shown in Figure 1 because the origin band of theelectronic transition was reported at around 6200 Å in matrix [2] and the measured threebands were assigned to the 1-0, 2-0, and 3-0 bands of the ν11 mode by comparing with the

1-0



3-0

2-0

11

16200 16400 16600 16800 17000 17200 17400

2-0

Intensity (arb. units)

Intensity (arb. units)

frequencies obtained by a quantum chemical calculation (B3LYP/cc-pVTZ). The three bands
include the two shoulder peaks at the lower-wavenumber side as shown in Figure 2. The
shoulder peaks can not be assigned to the hot bands of the ν11 mode due to the large intervals
from the main band (ν11 = 2-0). The relative intensity of the shoulder peaks were tested in a
dry-ice temperature. Decreasing of the relative intensity suggested that the peaks are
attributed to the hot bands of the lowest vibrational mode (ν20).

16600

16700

-1

16800

16900

17000

-1

Wavenumber (cm )Wavenumber (cm )Figure 1: Absorption spectra of the phenoxy radical

Figure 2: The 2-0 band and the shoulder peaks～of the 2A2 – X 2B1 electronic transition of theReferences[1] Heger M. L., Lick Obs. Bull. 10, 141 (1922)[2] Radziszewski et al., J. Chem. Phys. 115, 9733 (2001)

phenoxy radical

Stabiliity of Glyciine and Interstellar C
Carbonaceous Dust An
nalogs undeer UV Irradiationand Elecctron Bombbardment
B Maté, I. Tanarro,
B.
T
M.. A. Morenoo, M. Jimén
nez-Redondoo,
V. J. Herrero, V
V. Timón an
nd R. Escrib
bano1
1

Insstituto de Esstructura dee la Materiaa IEM-CSIC
C, Serrano 123,
1 28006 Madrid , Sppain

The forrmation andd survival of moleculles in extraaterrestrial environmennts is a su
ubject ofconsiderable intereest. For exam
mple, the sttability of organicomoleecules undeer the high radiationr
flux andd low temperature connditions fouund at the su
urfaces of manymsolar system objects is a
key queestion in asttrobiology. Even harshher conditions exist in thet interstelllar mediumm (ISM).
Dust graains in the ISM
I
are frequently sim
mulated by meansmof hyydrogenatedd amorphou
us carbon(HAC) pparticles geenerated in thet lab [1].
o glycine [2], we pressent here ou
ur investigaation on the stability
Further to our prevvious work onof glyciine and HA
AC particles under irraddiation withh UV photoons (~165 nnm) and witth 2 keVelectronns, aiming tot simulate the effectss of cosmicc rays preseent in diffeerent region
ns of theinterstelllar medium
m. The evolu
ution of the samples is monitored with infrareed spectrosccopy.
In addittion, we disscuss theoreetical calcullations that add some light to the adsorptionn processof glyciine at the suurface of carrbonaceous materials.
-1--12136 cm
COC

2110 cm
CxOy-12164 cmc
OCN-

Figure 1:: IR spectra ofo amorphous glycine depoosited at 25 K.
K Top: 600 nm deposit beefore (black) anda after(red) 5 hoours processiing by UV phhotons. Bottom
m: 900 nm saample, beforee (black) and after (red) 5 hours
bombarddment with 2.0 keV electro
ons. Right pannel: detail and assignmentts of C-O streetching regionn.

Referen
nces
[1]
[2]

Y.. J. Pendleton & L. J. Allammandola, Ap. JJ. Supp. Ser. 2002,
2
138:75.
B.. Maté et al., 2011,2
Phys. Chhem. Chem. P
Phys. 13, 1226
68.

Infrared activation of the breathing mode of methane
R. Escribano, O. Gálvez, V.J. Herrero, B. Maté, V. Timón, M.A. Moreno
Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, 28006 Madrid, Spain

The breathing mode of methane, an in-phase stretching and shrinking of all four C-H bonds
where the C atom and the charge distribution remain undisturbed, is inactive in the infrared
spectrum of gas-phase or of pure solid methane. However, in low-temperature methane/water
mixtures, like those generated to model astrophysical ices, a small but distinguishable feature
has been observed in IR spectra, at the expected frequency of this vibration. Hodyss et al. [1]were the first to report this observation, which was subsequently confirmed by Gálvez et al.
[2]. Although weak in general terms, the strength of this anomalous band could be large
enough to allow detection in astrophysical or atmospheric field observations, thus providing a
direct evidence of the presence of a form of methane in direct interaction with water.
We have built theoretical models that mimic experimental samples of CH4/H2O mixtures in an
attempt to understand this effect, and to find out if, and when, this activation is predicted. Our
results for a number of quantum chemical models turn out to be diverse, ranging from noactivation at all to the prediction of some very strong features in specific cases.
For our calculations we have used several modules of the Materials Studio package, namely
Amorphous Cell, Adsorption Locator, and CASTEP, which allow building models foramorphous solids for specific values of density and temperature and predicting theirvibrational spectra. We have considered two amorphous water (ASW) models, of densities 0.7
g cm-3, to simulate low-density ASW, and of 0.94 g cm-3, for more compact water solids.
Methane molecules were added to these amorphous structures at 30 K, in CH4/H2O ratios
varying between 1/20 and 1/8.

Figure 1: IR spectra of a 1:3 CH4:H2O mixture deposited at 14 K (black, above), and of pure CH4 (blue,
below). Inset: enlargement of the breathing mode region; the band is forbidden for pure CH4, but it
becomes as strong as a the ν2+ν4 combination band for the mixture.

References[1][2]

R. Hodyss et al. “Photochemistry of methane-water ices”, 2008, Icarus, 200, 338.
O. Gálvez et al. “Spectroscopic effects in CH4/H2O ices”, 2009, Ap. J. 703:2101

Structures of surface and grain boundary of amorphous ice
Y. Kumagai and T. Ikeda-Fukazawa
Department of Applied Chemistry, Meiji University, Japan
In interstellar molecule clouds, the elements such as hydrogen, oxygen, carbon, and nitrogen,deposit on dust grains, and amorphous H2O ice and various molecules (e.g., CO, CO2, NH3,
CH4, H2CO, and so on) are formed [1]. Because the molecules undergo chemical evolutions
through various processes on the surface of amorphous ice, the structure and properties ofamorphous ice surface is one of the important factors govern the chemical evolutions oforganic molecules in molecular clouds.
For crystal ice, the quasi-liquid layer exists on its surface [2]. The dangling motion of the freeO˗H bond which exists at the surface causes the surface melting [3]. The impurities adsorbedon the surface have effects to promote the dangling motion [4]. Although there are various
studies on structure and properties of ice crystal, the surface properties of amorphous ice areless understand because of its complicated structure. In order to investigate the structures of
surface and grain boundary of amorphous ice, we performed molecular dynamics (MD)calculations of amorphous ice.
The MD calculations were performed using an atom-atom potential model, KKY potential
model with the program MXDORTO [5]. Using a system consisting of 2760 water molecules,
an infinite surface was simulated by replicating the cell in the directions parallel to the surface
using periodic boundary conditions. The amorphous structure with 1.03 g cm˗3 in density was
prepared by quenching of a liquid water phase from 290 to 10 K. For the simulations of thesintering process, two amorphous ice layers with about 40 Å in thickness were arranged with
10-20 Å in intervals.
The results show that the surface layer with low density exists in amorphous ice. The surface
layer has high amplitude of thermal vibration of water molecules in comparison with bulk
state, because the water molecules in the layer form a few of hydrogen bonds with weakerstrength. Furthermore, the sintering processes were calculated to investigate the structure ofgrain boundary formed from adsorption of two surfaces. In the case that the initial interval of
the two layers is 10 Å, the layers gradually move and are sintered within 100 ps. The sintering
is not observed in the cases that the intervals of the layers are greater than 15 Å for our
simulated time scale (~180 ps). The density of the boundary between the layers increases
during the sintering, and becomes a constant at around 100 ps. The reached density wasslightly lower than the value of bulk. The present results suggest the existence of theboundary with low density between amorphous ice grains. The structures of surface andinterface might have important implications for adsorption, diffusion, and chemical reaction
in interstellar amorphous ice.
References
[1]
[2]
[3]
[4]
[5]

A. Kouchi, T. Yamamoto, T. Kuroda, & J.M. Greenberg, 1994, A. & A. 290, 1009.
M. Faraday, 1859, Philos. Mag. 17, 162.
T. Ikeda-Fukazawa & K. Kawamura, 2004, J. Chem. Phys. 120, 1395.
T. Ikeda-Fukazawa & K. Kawamura, 2006, Chem. Phys. Lett. 417, 561.
K. Kawamura, MXDORTO, Japan Chemistry Program Exchange, No.029.

A Theoretical Study of H2 Adsorption on Ice XI Surfaces
Y. Kunisada, and N. Sakaguchi
Center for Advanced Research of Energy and Materials,
Faculty of Engineering, Hokkaido University, Japan
In the evolution of molecules in space, it is assumed that physicochemical processes mainly
proceed on cosmic dust grains.[1] Because of low temperature character of interstellar
medium in space, only exothermic reactions can proceed in the gas phase. On the other hand,in the case of surface reactions in dense clouds, heat of formation can be effectively released
to surfaces. Thus, various kinds of reactions can occur on surfaces. Therefore, in order tounderstand evolution of molecules in space, it is important to know the environmental
temperature, i.e. gas and surface temperature, at the time of physicochemical processes.
One of the ways to investigate the environmental temperature at the time of physicochemical
processes is a measurement of nuclear spin temperature of H2 in space. Since protons are
fermions, the total wave function of H2 must be anti-symmetric with respect to the exchangeof two nuclei. According to this anti-symmetry requirement for the total nuclear wave
function, H2 are classified as ortho and para species, i.e., ortho H2 and para H2 have total
nuclear spin I=1 and 0, respectively. In the case of isolated H2 molecule, ortho-para (o-p) H2
conversion occurs quite slowly because such nuclear spin conversion is strictly forbidden.
Corresponding o-p H2 conversion time is 2.0×1021 s.[2] Thus, nuclear spin temperature of H2
may conserve the environmental temperature at the time of H2 formation processes. But it has
been reported that o-p H2 conversion can be enhanced on ice surfaces.[3-5] Therefore, it isimportant for interpretation of nuclear spin temperature of H2 to reveal the accurate o-p H2
conversion rate. In order to investigate o-p H2 conversion rate, we have to clarify theinteraction between H2 and ice surfaces.
In this study, we investigated the adsorption properties of H2 on ice surfaces with the aid of
the first principles calculations based on density functional theory. We focused on the H2adsorption on ice XI surfaces to consider the effect of ferroelectric properties of crystalline ice
surfaces. Moreover, we took the van der Waals interaction into consideration with the
non-local correlation functional vdW-DF [6] to treat H2 adsorption states on ice XI surfaces
accurately.
At first, we investigated the adsorption energy of H2 on ice XI surfaces. In this study, we
adopted the 2x1 ice XI surface super cell with 12x12x32 grids as adsorption configurations.
We calculated the adsorption energy at each grids point. We found that the hollow site is themost stable adsorption site. In the workshop, we will also show the quantum and isotope
effect on adsorption and diffusion properties.

References[1]
T. Hama, & N. Watanabe 2013, Chem. Rev. 113, 8783.
[2]
K. Pachucki, & J. Komasa, 2008, Phys. Rev. A 77, 030501(R).
[3]
N. Watanabe, Y. Kimura, A. Kouchi, T. Chigai, T. Hama, & V. Pirronello, 2010, ApJ, 714, L233.
[4]
T. Hama, K. Kuwahata, N. Watanabe, A. Kouchi, Y. Kimura, T. Chigai, & V. Pirronello, 2012, ApJ, 757,
185.
[5]
T. Sugimoto, & K. Fukutani, 2011, Nature Phys. 7, 307.
[6]
M. Dion, H. Rydberg, E. Schröder, D. C. Langreth, & B. I. Lundqvist, 2004, Phys. Rev. Lett. 92, 246401.

Solving the Schrödinger equations of interstellar molecules
H. Nakashima1 and H. Nakatsuji1
1

Quantum Chemistry Research Institute (QCRI), Japan

Schrödinger equation is the most fundamental equation in quantum mechanics and it governs
most of phenomena in molecular science including space chemistry of interstellar molecules.
In spite of that importance, however, the exact solutions of this equation have not been able tobe solved for over 80 years. Recently, Nakatsuji was successful to propose a new general
theory, the free complement (FC) method, for solving this equation [1] and theory was also
extended to solving the relativistic Dirac equation [2]. In the tests with a few electron systems,
the extremely accurate results could be obtained [3] and the stringent tests of the exactness ofthe obtained wave functions indicate how accurately the FC wave function can provide close
to the exact solutions [4]. With different from ordinary quantum chemistry, the FC method isbased on the idea that the exact wave function should be obtained by a functional of the
Hamiltonian. Therefore, the adequate wave functions are automatically generated by thesystem's Hamiltonian itself and this feature is significant for space chemistry that appears thevarious unusual situations and environments.
We have applied the present method to various atoms and molecules [5] and also interstellar
species with the environments of space. In the latter case, the following situations are rather
significant: the accurate excited states and theoretical spectra, non Born-Oppenheimer (nonBO) calculations which include the quantum effect of nuclear motion [6], solving therelativistic Dirac equation [2], and atoms and molecules in an extreme environment such as
under the strong magnetic fields [7]. For example, the non-BO calculations can provide thevibronic and rotational states including all the quantum effects of electron and nuclear motion,
whose theoretical results are directly comparable with the observations and/or experimental
results. For the last topic, the Universe's strongest magnetic field was observed on Magnetar
object surface in space and the quantum mechanical calculations in magnetic fields become
realistically important.
Thus, the present method indicated a high potentiality to be helpful for doing space chemistryin Schrödinger accuracy. We now continue to develop the methods and computationalalgorithms to be more easily applicable to more general atoms and molecules.
References
[1]
[2]
[3]
[4]
[5]

[6]

[7]

H. Nakatsuji, 2000, J. Chem. Phys. 113, 2949. H. Nakatsuji, 2004, Phys. Rev. Lett. 93, 030403. H.
Nakatsuji, 2005, Phys. Rev. A 72, 062110.
H. Nakatsuji & H. Nakashima, 2005, Phys. Rev. Lett. 95, 050407.
H. Nakashima & H. Nakatsuji, 2007, J. Chem. Phys. 127, 224104. Y. Kurokawa, H. Nakashima, & H.
Nakatsuji, 2008, Phys. Chem. Chem. Phys. 10, 4486.
H. Nakashima & H. Nakatsuji, Phys. Rev. Lett. 2008, 101, 240406.
H. Nakatsuji, H. Nakashima, Y. Kurokawa, & A. Ishikawa, 2007, Phys. Rev. Lett. 99, 240402. H.
Nakatsuji, 2012, Acc. Chem. Res. 45, 1480. H. Nakatsuji & H. Nakashima, 2014, TSUBAME e-Science J.
11, 24 (2014).
Y. Hijikata, H. Nakashima, & H. Nakatsuji, 2009, J. Chem. Phys. 130, 024102. H. Nakashima, Y.
Hijikata, & H. Nakatsuji, 2013, ApJ 770, 144. H. Nakashima & H. Nakatsuji, 2013, J. Chem. Phys. 139,074105.
H. Nakashima & H. Nakatsuji, 2010, ApJ 725, 528. A. Ishikawa, H. Nakashima, & H. Nakatsuji, 2012,
Chem. Phys. 401, 62.

Collision dynamics of PAH clusters with charged particles
M. Nakamura1 and A. Ichimura2
1

College of Science and Technology, Nihon University, Japan
2
Institute of Space and Astronautical Science, JAXA, Japan

The polycyclic aromatic hydrocarbon (PAH) molecules are believed to be abundant ininterstellar space. The collisions dynamics of charged particles with PAH clusters would play
an important role in the chemical evolution in molecular clouds. Recently, there have been
experimental studies for the collision of ions with PAH molecules and PAH clusters [1,2]. In
the present work, we make an analysis for the experimental observation. In the collision withsingly and doubly charged 3He ions, doubly charged clusters of anthracene and coronene weredetected for cluster size n ≥ 15. To analyze the origin of this appearance size, we propose astacked structure model [3]. In the model, it is assumed that a PAH cluster takes a layer
structure of planar molecules. (See Fig. 1) The appearance sizes are calculated for doubly
charged clusters of benzene, anthracene and coronene by the present model [3] and by theconventional liquid drop model [4]. They are shown in Table 1 together with experimental
results [1-2,5]. For benzene cluster, the liquid drop model gives a considerably good
agreement with the experiment [5] while the stacked structure model does not at all. For
anthracene and coronene clusters, both models conspicuously underestimate the appearance
sizes in comparison with the experimental results [1-2]. The origin of this discrepancy is
discussed. The result was partly reported in [3].

Fig. 1: Stacked structure model for stability for fragmentation of doubly charged PAH cluster.
Table 1. Appearance sizes of doubly charged clusters.
constituent

experiment

benzeneanthracene
coronene

23
15
15

stackedstructure
model
9
6
3

liquid drop
model
18
6
3

References[1] A. I. S. Holm et al., Phys. Rev. Lett. 105, 213401 (2010) ; P. Rousseau et al., Nucl. Instr. Phys. Res. B 279,
140 (2012)[2] H. A. B. Johansson et al., Phys. Rev. A 84, 043201 (2011)[3] M. Nakamura and A. Ichimura, Physica Scripta T 156, 014063（2013）[4] O. Ehct et al., Phys. Rev. A 38, 3236 (1988)[5] M. Y. Hahn et al., J. Chem. Phys. 88, 4242 (1988)

Chemical Reactions in Protoplanetary Disks and Possibility of Detecting H2O Snowline
using Spectroscopic Observations
S. Notsu,1 H. Nomura,2 and D. Ishimoto1,2
1Department of Astronomy, Graduate School of Science, Kyoto University, Japan
2Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Japan

In the hot inner part of protoplanetary disks, H2O evaporates from the dust surface into gas.
On the other hand, it freezes on the dust surface in the cold outer part of the disks. H2O
snowline is the line which divides the two different regions [1]. H2O ice enhances the solidmaterial in the cold outer part of a protoplanetary disk, which promotes the formation of coresof gaseous planets. We can also regard H2O snowline as the dividing line between formating
regions of rocky planets and gas giant planets. In the case of disks around solar-mass T-tauristars. it is considered that the H2O snowline exists at a few AU from the central star.
Therefore, it is difficult to detect H2O snowline of exoplanetary systems by imaging
observations, since their spacial resolution is insufficient.
In contrast, H2O emissions from protoplanetary disks are detected by recent observations of
Spitzer and Herschel telescope. Zhang et al. (2013) [2] estimated the position of H2O
snowline by using the intensity ratio of different H2O lines, but the result depends on themodel of temperature distribution in the protoplanetary disk. In this work we propose themethod of detecting H2O snowline more directly by analyzing the velocity profiles of H2Oline spectra which will be obtained by high dispersion spectroscopic observations in near
future.
First, we calculate chemical reactions using a self-consistent physical model of protoplanetarydisks and investigate abundance distribution of H2O gas and the position of H2O snowline.
As a result we confirmed that the abundance of H2O is high not only in the inner region of
H2O snowline near the equatorial plane but also in the hot surface layer of outer disk.
Second, we calculate the velocity profiles of H2O emission lines from protoplanetary disk,
and found that we can obtain the information of H2O snowline through investigating the
profiles of some emission lines which have small Einstein A coefficient and large excitationenergy. The wavelengths of the useful H2O emission lines range from mid-infrared tosubmillimeter. We also discuss the possibility of future observations.

References
[1]
[2]
[3]

C. Hayashi,1981, Progress of Theoretical Physics Supple-ment 70, 35
K. Zhang, K. M. Pontoppidan, C. Salyk, et al. 2013,ApJ 766, 82
C. Walsh, T.J. Millar, & H. Nomura, 2010, ApJ 722, 1607

Chemistry in protoplanetary disks with the effects of the grain growth
D. Ishimoto,1,2 H. Nomura,2 C. Walsh,3 and T. J. Millar4
12Department of Astronomy /Kyoto University, Japan
Department of Earth and Planetary Science, Institution/Tokyo Institute of Technology, Japan
3
Leiden Observatory /Leiden University, Netherlands
4
School of Mathmatics and Physics /Queen’s University Belfast, UK

Planetesimals are thought to be formed in protoplanetary disks as a result of grain growth, butmany uncertainties are still remained in this process. So observations of disks in transientperiod which has large grain are good for understanding planetesimal formation.
Observational instruments are developed recently like ALMA, and theoretical study of thesedisks become important.
In this study, we calculate the chemistry and radiative transfer to investigate the influences of
the grain growth on chemical structure of protoplanetary disks. In the case of large grains,
FUV radiation can penetrate near the midplane because of the low opacity, and that changes
the gas temperature. As a result, most molecules are abundant near the midplane comparedwith the case of small grains.
The results of calculations of radiative transfer are shown in Figure 1. Line of CO3-2 is
optically thick even in the case of small grain, so in the case of large grains, intensity of CO32 line is not much different from the case of small grain. On the other hand, intensity of CN32 line change greatly with the case of small grains and large grains. Line of CN3-2 is opticallythin in the case of small grain, but CN are abundant in the high density region(midplane) in
the case of large grains, so CN3-2 line is changed to optically thick.

Figure 1: Specific intencity as a function of radius; red line indicates the case of small grain, and green line
indicates large grain; (Left): CO 3-2, (Right): CN 3-2

Time and Space Variation of the Organic Particles in the Proto-Solar Disk
M. Numata,1 and H. Nagahara1
1

Department of Earth and Planetary Science, The University of Tokyo, Japan

It is one of the critical problems of planetary science whether organic materials formed in molecular
cloud were the origin of the organic materials of the planets and small objects. Nakano et al. (2003)
suggested that organic materials in meteorite parent bodies were not derived from molecular clouds,
because the compositional variation of the C and N contents of heated organic analogs does not agreewith that of carbonaceous chondrites. On the other hand, organic grains must have experienced
temperatures change according to the radial transport in the protoplanetary disk, which would havebeen resulted in compositional change and mixing of various organics in the protoplanetary disk.
In this study, we investigate the temporal and spatial change of distribution and chemicalcomposition of organic particles in the proto-solar disk by taking the experimental results by Nakano
et al. (2003) into consideration. We calculate the viscous disk evolution of the model by Ciesla(2010a) and location of individual particles position simultaneously. The temperature that eachparticle experienced is estimated on the basis of radial temperature distribution and the chemicalcomposition of individual particles is obtained by applying the results of heating experiments on
analog organic materials by Nakano et al. (2003).
The temporal change of organic particle distribution is shown in Fig. 1, which shows that particles
initially located in the outer region drift inward with logarithmic decay, and that organic particles
were stably present in the inner region after 106 year. Figure2 shows the C contents of the particles
corresponding to Figure1, where the vertical value of ~40 wt% represents the initial value at themolecular cloud. The composition of organics changes with time and space, and the total amount of
C decreases with distance. On the other hand, due to the radial transport, the inner region tends to beoccupied with primitive organics with time. Planetesimals formed at 2-3 AU at the early stage ofthe disk evolution would have contained organics that were thermally processed to various degrees,
whereas, those formed at the later stage would have contained organics that retained primitive
chemical composition originated from the molecular cloud.

Figure 1: Time-space variation of organic matterr
distribution

Figure 2: Time-space variation of composition oforganic material

References
F. Ciesla, 2010a, Icarus 208, 455; F. Ciesla, 2010b, ApJ 723, 514; F. Ciesla, 2011, ApJ 740, 1; Nakano et al., 2003 ApJ
592, 1252

Chemistry in a Forming Protoplanetary Disk
Yuri Aikawa1, Haruaki Yoneda1, Kenji Furuya,2 and Yusuke Tsukamoto3
1

Department of Earth and Planetary Sciences, Kobe University, Japan
2
Leiden Observatory, Netherland (JSPS Fellow)
3
Department of Physics, Nagoya University, Japan

Sun-like stars are formed by the gravitational collapse of dense cloud cores. Due to the
angular momentum conservation, circumstellar disks are naturally formed, which will be abirth place of planetary systems. While various molecules, including organics, are detected inpresetellar and protostellar cores, how they are incorporated to disks and then to planetarysystems remains an open question. In this presentation, we report results of our chemical
models starting from prestellar cores to protoplanetary disks. Using the 3D radiationhydrodynamics model of Tsukamoto et al (2013), we investigate if and how the molecules in
the cloud core are chemically modified in the process of disk formation.

References[1]

Tsukamoto, Y. and Machida, M. N. 2013, MNRAS 428, 1321

A Multi-Transition Study of Molecules toward NGC 1068
based on High-Resolution Imaging Observations with ALMA
T. Nakajima,1 S. Takano,2,3 K. Kohno,4,5 N. Harada,6 E. Herbst,7
Y. Tamura,4 T. Izumi,4 A. Taniguchi,4 and T. Tosaki8
1

Solar-Terrestrial Environment Laboratory, Nagoya University, Japan
Nobeyama Radio Observatory, National Astronomical Observatory of Japan, Japan3
Department of Astronomical Science, The Graduate University for Advanced Studies(SOKENDAI), Japan
4
Institute of Astronomy, The University of Tokyo, Japan
5
Research Center for Early Universe, School of Science, The University of Tokyo, Japan
6
Max Planck Institute for Radio Astronomy, Germany
7
Department of Chemistry, University of Virginia, USA
8
Department of Geoscience, Joetsu University of Education, Japan2

We present 0.8-mm band molecular images and spectra obtained with the Atacama Large
Millimeter/submillimeter Array (ALMA) toward one of the nearest galaxies with an active
galactic nucleus (AGN), NGC 1068. Distributions of CO isotopic species (13CO and C18O)
J=3-2, CN N=3-2 and CS J=7-6 are observed toward the circumnuclear disk (CND) and a partof the starburst ring with an angular resolution of ~1.3"×1.2". The physical properties of thesemolecules and shock-related molecules such as HNCO, CH3CN, SO, and CH3OH detected inthe 3-mm band [1] were estimated using rotation diagrams under the assumption of LTE [2].
The rotational temperatures of the CO isotopic species and the shock-related molecules in the
CND are, respectively, 14-22 K and upper limits of 20-40 K. Although the column densitiesof the CO isotopic species in the CND are only from one-fifth to one-third of that in the
starburst ring, those of the shock-related molecules are enhanced by a factor of 3-10 in the
CND. We also discuss the chemistry of each species, and compare the fractional abundancesin the CND and starburst ring with those of Galactic sources such as cold cores, hot cores, andshocked clouds in order to study the overall characteristics.

Figure 1: The top spectra (a) and (b) are at the central continuum position (in the CND), and the bottom
spectra (c) and (d) are at the position of the 13CO J=3-2 intensity peak in the starburst ring

References[1][2]

S. Takano, et al., PASJ, 66, 75 (2014)
T. Nakajima, et al., submitted to PASJ.

Distribution of Molecules in Spiral Arm of M51
Yoshimasa Watanabe,1 Nami Sakai,1 Yuri Nishimura,1 Kazuo Sorai,2and Satoshi Yamamoto1
1

Depertment of Physics, The University of Tokyo, Japan2
Department of Physics, Hokkaido University, Japan

Recently, chemistry of external galaxies has attracted more attention of astronomers than before, because various
molecular species become readily detected in nearby galaxies owing to rapid increase of sensitivity inradioastronomical observations. In general, chemical compositions observed toward external galaxies are`average' chemical compositions of a number of giant molecular clouds (GMCs). The GMC-scale chemicalcompositions are mostly in chemical equilibrium, and mainly depend on structures and environmental conditionsof GMCs. Therefore, they cannot directly be discussed on the basis of astrochemical concepts established in
nearby molecular clouds in our Galaxy. If the physical meaning of the GMC-scale chemical compositions is
adequately established by observational and theoretical studies, we can make use of it as a new tracer to diagnose
external galaxies.
With this motivation, we have carried out the spectral line survey toward the spiral arm of M51 with the
IRAM 30 m telescope and detected 13 molecular species (Watanabe et al. 2014). The excitation temperaturesof the molecules are estimated to be less than 10 K toward P1. Therefore, most of detected molecules would
reside in a cold (~10 K) and widespread molecular gas, although a part of molecular emissions may also comefrom the hot molecular gas. Based on this spectral line survey, we conducted mapping observation of CH3OH,
CS, CN, HNCO, C18O and 13CO with the CARMA interferometer. These molecules are successfully imaged
with sufficient signal-to-noise ratios. Although the CO isotopologues traces spiral arm structure, we can see
significant difference of the other distributions from molecule to molecule. These differences would beoriginated from the environment around GMCs or the dynamics in the spiral arm such as cloud-cloud collisions.
References[1]
Watanabe, Y. et al. ApJ, 788, 4

The spatial distribution of shock/dust-related molecules in the nearby starburst galaxy
NGC 253 observed with ALMA!

T. Izumi,1 K. Kohno,1,2 Y. Tamura,1 A. Taniguchi,1 S. Takano,3,4
T. Nakajima,5 T. Tosaki6, N. Harada7, and E. Herbst8!

1Institute of Astronomy, The University of Tokyo, Japan
2Research Center for Early Universe, School of Science, The University of Tokyo, Japan
3Nobeyama Radio Observatory, National Astronomical Observatory of Japan, Japan
4Department of Astronomical Science, The Graduate University for Advanced Studies(SOKENDAI), Japan
5Solar-Terrestrial Environmental Laboratory, Nagoya University, Japan
6Department of Geoscience, Joetsu University of Education, Japan
7Max Planck Institute for Radio Astronomy, Germany
8Department of Chemistry, University of Virginia, USA!

We present spatial distributions of typical dense gas tracers (CS J=2-1, 7-6), shock/dust-related
molecules (HNCO JKa,Kc=50,5-40,4, CH3OH JK=2K-1K, and CH3CN JK=6K-5K) and 3 mm
continuum emission in the central kpc region of the nearby starburst galaxy NGC 253, obtainedwith Atacama Large Millimeter/submillimeter Array (ALMA) cycle 0 observations. The
achieved sensitivity was ~ 0.5 mJy per 30 pc beam, at a velocity resolution of 10 km s-1. We
found that CS emission is concentrated toward the very nuclear region, whereas CH3OH and
HNCO are more prominent in the “super bubble” (expanding bubble probably caused bysuper(hyper)novae) region [1] than in the nucleus. The existence of the expanding bubble is also
confirmed in the channel map and the position-velocity diagram of CS, i.e., dense gas is also
expanding. From our results, the abundances of CH3OH and HNCO would be enhanced in the
super bubble region likely due to shocks. In addition, we found shock/dust-related molecules are
faint at the peak position of the 3 mm continuum emission. The initially high dust temperature
would restrain the formation of these species there [2].
CS (2-1)

CH3OH (2K-1K)

100 pcFigure 1: Integrated intensity maps of CS (left) and CH3OH (right) in the central ~ 0.5 kpc × 1 kpc region of
NGC 253. The central cross and the white ellipse in both panels indicate the peak position of the 3 mm
continuum emission and the synthesized beams, respectively. In the right panel, the red ellipse indicates thelocation of the “super bubble” [1]. The CH3OH emission is more prominent at the rim of the bubble. The color
scales are in the unit of Jy beam-1 km s-1.

!

References[1][2]

K. Sakamoto, et al., 2006, ApJ, 636, 685
T. Nakajima, et al., 2014, submitted to PASJ

A Substellar-Mass Protostar and its Outflow of IRAS 15398-3359 revealed bySubarcsecond-Resolution Observations of H2CO and CCH
Y. Oya,1 N. Sakai,1 T. Sakai,2 Y. Watanabe,1 T. Hirota,3 J.E. Lindberg,4,5 S.E. Bisschop,4,5 J.K.
Jørgensen,4,5 E.F. van Dishoeck,6,7 and S. Yamamoto1
1

2

Department of Physics, The University of Tokyo, Japan
Department of Communication Engineering and Informatics, Graduate School of Informatics
and Engineering, The University of Electro-Communications, Japan
3
National Astronomical Observatory of Japan, Japan
4
Center for Star and Planet Formation, Natural History Museum of Denmark, University of
Copenhagen, Denmark
5
Niels Bohr Institute, University of Copenhagen, Denmark
6
Leiden Observatory, Leiden University, The Netherlands
7
Max-Planck-Institut f ¨ur Extraterrestrische Physik, Germany

Subarcsecond (0”.5) images of H2CO and CCH line emission have been obtained in the 0.8
mm band toward the low-mass protostar IRAS 15398-3359 in the Lupus 1 cloud as one of the
Cycle 0 projects of the Atacama Large Millimeter/Submillimeter Array (ALMA). We havedetected a compact component concentrated in the vicinity of the protostar and awell-collimated outflow cavity extending along the northeast-southwest axis.
The
inclination angle of the outflow is found to be about 20º, or almost edge-on, based on the
kinematic structure of the outflow cavity. This is in contrast to previous suggestions of amore pole-on geometry.
The centrally concentrated component is interpreted by use of amodel of the infalling rotating envelope with the estimated inclination angle, and the mass ofthe protostar is estimated to be less than 0.09 Msun. Higher spatial resolution data areneeded to infer the presence of a rotationally supported disk for this source, hinted at by aweak high-velocity H2CO emission associated with the protostar. Although IRAS
15398-3359 and L1527 are both the warm-carbon-chain chemistry sources, their physicalproperties in the vicinity of the protostar are found to be much different from each other.
Thus, Chemical variation of the protostellar envelope do not originate from the present
physical structure.

Abundance Anomaly of the 13C Isotopic Species of c-C3H2
K. Yoshida,1 T. Tokudome,1 N. Sakai,1 Y. Watanabe,1 S. Takano,2 B. Lefloch,3 and S.
Yamamoto1
1Department of Physics, The University of Tokyo, Japan

2Nobeyama Radio Observatory and the Graduate University for Advanced Studies(Sokendai), Japan
3Institut de Planétologie et d'Astrophysique de Grenoble, France
It has been reported that the 12C/13C ratios of several carbon-chain molecules in cold clouds
are significantly higher than the interstellar elemental 12C/13C ratio of 60-70 [1]. For
example, the [CCS]/[13CCS] ratio is reported to be 230±130 [2], and the [CCH]/[13CCH]
ratio is reported to be higher than 250 [3] in the cold starless core TMC-1 (Cyanopolyyne
Peak; CP). In addition, two or more 13C species of a single molecular species have different
abundances. For Instance, Takano et al. [4] found that the relative abundance ratio of
H13CCCN, HC13CCN, and HCC13CN is 1.0 : 1.0 : 1.4 in TMC-1 (CP).
We recently found the similar anomaly for c-C3H2 toward low-mass star-forming region
L1527. Many lines of c-C3H2 and its 13C species detected in the spectral line surveys with the
NRO 45 m and the IRAM 30 m telescopes enable us to derive the 12C/13C ratios for the two
13C species accurately.
For c-C3H2, attempting to fit these lines by one rotational temperature and one column
density was not successful. We found systematic residuals in the fit. Then, we employ the twocomponent model, assuming inner warm and outer cold regions. We calculated the 12C/13C
ratio and found a systematic difference of the anomaly between them; the anomaly is
mitigated in the inner region. This is the first indication of the variation of the 12C/13C ratio
along star formation. This result suggests that the anomaly can be used as a new diagnostic
tool for physical and chemical evolution of protostellar cores.

Figure 1: Spectral lines of c-C3H2 and its 13C species observed toward L1527.

References
[1]
[2]
[3]
[4]

Lucas, R. & Liszt, H. 1998, A&A, 337, 246.
Sakai, N. et al, 2007, ApJ, 663, 1174.
Sakai, N. et al. 2010, A&A, 512, A31.
Takano, S. et al. 1998, ApJ, 329, 1159.

Origin of Methanol in the Starless Core, Taurus Molecular Cloud-1
T. Soma, N. Sakai, Y. Watanabe and S. Yamamoto
Department of Physics, the University of Tokyo, Japan
Methanol (CH3OH) is one of fundamental saturated organic molecules, and is widely
detected in star forming regions [1]. It is generally thought that CH3OH is produced on dust
grains and is liberated into the gas phase by various star formation activities (e.g. protostellar
heating and outflow shocks). However, CH3OH is also moderately abundant in cold darkclouds, and its origin is still controversial [2]. Non-thermal evaporation processes should play
an important role.
To examine this we have conducted high spectral resolution observations of CH3OH
toward the cyanopolyyne peak of Taurus Molecular Cloud-1 (TMC-1 CP). The spectral lineof CH3OH toward TMC-1 CP is found to have a double-peaked profile separated by 0.4 km
s-1. Since the double-peaked profile is observed for the 13C species of CH3OH, it is not due tooptical depth and/or self-absorption effects. The spectral line profile of CH3OH is muchdifferent from those of C34S, C3S, and HC7N observed toward this source. Statisticalequilibrium calculations are carried out for the 10,0 −00,0 A+, 20,2 −10,1 A+ and 30,3 −20,2 A+ linesof CH3OH, and the H2 density of the emitting region for the blue-shifted and red-shiftedcomponents are derived to be (1.7 ± 0.2) × 104 cm−3 and (4.3 ± 0.4) × 104 cm−3, respectively.
Although these densities are similar to or slightly lower than those found for the othermolecules, CH3OH is distributed differently. This has been confirmed by mapping
observations of the CH3OH 20,2 − 10,1 A+ and the C34S J = 2 − 1 lines around TMC-1 CP.
Non-thermal desorption from dust grains seems to be responsible for the gas-phase
CH3OH. The grain-surface origin of CH3OH is further confirmed by the CH3OH/13CH3OH
ratio. As for the desorption mechanism, weak shocks caused by accreting diffuse gas to the
TMC-1 filament, photoevaporation caused by the cosmic-ray induced UV radiation, anddesorption of excess reaction energy in formation of CH3OH on dust grain are discussed.

References[1][2]

Herbst, E., & van Dishoeck, E. F. 2009, ARA&A, 47, 427
Takakuwa, S., Mikami, H., Saito, M. et al. 2000, ApJ, 542, 367

Effects of Line Overlap in statistical equilibrium calculations of OH 18cm lines
Y. Ebisawa,1 H. Inokuma,1 Y. Watanabe,1 N. Sakai,1 H. Maezawa,2 K. M. Menten,3 and S.
Yamamoto1
1Department of physics, University of Tokyo, Japan
2Department of physics, Osaka Prefecture University, Japan
3MPIfR, Germany
The 18 cm OH transition is the first spectral line of interstellar molecules detected in the radio
wavelength region. It is the fine structure transition between the Λ-type doubling levels in thelowest rotational state (J=3/2, Ω=3/2), and consists of four hyperfine components (1612, 1665,
1667, 1720 MHz). It is well known that the relative population of the hyperfine structure levels
can attain values that deviate from LTE values. In our observation toward eastward of Heiles
Cloud 2 (HCL2), we found a clear absorption feature of 1612 MHz component. In order tointerpret this, we conducted statistical equilibrium calculations. As a result, we found that
intensities of the four hyperfine components of OH are sensitive to the temperature (Fig.1 left).
Therefore, they can be used as a good thermometer for quiescent molecular clouds.
However, we recently observed 1720 MHz absorption feature in the northwest of Taurus
Molecular Cloud-1 (TMC-1) (Fig.1 right). In order to interpret this 1720 MHz absorption
feature, we again conducted statistical equilibrium calculations considering the effect of Line
Overlap. As a result, we found that thermal Line Overlap could cause 1720 MHz absorption
feature when the column density of OH is high, the temperature is high, the linewidth is narrow
and there is no velocity gradient in the cloud. We also found that the effect of Line Overlap isnegligible as long as the column density of OH is not so high. Therefore, we can safely use four
hyperfine components of OH as a thermometer if the column density of OH is not so high.

Figure 1: (left) Intensities of the four hyperfine components of OH as a function of temperature derived
from the statistical equilibrium calculation. 1612 MHz line appears in absorption when the temperature ishigher than 40 K. (right) Intensities of the 1612 MHz line and the 1720 MHz line observed in thenorthwest of TMC-1.The 1720 MHz line appears in absorption.

Spectral Line Survey toward Quienscent GMC in the LMC
Y. Nishimura,1 T. Shimonishi,2 Y. Watanabe,1 N. Sakai,1 Y. Aikawa,2 A. Kawamura,3 and S.
Yamamoto1
1

The University of Tokyo, Japan
2
Kobe University, Japan
3
National Astronomical Observatory of Japan

Spectral line survey observations of three giant molecular clouds in the Large Magellanic
Cloud (LMC) have been conducted in the 3 mm band with the Mopra 22 m telescope.
Spectral lines of fundamental species such as CN, CS, SO, HCN, HCO+, and HNC aredetected in addition to CO and 13CO. Although the observed sources show different
star-formation activities, chemical compositions averaged over a molecular-cloud scale (10pc) with our telescope beam are found to be similar to one another. The observed chemicalcompositions are almost free from star formation activities and their feedbacks.
Nitrogen-containing species are confirmed to be deficient in comparison with the Galactic
molecular clouds due to a lower elemental abundance of nitrogen in the LMC. In spite ofgeneral resemblance of chemical abundances among the three sources, it is found that the
CS/HCO+ and SO/HCO+ ratios are slightly higher in a quiescent molecular cloud. An originof this trend is discussed in relation to possible depletion of sulfur along molecular cloudformation.

Study of Formation Processes and Chemical Conditions of L1544 Pre-stellar Core
N. Tanekura,1 H. Maezawa,1 and Y. Aikawa2
1
2

Department of Physical Science, Osaka Prefecture University, Japan
Department of Earth and Planetary Sciences, Kobe University, Japan

Dark cloud cores are star-forming sites. L1544 located in the eastern area of Taurus
molecular complex is a well-known dense pre-stellar core accompanied by a 0.1pc-scalerotating and collapsing disk [1,2,3,4]. We have conducted observations of some molecularspecies such as SO, CS, CCS, HC3N, N2H+, NH3 and so on, toward the L1544 core with the
NRO 45-m telescope. N2H+, NH3 and SO increase at the late stages of chemical evolution ofmolecular clouds, whereas carbon chain molecules such as CCS and HC3N increase in theearly stages. We found that the distributions of SO and CCS show the anti-correlation, and the
SO decreases at the center of the disk due to the depletion onto dust grains. These results arewell consistent with the conventional time-dependent chemical models [2]. Additionally it
was found that the maximum peak of SO exists in 0.1 pc northeast of the disk where N2H+
and NH3 were not detected, and the line intensity of CCS was very faint (Fig.1). According toa time-dependent chemical model (density=2.0E+04 cm-3, Av=8 mag), the chemical
abundances observed in the SO-clump correspond to those of the molecular cloud in the earlystage of chemical evolution (a few ten thousand years).
The parent cloud of L1544 core has blue and red-shifted velocity components [4]. The
rotating/collapsing disk appears to be located along the interface region of the twocomponents. On the other hand, the SO-clump adjacent to the disk belongs only to theblue-shifted one. This suggests that the encounter of the two clouds possibly induced theformation of the L1544 pre-stellar core with rotating/collapsing disk, and that the SO-clump is
still a chemically and physically young clump left behind by the evolution and formation of
the L1544 pre-stellar core. These observed results will be presented in this symposium.

Figure 1: Integrated intensity map of SO (JN=32-21) and the spectral lines observed toward the SO clump.

References[1] Ohashi et al, ApJ, 518, L41 (1999). [2]Aikawa et al, ApJ, 620, 330 (2005). [3]Caselli et al, ApJ, 565, 331(2002). [4]Tafalla et al, ApJ, 504, 800 (1998).

Processing of ices in a massive star-forming region
T. Shimonishi,1 T. Onaka,2 T. Mori,2 M. Yamagishi,3 and AKARI/IRC team1

2

Graduate school of science, Kobe University, Japan
Graduate school of science, The University of Tokyo, Japan
3
Graduate school of science, Nagoya University, Japan

Infrared absorption spectroscopy toward dense molecular clouds suggests that the bulk ofheavy elements exist in the solid phase as ices and dust. Understanding the effect of starformation activities on properties of ices is one of the key issues for interstellar ice chemistry
since chemical reactions in the solid phase play an important role in the chemical evolution ofstar- and planet-forming regions.
This study aims to clarify the effect of star formation activities on the chemical evolutionof circumstellar and interstellar ices. For this purpose, spatial distribution of ices in a nearby
high-mass star-forming region, Cepheus A, is spectroscopically mapped using the Infrared
Camera (IRC) on board the AKARI satellite. This is the first spectroscopic mapping of
circumstellar ices in a continuous 2—5 micron wavelength region. As a result of observations,infrared absorption bands due to major ice species such as H2O, CO2 and CO, are detectedfrom various regions in Cepheus A (Figure 1). Based on the spectral fitting, column densitiesof each molecular species are derived to map the spatial distribution of ices. We find that icecolumn densities are centrally concentrated toward the high-mass protostellar object HW2
located in a central part of Cepheus A. This suggests that observed ices are located in theenvelope of HW2. We also find that the column density ratio of CO2/H2O ices does not varysignificantly within a 0.1 pc region around HW2, suggesting that the chemical compositionsof ices are less affected by protostellar radiation. In this poster, we discuss the effect ofradiation and jet from the protostellar object on the chemical and physical properties ofcircumstellar ices.
Background:
AKARI/IRC 4 µm

30” = 0.1 pc

Flux [mJy]

IRC Slit position

H2O ice

CO ice

CH3OH ice?
+ Organics?

CO2 iceWavelength [µm]

Figure 1: Examples of AKARI/IRC near-infrared spectra observed toward the Cepheus A region. The
positions of detected ice absorption features are labeled in the upper right panel. The observed slit positions
are shown by the blue rectangles in the central panel; the background is AKARI/IRC 4 micron image of
Cepheus A.

3.3 micron feature variations in AKARI data
M. Hammonds, T. Mori, F. Usui, and T. Onaka
Department of Astronomy, University of Tokyo, Japan
Archived data from AKARI were analysed in the 2.5–5 µm region were analysed toinvestigate variations in the 3.3 µm PAH feature and related hydrocarbon emission bands.
PAHs (and/or related carbonaceous molecular species) comprise a substantial fraction of the
carbon budget in the Universe, making the study of their formation and evolution an
important means of understanding the behaviour and lifecycle of carbon in our galaxy andbeyond.
The data were investigated in the context of the interpretation that the 3.3 µm feature can be
decomposed into two closely spaced sub-features at 3.28 µm and 3.30 µm[1,2], in order toexplain the observed asymmetry and profile variation of the overall emission band. Ourfindings indicate that this feature is universally well described by these two components indata recorded using AKARI grism spectroscopy. The cause for these components is discussed
in terms of the structure of the emitting molecular carriers, and their relative abundance indifferent astrophysical environments. Further, a correlation is found between the 3.28 µm subfeature and the aliphatic hydrocarbon band at 3.4 µm, implying similar environmental
conditions for the formation of these molecular carriers. Possible interpretations are discussed
in terms of molecular stability and destruction pathways of carbonaceous interstellar species.

Figure 1: Spectroscopic fitting used in this work. Original data is shown as a solid gray line, and the overall
fit is shown by the black dot-dashed line. Note the inclusion of two sub-features (shown in gray) to match
the profile of the 3.3 µm band.

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