Molecules as probes of activity in obscured luminous galaxies
S. Aalto1
1Department of Earth and Space Science, Onsala Observatory, Chalmers University ofTechnology, SE-439 92 Onsala, Sweden
Chemistry of the molecular interstellar medium (ISM) can be used to distinguish between
AGN and starburst-driven activity in heavily extincted nuclei. It is a potentially powerfultool to help track evolution of activity, probing the interplay between activity and ISM
properties and to explore the starburst-AGN relation. For example, the chemistry of the ISM
near an intense X-ray source such as an AGN (an XDR, X-ray Dominated Region) is
expected to show a different chemical signature than that of an evolved starburst
characterized by PDRs (Photon Dominated Regions). Young star formation dominated bydense, warm and shielded gas will have properties different from both XDRs and PDRs.
Interpreting extragalactic mm- and sub-mm molecular line emission involves disentangling
excitation and radiative transfer effects (e.g. optical depth, radiative excitation, absorption)from those of chemistry. As an example of the challenges and rewards of studies of themolecular ISM of luminous galaxies I will discuss the prototypical ULIRG (Ultra Luminous
IR Galaxy) Arp220 and observations/models of HNC, HCO+and H3+O. Furthermore, theunusually luminous HC3N line emission towards the IR-bright, but otherwise inconspicuous,
S0 galaxy NGC4418 (Fig. 1) will be discussed. Herschel studies of IR-luminous galaxies will
be presented as well as a recent 3-mm line survey carried out with the IRAM 30m EMIR
instrument.
References[1][2]

Costagliola, F. & Aalto, S., 2010, S., A&A, 515, 71
Evans, A., et al 2003, AJ, 125, 2341

Figure 1: Sample HC3N spectra and rotational diagram of NGC4418. Note the prominent vibrational lines andthe multiple temperature components in the raotational diagram.

AKARI observations of ice absorption bands towards edge-on YSOs
Y. Aikawa1, D. Kamuro1, I. Sakon2, Y. Itoh1, N. Irimichi1, H. Terada3, J.A. Noble4,
K.M. Potoppidan5, M. Tamura3
1

Departmen of Earth and Planetary Sciences, Kobe Univ, Japan,
2
Departmen of Astronomy, University of Tokyo, Japan,
3
National Astronomical Observatory of Japan,
4
Department of Physics, Univ. of Strathclyde, Scotland,5
California Institute of Technology, USA,

Circumstellar disks and envelopes of low-mass young stellar objects (YSOs) containsignificant amount of ice. Such icy material will evolve to be volatile components of planetarysystems, such as comets in our solar system. In order to investigate the composition andevolution of circumstellar ice of low-mass YSOs, we have observed ice absorption bands atnear infrared (NIR) towards 8 YSOs ranging from class 0 to class II, among which 7 areassociated with edge-on disks.
Slit-less spectroscopic observations are performed using grism mode of Infrared Camera(IRC) on board AKARI, which enables us to obtain full NIR spectra from 2.5 μm to 5 μm,
including the CO2 band and blue wing of the H2O band, which are not accessible from theground. We developed procedures to reduce the spectra of targets with nebulousity. The
spectra are fitted by the polynomial to derive the absorption spectrum, which then is fitted by
the laboratory database of ice absorption bands considering the instrumental line profile andspectrum resolution of the grism.
Towards the Class 0-I sources, absorption bands of H2O, CO2, CO and XCN are clearly
detected. Column density ratios of CO2 ice and CO ice relative to H2O ice are 15-28 % and13-46 %, respectively. If XCN is OCN-, its column density is as high as 2-6 % relative to H2O
ice. Weak features of 13CO2, HDO, C-H band, and gaseous CO are detected as well. OCS ice
absorption is detected towards IRC-L1041-2. Towards class II stars, H2O ice band is detected.
We also detected H2O ice, CO2 ice and tentative CO gas features of the foregroundcomponent of class II stars.

Spectral Lines of Carbon Chain Molecules in a Star Forming Region L1527
between 29 and 90 GHz
M. Araki,1 N. Koshikawa,1 H. Yamabe,1 H. Umeki,1 K. Tsukiyama,1 S. Takano,2 N. Kuze3
1

Department of Chemistry, Faculty of Science Division I, Tokyo University of Science, 1-3
Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan
2
Nobeyama Radio Observatory and Graduate University for Advanced Studies, Minamimaki,
Minamisaku, Nagano 384-1305, Japan3
Department of Chemistry, Faculty of Science and Technology, Sophia University, 7-1
Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan

We have studied molecular spectral lines of carbon chain molecules in a star forming region
L1527 between 29 and 90 GHz by using the 45m telescope of the Nobeyama Radio
Observatory (NRO). H2CCO, HCCCHO, SO and isotopic species of HCN and HC3N havebeen detected for the first time in L1527.
Using integrated intensities of the detected rotational lines of JKa,Kc = 40,4-30,3, 41,4-31,3 and41,3 -31,2 of H2CCO, column densities of ortho and para H2CCO were estimated to be
3.8 × 1012 and 2.0 × 1012 cm-2, respectively, with an assumption of an excitation temperatureof 12.3 K [1a]. These values give an ortho to para ratio of 1.8(-0.1, +0.7) which is less thanthe ortho to para ratio of 3.0 at the high temperature limit. The small ratio might suggest that
H2CCO in L1527 comes off from the grain surfaces.
Column densities of HC13CCN and HCC13CN were obtained based on the assumption of theexcitation temperature of 12.3 K [1a] as shown in Table 1. Isotopic ratios,[Normal Species]/[13C Species], were derived from a comparison with the reported column
density of the normal species HC3N [1b]. Since the isotopic ratios in L1527 were similar to
those in TMC-1 [2], the chemical reaction producing HC3N in L1527 can be similar to thosesuggested in TMC-1 as follows [2]:C2H2+ + HCN →HC3NH+ + H,
C2H2 + HCNH+ → HC3NH+ + H2,
C2H2 + CN →HC3N + H (dominant reaction).
Table 1: Column densities and isotopic ratios of HC3N in TMC-1 and L1527

Isotopic Species

Column Density(cm-2)

H13CCCN
HC13CCN
HCC13CN(2.0 ± 0.2) × 1012
(2.1 ± 0.2) × 1012
(2.9 ± 0.3) × 1012

H13CCCN
HC13CCN
HCC13CN

3.3 × 1011
5.8 × 1011

[Normal Species]/[13C Species]
TMC-1 [2]79 ±11
75 ±10
55 ±7
L1527
80 ±6
50 ±4

References[1] (a) Sakai et al., ApJ, 672, 371 (2008). (b) Sakai et al., ApJ, 702, 1025 (2009).
[2] Takano et al., A&A, 329, 1156 (1998).

The mesoscale morphologies of ice films: Porous and biomorphic forms of ice underastrophysical conditions
Julyan H. E. CartwrightInstituto Andaluz de Ciencias de la Tierra, CSIC–Universidad de Granada
Granada, Spain

I present the results of experiments in which we grow submicrometer- to millimeter-thick ice
ﬁlms at temperatures of 6 to 220 K at low pressures in situ in a cryo environmental scanningelectron microscope. We ﬁnd that ice ﬁlms show pronounced morphologies at the mesoscale
similar to those previously described in ﬁ lms of ceramics, semiconductors, and metals;
materials with quite different material properties to ice. Our experiments are aimed atrevealing the mesoscale morphologies of amorphous and crystalline ice with regard toastrophysical environments, as the conditions in which the ice ﬁlms grow in our experiments
are those under which exists most extraterrestrial ice. The porosity on the mesoscale of manyof the morphologies is notable in this regard; a further intriguing ﬁnding is that these ice ﬁlms
can emulate biological forms.

References[1]

JHE Cartwright, B Escribano, & CI Sainz-Díaz, Astrophysical Journal, 687, 1406-1414, 2008.

UV/EUV photolysis of polar and nonpolar molecules’ effect on methane containing ice
mixtureY.-J. Chen,1 C.-C. Chu,1 P.-Y. Huang,1 T.-S. Yih,1 W.-H. Ip,2 H.-S. Fung,3 and C.-Y. R. Wu4
1

Department of Physics, National Central University, Taiwan
Graduate Institute of Astronomy, National Central University, Taiwan
3
National Synchrotron Radiation Research Center, Taiwan
4Space Science Center and Department of Physics and Astronomy, University of Southern
California, USA
2

UV/EUV photolysis of N2+CH4, H2O+CH4 and N2+CH4+H2O ice mixtures at 17K have been
investigated in this work. IR spectra show that C2H6 and C3H8 production yields are slower in
nonpolar molecule (N2) containing ice mixtures, and lots of H atoms dissociated from CH4
molecules will recombine with CCCN molecules to form HNCCC in N2+CH4 ice mixture.
That makes the absorbance feature of HNCCC at 2205 cm-1 is stronger than CCCN at 2194
cm-1[1]. Besides, all CCN bearing molecules which were formed via UV/EUV photolysis of
N2+CH4 ice mixture converted into OCN- while polar molecule (H2O) was the starting
component of ice mixture. This result shows that CN bearing molecules prefer to interact withOH radical to form HNCO and subsequently interacts with H2O to form OCN-.

Figure 1: IR spectra of N2:CH4= 1:1 and N2:CH4:H2O = 1:1:1 after UV/EUV irradiation.

References[1] J. B. Halpern, G. E. Miller, H. Okabe, and W. Nottingham, 1988, Journal of Photochemistry andPhotobiology, A: Chemistry 42, 63.
[2] R. L. Hudson and M. H. Moore, 2004, ICARUS 172, 466.

HOCO+ toward Sgr B2 Complex
S. Deguchi1
1

Nobeyama Radio Observatory/ National Astronomical Observatory, JAPANA number of rotational lines of protonated carbon dioxide, HOCO+, have been observed
mostly at frequencies above 80 GHz in interstellar clouds. In this conference, we report theidentification of the lowest rotational transition 101-000 of HOCO+ at 21.383 GHz toward
Sgr B2, and a detection of emission of the next lowest transition 202-101 at 42.766 GHz
toward GCM0.77-0.06, using the Nobeyama 45m telescope.
Protonated carbon dioxide (HOCO+) has been identified in interstellar clouds since 1981 [1].
Although millimeter-wave thermal lines of this molecule are considerably weak and difficult
to detect in general, they are found in a few different environments in the Galaxy, forexample, toward the translucent clouds [2], in the Galactic Center [3], and toward alow-mass protostar [4], and moreover, toward the center of the galaxy NGC 253 [5]. This
molecular ion can be used as a measure of the abundance of CO2 which is not observabledirectly at radio wavelengths.
Several years ago, we have identified the weak thermal line U42.767 seen toward the Galactic
Center to the HOCO+ 202-101 transition, and made a map of this thermal line in the 30' x 30'
area of Sgr A* [6]. Because the frequency of this transition is close to the frequency of the
SiO v=2 J=1-0 transition (42.821 GHz), so that the observations can simultaneously be madewith SiO maser surveys with the Nobeyama 45-m telescope [7,8].
No observation of the lowest rotational transition 101-000 of HOCO+ has been reported
till today, because the line is severely blended with a recombination line H67alpha at 21.386
GHz. We reanalyzed the spectral line data toward Sgr B2 complex at this frequency, whichwere taken using Nobeyama 45m telescope in 2004 and were archived. Subtracting the
averaged line profile of H66alpha and H68alpha from the H67alpha profile, we obtained thedifference spectrum, which shows a clear emission of the 101-000 transition of HOCO+. We
also report the detection of unexpectedly strong HOCO+ emission toward the Galactic Centermolecular cloud GCM0.77-0.06 at 42.766 GHz.
References[1] P. Thaddeus, M. Guelin, & R. A. Linke, 1981, ApJ, 246, L41S.
[2]
B.E. Turner, R. Terzieva, & E. Herbst, 1999, ApJ, 518, 699[3]
Y. C. Minh, et al. . 2005, New Astronomy, 10, 425[4]
N. Sakai, T. Sakai, Y. Aikawa, & S. Yamamoto 2008, ApJ, 675, L89[5]
S. Martin et al. ApJS, 164, 450[6]S. Deguchi, A. Miyazaki, & Y.C. Minh, 2006, PASJ, 58, 979[7]
S. Deguchi, et al. PASJ, 56, 261[8]
T. Fujii, et al. 2006, PASJ, 58, 529

A hybrid moment equation approach to gas-grain chemistry
Fujun Du1, Bérengère Parise1
1

Max-Planck Institute for Radio Astronomy, Germany

Complementary to the gas phase chemistry, chemical processes happening on the grainsurfaces are important for the overall interstellar matter repository. Due to their discrete andstochastic nature, however, usually surface chemistry cannot be accurately modeled by therate equations. Various methods have been proposed, including the modified rate equation
approach (Caselli et al. 1998; Garrod 2008), master equation approach with cutoff(Stantcheva et al. 2002), moment equation approach with cutoff (Lipshtat and Biham 2003;
Barzel and Biham 2007), multiplane approach (Barzel et al. 2007), and the exact Monte Carloapproach (Vasyunin et al. 2009). The Monte Carlo approach would produce the most accurate
results if it is repeated for many times; however, it is computationally heavy, and eventually
impractical when a large chemical network is being modeled. On the other hand, a consistentand automatic algorithm is needed to handle a generic system in which both the gas phase andgrain surface processes are included. In the present work, we propose a moment equation
approach in which the generating function machinery is used to generate the equations
automatically (up to any prescribed order), and a cut-off-and-switch scheme is implemented
to approximate the infinite system of equations. Comparisons are made between the results ofthis method and those from the exact Monte Carlo simulations for several commonly usedsystems. The agreement is usually satisfactory, while the speed of our method is not muchslower than the rate equation approach. Further issues include the numerical stability of thismethod (when higher order moments are included), how to control the errors quantitatively,
and how to select those mostly needed terms to limit the number of variables and lower thecomputational burden.

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

B. Barzel, & O. Bihm, 2007, ApJ 658, L37
B. Barzel, & O. Biham, & R. Kupferman, 2007, Phys. Rev. E., 76, 026703
P. Caselli, T. I. Hasegawa, & Eric Herbst, 1998, ApJ 495, 309
R. T. Garrod, 2008, A&A 491, 239
A. Lipshtat, & O. Biham, 2003, A&A 400, 585
T. Stantcheva, V.I. Shematovich, & E. Herbst, 2002, A&A 391, 1069
A. I. Vasyunin, D.A. Semenov, D.S. Wiebe, & Th. Henning, 2009, ApJ, 691, 1459

Near-Infrared Image of Circular Polarization in the Orion Nebula
T. Fukue, 1 M. Tamura, 1,2 R. Kandori, 1 N. Kusakabe, 1 J. H. Hough, 3 P. W. Lucas, 3 J.
Bailey, 4 D. C. B. Whittet, 5 Y. Nakajima, 1 J. Hashimoto, 1 and T. Nagata 6
1

National Astronomical Observatory of Japan, Japan
2
Graduate University of Advanced Science, Japan
3
Centre for Astrophysics Research, Science and Technology Research Institute, University of
Hertfordshire, UK
4
School of Physics, University of New South Wales, Australia
5
New York Center for Astrobiology and Department of Physics and Astronomy, Rensselaer
Polytechnic Institute, USA
6
Department of Astronomy, Kyoto University, Japan
We report a wide image of circular polarization (CP) in the Orion nebula. Near infraredcircular polarimetry of the nebula was conducted using the SIRIUS camera [1] and its
polarimeter (SIRPOL) on the 1.4-m IRSF telescope at the South African Astronomical
Observatory.
The CP image in the Ks band (2.14 μm) reveals that a high CP region is spatially extended(~0.4 pc) around the massive star-forming region, the Orion BecklinNeugebauer(BN)/Kleinman-Low(KL) nebula [2]. The degrees of CP range from +17% to−5%. On the other hand, other regions, including the linearly polarized Orion bar, show no
significant CP, in contrast with the linear polarization (LP) image [3].
The detected degrees of CP are the highest among the previously observed young stellar
objects (YSOs). To explore the production mechanism of CP in a YSO, we investigate
correlations of CP, LP, and H - Ks color, in the BN/KL region from the obtained images [4].
H - Ks color representing extinction is well correlated with CP. We derive a simple relation
between dichroic extinction, color excess, CP, and LP, assuming a model for a YSO withaligned non-spherical dust grains. The observed correlation between the Stokes parameters
and the color excess agrees with the derived relation, and suggests a major contribution ofdichroic extinction to the production of CP in this region.
From the viewpoint of astrobiology, our results also provide the implication for the origin of
the terrestrial life. The terrestrial living material consists almost exclusively of one enantiomer,
left-handed amino acids and right-handed sugars. The origin of biomolecular homochirality isa longstanding mystery that is critical to understanding the origin and development of life.
Our result reveals that the significant CP extends over a region ∼400 times the size of the solar
system [2]. If our solar system formed in a massive star-forming region like the Orion nebula
and was irradiated by CP radiation, then enantiomeric excesses could have been induced,
through asymmetric photochemistry, in the parent bodies of the meteorites. These would be
subsequently delivered to Earth, and could then have played a role in the development of
biological homochirality on Earth.
References
[1]
[2]
[3]
[4]

T. Nagayama et al., 2003, Proc. SPIE, 4841, 459.
T. Fukue et al., 2010, Orig Life Evol Biosph, 40, 335.
M. Tamura et al., 2006, ApJ, 649, 29.
T. Fukue et al., 2009, ApJ, 692, 88.

Carbon Isotope and Isotopomer Fractionation in Cold Dense Cloud Cores
K. Furuya, 1 Y. Aikawa, 1 N. Sakai, 2 and S. Yamamoto 2
1

Department of Earth and Planetary Sciences, Kobe University, Japan2
Department of Physics, The University of Tokyo, Japan13

C should be useful to investigate chemistry of carbon bearing species. Recent
observations in TMC-1 indicated that the molecular abundances of carbon isotopomers aredifferent. Takano et al. (1998) observed HC3N and found HCC13CN is more abundant than
HC13CCN and H13CCCN, which indicates three carbon atoms are not equivalent in HC3N.
Sakai et al. (2007; 2010) reported the abundance ratios of C13CS/13CCS = 4.2 andCCH/13CCH = 1.6. Again, these results indicate two carbon atoms are not equivalent in
CCS and CCH. They pointed out there are two possible processes to cause thesefractionation: (i) the formation path ways of the species and (ii) the exchange of the 13C
position after formation of molecules by isotopomer-exchange reactions.
We construct the gas-grain chemical network model which includes carbon isotopes (12C
and 13C). Temporal variations of molecular abundances, the carbon isotope ratios(12CX/13CX) and the isotopomer ratios (12C13CX/13C12CX) of CCH and CCS in cold dense
cloud cores are investigated by numerical calculations.
We reproduce the observed C13CH/13CCH ratio in TMC-1; isotopomer-exchange
reaction, 13CCH + H -> C13CH + H. However, the C13CS/13CCS ratio is lower thanobserved in TMC-1. We propose the isotopomer-exchange reaction,
13
CCS + H -> C13CS + H + 15K. In the model with this reaction, we reproduce theobserved C13CS/13CCS, CCS/C13CS and CCS/13CCS ratio simultaneously.

Figure 1: Temporal variation of (a) isotopomer ratios: the C13CS/13CCS ratio and (b) isotope ratios of
CCS: the CCS/13CCS and CCS/C13CS ratios. Solid lines show ratios in the model with the reaction,
13
CCS + H -> C13CS + H + 15K. Dashed line shows the isotope ratio of CCS in the model without thereaction. The density is nH = 105 cm-3.

References
[1]
[2]
[3]

Takano, S. et al. 1998, A&A, 329, 1156.
Sakai, N., Ikeda, M. & Morita, M., et al. 2007, ApJ, 663, 1174.
Sakai, N., Saruwatari, O., Sakai, T., Takano, S., & Yamamoto, S. 2010, A&A, 512, 10.

Dissociative Recombination and the build-up of complex molecules in the Interstellar
Medium1
1
1
W. D. Geppert, M. Hamberg , E. Vigren , R. D. Thomas1, V. Zhaunerchyk1, E. S. Wirström2, C. M.
Persson2b, T. J. Millar3, J. Semaniak4 M. Kamińska4, F. Österdahl1, J. H. Black2, Å. Hjalmarson2, P.
Bergman2, M. Holmgren2, F. Hellberg5, and M. Larsson1
1

Stockholm University, Department of Physics, Roslagstullbacken 21, SE-10691
Stockholm, Sweden
2
Onsala Space Observatory, SE-439 92 Onsala, Sweden
3
Queen’s University Belfast, University Road, Belfast, BT7 1NN, UK
4
Institute of Physics, Świętokrzyska Academy, PL-25406, Kielce, Poland
5
Manne Siegbahn Laboratory, Frescativägen 24, SE-104 05 Stockholm, Sweden
methanol, ethanol, dimethyl ether and formic acid are produced in the gas-phase or on grain surfaces.
As gas-gas production pathways very often ion-neutral reactions leading to the protonated form of thespecies followed by dissociative recombination to yield the final product have been invoked.
In the case of methanol, a feasible gas-phase production process is unlikely. The rate of radiative
association of CH3+ and H2O leading to CH3OH2+ has been found to be far to low to explain theobserved methanol abundances [1] and, on top of that, only a minor fraction of methanol (3 %) is
produced in the dissociative recombination of the latter ion [2]. Introduction of these new findings into
state-of-the art model calculations of dark clouds yielded that the proposed gas-phase mechanism is by
far insufficient to explain the observed methanol abundances. On the other hand, successivehydrogenation of CO on icy grain surface by H atoms has been found to produce methanol [3].

Figure 1: Spectra of the 2-1 rotational line group of 13CH3OH (black) and 12CH3OH (gray) around 96 GHz

It now remains to be proven by direct observation that interstellar methanol really originates fromgrain surfaces. This can be done by the so-called, isotope labelling a posteriori, which was firstsuggested by Charnley et al. [4]. The method is based on the fact that 13C is preferably accumulated in
CO at low temperature, which in turn results in a 13C deficiency in other molecules forming from ionneutral reactions in the gas-phase [5]). Assuming that this selective fractionation remains unaltered by
the processes of adsorption and desorption, the 12C/13C ratio in various molecules could be used to
distinguish between formation from CO on cold grains and gas-phase formation.
We therefore performed observations of the 12C/13C ratio for C18O and methanol in several massive
young stellar objects, one pair of compact HII regions and one source hosting several young stellar
objects. The 2-1 rotational line groups of the 2 isotopomers around 96 GHz were observed using the
20m telescope at Onsala Space Observatory. (see Fig. 1). With one exception (where the 12C moleculelines are very probably optically thick) the agreement of the 12C/13C ratio on the two compounds is
excellent. This points to a surface origin of interstellar methanol, which is also corroborated by the factthat a strong correlation of abundances between methanol and formaldehyde has been found in several
star-forming regions [6].
Furthermore, the role of dissociative recombination in the formation of other, more complex
molecules detected in star-forming regions like ethanol, dimethyl ether and ethanol will be discussed.
References[1] D. Gerlich, and M. Smith, 2006, Phys. Scripta, 73,[2] W. D. Geppert et al., 2006, Faraday Discuss. 133, 177H. Shimauma, K. Pingu, & S. Miyauchi,
2008, ApJ 575, 1100 .
[3] Fuchs, G. W. et al. 2009, A & A 505, 629[4] S. B. Charnley et al., 2004, MNRAS 347, 157[5] W. D. Langer, T. E.Graedel, M. A Frerking & P. B. Armentrout, 1984, Ap J., 277, 581[6] Bisschop, S. E. Ph. D. thesis, Leiden University 2007

Formation of oxygen molecules following vacuum ultraviolet photodissociation of
amorphous solid water
T. Hama,1 M. Yokoyama,2 A. Yabushita,2 and M. Kawasaki,21Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan.
2
Department of Molecular Engineering, Kyoto University, Kyoto 615-8510, JapanThe effect of radiation on water ice has intrigued many scientists in the fields of interstellar
chemistry and planetary ice science as well as reaction dynamics, since water is the
predominant component of interstellar icy grain mantles in dense molecular clouds and small
solar system bodies such as comets. Oxygen molecule is known to be a product when water
ice is irradiated with photons, electrons, or with energetic ions. These experimental studies
indicate that VUV photodissociation of amorphous solid water (ASW) leads to secondary
reactions that result in molecular oxygen formation on or in ASW. Photodissociation of H2O
in the first absorption band of water ice (130–165 nm) involves mainly two primary processes.
H2O + hν Æ H + OH(v=0 and 1)
H2O + hν Æ H2 + O(1D)

(1)
(2)

For the electronically ground O(3P) production, two different formation mechanisms were
proposed: the exothermic recombination reaction of OH, and the photodissociation of OH on
the ASW surface.[1]OH + OH Æ H2O + O(3P)
OH + hν Æ H + O(3P)

ΔH = -67 kJ mol-1

(3)
(4)

From the fact that OH(v=0 and 1) and O(3P) are formed with large excess energy via reactions(1), (3) and (4), O2(X3Σg-) and O2(a1Δg) can be produced via subsequent reactions (5) and (6)in the 157 nm photolysis of ASW.[2]OH + O(3P) Æ O2(X3Σg-) + H
OH + O(3P) Æ O2(a1Δg) + H

ΔH = -68 kJ mol-1
ΔH = 26 kJ mol-1

(5)
(6)

Measurements of the translational and internal energy distributions of the photoproducts
generated from photodissocaiton of ASW allow assessment of possible secondary reactions
on/in ASW from reaction dynamics point of view. In the present work, we have investigatedthe kinetic and internal energy distributions of O2(X3Σg-, v=0) and O2(a1Δg, v=0) following
157 nm photodissociation of ASW at 90 K using the resonance-enhanced multiphotonionization (REMPI) method.[3]References[1] T. Hama, A. Yabushita, M. Yokoyama, M. Kawasaki, and N. Watanabe, J. Chem. Phys. 131, 114511 (2009).
[2] S. T. Lunt, G. Marston, and R. P. Wayne, J. Chem. Sot. Faraday Trans. 2 84,899 (1988).
[3] T. Hama, M. Yokoyama, A. Yabushita, and M. Kawasaki, J. Chem. Phys. (2010) in press.

Modeling Chemistry in the Accretion Disk of an Active Galactic Nucleus
N. Harada,1 E. Herbst, 1,2,3 and T. Thompson 2,4
1

Department of Physics, The Ohio State University, U.S.A.
Department of Astronomy, The Ohio State University, U.S.A.
3
Department of Chemistry, The Ohio State University, U.S.A.
4
Center for Cosmology and Astro-Particle Physics, The Ohio State University, U.S.A.
2

Understanding the processes of galaxy formation, mass accretion onto a supermassive blackhole and its connection to star formation are of great interest in astrophysics. It is useful toknow the condition of the interstellar medium in different types of galaxies such as ultraluminous infrared galaxies (ULIRGs), active galactic nuclei (AGN), and starburst galaxies.
Some molecules have been proposed as probes of AGN/starburst activity in galaxies. For
example, Kohno [1] found that a higher HCO+/HCN intensity ratio is favored in starburst
galaxies than in AGN-dominant galaxies. Enhanced HCN and CN intensity and abundances
are observed in AGN-dominant galaxies. A higher HCN abundance and some complex
molecules are observed in ULIRGs [2][3].
We model the chemistry in the molecular disk around an AGN using the condition of NGC
1068. We include the ionization by X-rays from the AGN core, cosmic-rays from thesupernovae and stellar winds. The effect of UV-photons is also discussed. We used the OSU
high temperature chemical network [4]. X-ray penetration is dependent on the disk structure,
and we tried to vary this structure. In most cases, the effect of X-rays at radii >10pc can
produce slightly less than the observed abundance of CN over the total hydrogen, which is(0.2-1) x10-7 at the 70 pc scale[5]. The HCN abundance is enhanced with high temperature in
the inner disk, and our results produce equal to or more than the value suggested by Usero etal., which is (0.8-1) x10-7[6]. If there is a dense midplane that X-rays cannot penetrate into,
complex molecules such as C2H2 and HC3N, are enhanced at the very inner part of the AGNdisk due to the high temperature. The advent of ALMA will resolve some of these moleculesin higher resolution and may provide useful information on the disk structure and the starformation activities.

Figure 1: The fractional abundances of CN and HCN at different radius and height from the AGN core areshown.

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

K. Kohno, 2005. AIPC, 783, 203
F. Costagliola and S. Aalto, 2010, A&A, 515, 71
F. Lahuis et al., 2007, ApJ, 659, 296
N. Harada, E. Herbst, & V. Wakelam 2010. ApJ, in press
Garcia-Burillo et al. 2010. A&A, in press (astro-ph:1005.1263)
A. Usero et al. 2004, A&A. 419, 897

Some Early Results from the HIFI Instrument on the Herschel Space Observatory
E. Herbst1
1

Departments of Physics, Astronomy, & Chemistry, Ohio State University, Columbus, OH,
USA 43210

The Herschel Space Observatory was sent into orbit in May 2009 in order to study the sky inthe submillimeter-wave and far infrared. The observatory is now orbiting the earth at the socalled second Lagrangian point (L2) of the Earth-Sun system. The 3.5-meter dish sends
radiation to three detectors, one of which is a high spectral-resolution spectrometer known as
HIFI (Heterodyne Instrument for the Far Infrared), while the other two – PACS
(Photoconductor Array Camera and Spectrometer) and SPIRE (Spectral and Photometric
Imaging Receiver) – are cameras and imaging spectrometers. HIFI operates in 6 bands,
ranging from 480 GHz to over 1900 GHz in frequency. The first period of observations wasdevoted to 7 Key Programs, which had been selected before launch and involved many
astronomers and astrochemists, such as myself. Currently, proposals have been submitted forthe first open-time portion of the mission (OT1), with each proposal having a team of perhaps
10 people, far smaller than the make-up of the Key Program groups.
Molecular observations using HIFI consist of both emission and absorption line studies. At
the higher frequencies accessible to HIFI, critical densities for emission can be very large, andso absorption becomes competitive as long as there is a continuum to absorb. Emission lines
have been detected from the usual suspects, especially hot cores rich in weeds such as methyl
formate. Interestingly though, the density of lines is lower than seen at millimeter-wave
frequencies. Even in Orion KL, absorption can be seen against the quasi-continuum emission.
The absorption lines include those of HF, and two most improbable ions OH+ and H2O+,
which are known to react with abundant H2 on every collision. Models explaining their
existence indicate that the matter is in a most violent state.
For continuum sources more distant than Orion, such as the galactic center, absorption ispresent both from cooler portions of the primary source and from diffuse matter in the spiralarms between the galactic center and us. In fact, there can be so many sources that theabsorption spectra need not be resolved. Absorption studies of the spiral arm clouds show
CH+, CH, CN, CCH, HCO+, HF, OH+, H2O+, and H3O+; here, though, it is somewhat easierto understand the presence of the two strange ions if H >> H2 in abundance. A new molecule
detected is protonated HCl, or H2Cl+, although the density of its environment is unclear.
Although water is a prosaic molecule, its detection and study are clearly important for
astrobiological considerations. Deuterated isotopomers seen in the spiral arm clouds include
ND and D2O. Although detailed gas-grain PDR models have not yet been run, it is difficult tounderstand the high abundance of ammonia without including surface chemistry. From themeasurement of diverse ortho/para ratios for H2O, H2O+, D2O, and NH3, astrochemists hopeto understand the physical conditions better, although the analysis of ortho/para ratios is itself
a source of much debate. These and other important studies in old stars and external galaxies
will be discussed as time permits.

Ammonia formation by the successive hydrogenation of N atom trapped solid N2
at low temperature
H. Hidaka, M. Watanabe, A. Kouchi, and N. Watanabe
Institute of Low Temperature Science, Hokkaido University, Japan
A high abundance of ammonia molecules (NH3) has been observed in the gas phase but alsosolid phase in molecular clouds. In the gas phase reaction, the combination process of thesuccessive H atom abstraction reactions
N+ + H2 → NH+ + H
NH+ + H2 → NH2+ + H
NH2+ + H2 → NH3+ + H
NH3+ + H2 → NH4+ + H
and the dissociative recombination reaction
NH4+ + e- → NH3 + H
has been proposed as the formation process of NH3. However, it was indicated that thisprocess is inefficient especially in cold molecular clouds [1], because the first abstraction
reaction were reported to the endothermic reaction [2,3]. In the gas-grain reactions, thesuccessive hydrogenation of N atom
+H

+H

+H

N → NH → NH2 → NH3
has been proposed. Since the grain (solid)
surface performs as the third body and adsorbs
excess energy of the chemical reactions, these
simple addition reactions can proceed. In
addition, these reactions are predicted the fast
reactions due to the radical-radical reaction.
Thus, it has been expected that the highabundance of NH3 requires the synthesis on thegrain surfaces. However, the formation of NH3
by the surface reactions has been little
conducted quantitatively.
We performed the experiments of the NH3formation by the H atoms exposure of N atoms
in solid N2 at 10 K. The formed NH3 wasobserved by the Fourier transform infraredabsorption spectrometry. We will discuss theformation mechanism of NH3 on/in solid N2 at
low temperature.
Figure 1: (top) Infrared absorption spectra forreference of solid NH3 at 10 K. (bottom) Absorption
spectra of the formed NH3 by the H atoms exposureof N atoms in solid N2 at 10 K. Dashed lines indicate
the identified absorption bands of NH3.
References[1]
E. T. Galloway & E. Herbst, 1989, Astron. Astrophys. 211, 413.
[2]
J. B. Marquette, B. R. Rowe, G. Dupeyrat, & E. Roueff, 1985, Astron. Astrophys. 147, 115.
[3]Su-hong Ge, Xin-lu Cheng, Xiang-dong Yang, Zi-jiang Liu, & Wei Wang, 2006, Icarus 183, 153.

Extremely high-velocity HCN emission from L1448C
N. Hirano,1 N. Ohashi, 1 and S. Takakuwa 1
1

Academia Sinica, Institute of Astronomy & Astrophysics, Taiwan

A class 0 protostar L1448C was mapped with the SMA in the HCN J=4–3, CS J=7–6, HCO+
J=4–3, SO JK=88–77, and 29SiO J=8–7 lines at an angular resolution of 2 arcsecond. The HCN,
CS and HCO+ emission mainly comes from three regions; one is centered at the position of
the northern protostar L1448C(N), the second one is around the position of anotherprotostellar souce L1448C(S), and the third one is at ~7" south of L1448C(S).
The HCN spectra observed around L1448C(N) show broad wings that extends to ±30 km s-1
from the cloud systemic velocity and separate secondary peaks at extremely high velocities(EHV) of ±50 km s-1. The terminal velocity of the EHV HCN emission is comparable to thoseof the SiO J=8–7 and CO J=3–2 [1]. However, the EHV HCN emission is localized on thecompact region of ±2" from the protostar, and does not show the elongated jet-likemorphology. The EHV emission is also shown in the SO and 29SiO lines. The spatial
distributions of the EHV emission in these lines are elongated along the jet axis, suggestingthat these components are the dense part of the jet at the base. The CS and HCO+ lines aremuch narrower than the HCN line, and show no hint of EHV component.
The HCN line observed near L1448C(S) shows a steep edge at the cloud systemic velocity
and a broad redshifted wing that extends to +60 km s-1. This line profile strongly suggest thatthe dynamical interaction between the energetic outflow from L1448C(N) and dense gas
envelope around L1448C(S). The SO and 29SiO lines observed here exhibit EHV component
at +60 km s-1 without lower velocity wing component, suggesting that the emission of theselines arises from the jet impacting on the dense gas. On the other hand, the CS and HCO+
lines exhibit narrow line width of ~2 km s-1 centered at the systemic velocity, and are likely
to come from the L1448C(S) envelope.
The third component at ~7" south of L1448C(S) is seen in the maps of HCN, CS, and HCO+.
As in the case of the L1448C(S) component, this component appears near the cloud systemic
velocity in the CS and HCO+, while at ~10 km s-1 redshifted velocity in the HCN.
Our results suggest that the HCN emission is significantly enhanced in the regions where theenergetic jet traced by the SO and 29SiO lines impacts on the dense ambient gas observed in
the CS and HCO+ lines. The origin of the compact EHV HCN component might be the strong
shocks in the jet beam at the base.

References[1]

N. Hirano et al. 2010, ApJ, 717, 58.

Computational Molecular Spectroscopy: Fe-containing Molecules of Astrochemical Interest
Tsuneo Hirano,1,2 Umpei Nagashima,2 and Per Jensen3
1)
Ochanomizu University, Japan
2)
National Institute of Advanced Industrial Science and Technology, Japan3)

Physikalische und Theoretische Chemie, Bergische Universität, Germany

Although Fe is known to have a large cosmic abundance comparable to those of Mg and Si, theonly iron-containing molecules so far detected in the cosmic environment are FeH in sunspots [1]and FeO toward Sgr B2 [2,3]. In 1994, we made a preliminary ab initio calculation on FeCO asa candidate for observation in interstellar space [4], but attempts by Kasai et al to detect it inspace failed [5,6]. Then we started ab initio calculations on several Fe-containing molecules ofastrochemical interest, including FeC [7], FeN [8], FeS, FeCO, FeNC [9], FeCN [10], FeOH
[11,12].
We discuss here the molecular properties of 𝑋𝑋� 6∆ FeNC, 𝑋𝑋� 6∆ FeCN, and 𝑋𝑋� 6A’(6∆) FeOH.
The last two of these have not yet been observed spectroscopically, and hence the predicted
spectra are shown in Fig. 1 and Fig. 2, respectively. The ab initio calculations are done at thelevel of MR-SDCI+Q+ Erel/[Roos ANO (Fe), aug-cc-pVQZ (C, N, O, H)].
The equilibrium structuresof FeNC and FeCN are
linear. The equilibrium
structure of FeOH is bentwith a barrier of 273 cm-1
at linearity, which is just
above
the
bendingzero-point energy of 194
cm-1, so that 𝑋𝑋� 6A’ FeOH
is a quasi-linear molecule.
The geometrical constantsof these molecules are
given in Table 1.
The Fe atoms in thesethree molecules are boundto their ligands through anionic bond, so that thebending potentials areshallow and give large
amplitude bending motion.
We
havecalculatedro-vibrationally averaged
bond lengths for various

Fig. 1 Predicted spectra for the 𝑋𝑋� 6∆ FeCN: (a) rotation spectrum, (b) ν1(at 2153 cm-1), (c) ν2 (at 170 cm-1), and (d) ν3 (at 423 cm-1), simulated at
12 K [10].

Table 1 Ab initio calculated molecular constants at the MR-SDCI+Q+Erel level.
108 DJ/cm-1

Molecule

B0/cm-1

𝑋𝑋� 6∆ FeNC b)
Exp. [13]𝑋𝑋� 6∆ FeCN c)
𝑋𝑋� 6A’ FeOH d)

0.14274
4.84
0.14447(13)0.12380
4.12

re(M-ligand) re(C-N) or/Åre(O-H) / Å
1.93542.01(5), r0
2.04841.80591.18231.03(8), r0
1.1681
0.9520Bond angle/degrees
180.0
180.0
180.0
134.2

<ρ
� >0 (δρ� ) a)/degreesa) The bond angle deviation from linearity with quantum dynamical uncertainty in parentheses.
b) Ref. [9]. c) Ref. [10]. d) Refs. [11,12].

13(7)

10(5)
39(14)

vibrational states as expectation values in terms of variational MORBID
wavefunctions. The r0 structure andthe bond angle supplement <ρ� >0 (i.e.
the angle deviation from linearity)
thus determined are included in Table
1.
It should be noted that even for alinear molecule, whose equilibrium
structure is linear, the ro-vibrationallyaveragedstructuredeviates
substantially from linearity due to thelarge amplitude bending motion. Itshould also be noted that, for thequasi-linear molecule 𝑋𝑋� 6A’ FeOH,
the <ρ� >0 value is quite close to theequilibrium bond angle. Whether
the molecule is linear or quasi-linear
or bent can be distinguished by the
Yamada-Winnewisser quasilinearity
parameter γ0 [14],Fig. 2 Predicted spectra of the 6A’ (6∆) FeOH Renner-degeneratestates (at 10 K) [11].

E(𝑣𝑣 = |𝑙𝑙 | = 1) − E(𝑣𝑣 = |𝑙𝑙 | = 0)γ0 = 1 − 4 × E(𝑣𝑣 2= 2,2|𝑙𝑙 | = 0) −E(𝑣𝑣2 = 2|𝑙𝑙 |= 0) .
2

2

2

2

It was found that for the linear molecules FeNC and FeNC, γ0 ≈ −1.0, and for the quasi-linear
molecule FeOH, γ0 = 0.1. Thus, at the early stage of the analysis of the experimentallyobtained infrared spectrum, one can identify the relevant molecule being linear, or quasi-linear,or bent.
Another molecule we consider here is FeCO. Many spectroscopic studies have been reported
for 𝑋𝑋� 3Σ− FeCO (see ref. [15], for example), but none for a 5Σ− FeCO. Our recent prediction at
the MR-SDCI+Q+Erel/[Roos ANO (Fe, C, O)] level for the a 5Σ− FeCO is as follows. This is alinear molecule, with equilibrium structures re(Fe−C) = 1.843 Å, re(C−O) = 1.153 Å, ∠e(Fe-C-O)= 180°. The MORBID analysis gives ro-vibrationally averaged structures as r0(Fe−C) = 1.845 Å,r0(C−O) = 1.157 Å, and <ρ� >0 =9°(4°) with B0 = 0.13422 cm-1 (4023.7 MHz). γ0 = −1.0 as is
expected for a linear molecule. We think that it would be worthwhile to characterize thismolecule further spectroscopically and to search for it in interstellar space.
References.

[1] P.K. Caroll, P. McCormack, and S. O'Connor, Astrophys. J., 208, 903 (1976).
[2] C.M. Walmsley, R. Bachiller, G. Pineau des Forêts, and P. Schilke, Astrophys. J., 566, L109 (2002).
[3] R.S. Furuya, C.M. Walmsley, K. Nakanishi, P. Schilke, and R. Bachiller, A & A, 409, L21 (2003).
[4] K. Takano, E. Netabayashi, K. Ishii, K. Tanaka, and T. Hirano, Symposium on Molecular Structure, Japan,
Abstract, P. 412(1994).
[5] Y. Kasai and K. Obi, Y. Ohshima, Y. Endo, and K. Kawaguchi, J. Chem. Phys.,103,90 (1995).
[6] E. Kagi, Y. Kasai, H. Ungerechts, and K. Kawaguchi, Astrophys. J., 488, 766 (1997).
[7] S. S. Itono, T. Taketsugu, T. Hirano, and U. Nagashima, J. Chem. Phys., 115, 11213 (2001).
[8] P.M. Scheridan, L.M. Ziurys, and T. Hirano, Astrophys. J., 593, L141 (2003).
[9] T. Hirano, R. Okuda, U. Nagashima, V. Špirko, and P. Jensen, J. Mol. Spectrosc., 236, 234 (2006).
[10] T. Hirano, M. Amano, Y. Mitsui, S. S. Itono, R. Okuda, U. Nagashima, and P. Jensen, J. Mol. Spectrosc., 243,
267 (2007).
[11] T. Hirano, P.R. Bunker, S. Patchkovskii, U. Nagashima, and P. Jensen, J. Mol. Spectrosc., 256, 45 (2009).
[12] T. Hirano, U. Nagashima, G. Winnewisser, and P. Jensen, J. Chem. Phys., 132, 094303 (2010).
[13] J. Lie and P.J. Dagdigian, J. Chem. Phys., 114, 2137 (2001).
[14] K. Yamada and M. Winnewisser, Z. Naturforsch., 31a, 139-144 (1976); M. Winnewisser, B. P.Winnewisser, I. R.
Medvedev, F.C. De Lucia, S.C. Ross, and L.M. Bates, J. Mol. Struct., 798, 1 (2006).
[15] K. Tanaka, K. Sakaguchi and T. Tanaka, J. Chem. Phys., 106, 2118 (1997).

Far infrared imaging survey of the Chamaeleon region with AKARI: column density
maps of molecular and atomic clouds resolving star forming cores
N. Ikeda1, Y. Kitamura1, S. Takita1, 2, A. Kawamura3, and M. Ueno1
1

Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency
2
Graduate University for Advanced Studies
3
Nagoya University

Molecular clouds are the major form of interstellar matter in the Galaxy and are thebirthplaces of stars. It is thought that molecular clouds are formed from atomic clouds, whichhave densities of ~1 - 10 cm-3 and temperatures of ~ several×10 - 100 K, through the phasetransition process [1]. It is well known that the structures of molecular clouds are highly
hierarchical. Especially, the scale of 0.1 pc “core”, in which gravitational collapse into a staroccurs, is important for star formation. A recent study [2] reported that the core structures
have been already determined in relatively tenuous (104-3 cm-3) gas, strongly suggesting that theformation process of molecular cloud/core structures from atomic cloud is a key tounderstanding the origin of stars. Therefore, it is highly required to derive the column density
distributions of molecular and atomic clouds with spatial resolutions high enough to resolve
the cores. We carried out imaging observations toward the Chamaeleon star forming regions
by Far-Infrared Surveyor (FIS) [3] onboard AKARI satellite. In the FIS bands of 60 - 160
microns we separate thermal radiation from cold (~ 10 K) and warm (tens of kelvins) dust
components associated with the molecular and atomic clouds, respectively. With the spatial
resolutions in the FIS bands of 30 - 60 arcsec, we succeeded in the construction of themolecular/atomic column density maps, covering 210 pc2 with the linear resolution of 0.04 pc,
which is enough to resolve the cores in the region (160 pc; [5]). There are five subregions
named Cha I, II, III, Major Filament and Cha East [6]. Active star formations occur in Cha I
and II, while little star formation is known in the other regions. We found a significant
correlation between the star-formation activities and the ratio of the molecular to the atomic
cloud mass among the subregions: the ratio is almost unity for Cha I and II, but is 0.5 for Cha
III and 0.1 for the others. On the other hand, the column density histograms for the atomic
components in the subregions are similar to each other and the upper end of the histogramsare ~5-9×1020 cm-2, corresponds to ~0.2-0.4 mag for AV. Considering that UV flux is
responsible for molecular cloud formation, the observed low-extinction requires that theatomic component should be highly clumpy[6], and the core formation is probably related tothe clumpiness of the atomic clouds.
References
[1]
[2]
[3]
[4]
[5]
[6]

Inoue, T. & Inutsuka, S. 2009, ApJ, 704, 161
Ikeda, N. & Kitamura, Y. 2009, ApJ, 705, L95
Kawada, M. et al. 2007, PASJ, 59, 389
Whittet, D. C. B. et al. 1997, A&A, 327, 1194
Mizuno, A. et al. 2001, PASJ, 53, 1071
Ikeda, M. et al. 1999, ApJ, 527, L59

Microwave spectroscopy of 13CH3OH
Takanori Ito, Hirofumi Shintai, Wakako Nomura, Kaori Kobayashi, and Shozo Tsunekawa
Department of Physics, University of Toyama, Japan
CH3OH is one of the most known interstellar molecules. As it is quite abundant, it is no
doubt that its isotopologues are also good candidates as interstellar weeds. In this study, we
carried out a microwave spectroscopic study of 13CH3OH. Recommended rest frequencies
based on the reviewed previous microwave results are compiled by Xu and Lovas. However,many experimental data are missing and the excited torsional state is limited up to the firstexcited state. We wish to supplement the experimental data and revise the analysis.
The microwave experiments below and above 40 GHz were carried out with conventional
Stark- and source-modulation spectrometers, respectively at room temperature. Data up to
200 GHz and 215-225 GHz were accumulated without gaps. The bottom figure is an example
of our spectrum in the 215 GHz region, showing assigned lines as well as unassigned lines.
Analysis has been done with RAM Hamiltonian. The detailed molecular constants will bereported.
JKaKc = 845 ‐ 936 A

13CH OH3

vt = 0JKaKc = 422 ‐ 312 E

JKaKc = 844 ‐ 937 A

215500215600215700215800215900Frequency (MHz)Figure 1: The spectrum of

13

CH3OH in the 215 GHz region.

References[1]

Li-Hong Xu, F. J. Lovas, J. Phys. Chem. Ref. Data, 26(1) pp. 17-156 (1997)

216000

Low temperature ion-molecule reactions with drift tube mass spectrometer
K. Iwamoto and R. Shiba
Department of Chemistry, Osaka Prefecture University, Japan

Gas phase ion-molecule reactions are one of the important synthetic pathways for formationof complex molecules in the space. We have developed a new instrument to measure themobility of gas phase ions. The drift tube technique is extensively used to investigate not only
the transport properties of ions (mobility) but also the ion-molecule and charge transfer
reactions in the low collision energy range. The temperature variation is achieved by acryostat system in which the drift tube is integrated.
El-Shall et al.[1,2] studied about associative charge transfer (ACT) reactions inbenzene+/propene and benzene+/acetylene systems and suggesting that ACT reactions initiates
polymerization in cold astrochemical environments.
We have applied the drift tube mass spectrometer to investigation of ACT reactions andternary molecular reactions. We show the details of the low temperature drift tube and somepreliminary experimental results.

Refrigerator(300-17K)

Ion source Ion lens
(EI/CI)

Quadrupole mass filter(analyzer)
Detector

Drift Cell
Quadrupole mass filter(selector)

Figure 1: Schematic diagram of the low temperature ion drift tube mass spectrometer.

References[1][2]

Y. Ibrahim, M.M. Mautner and M. El-Shall, 2006, JPCA 110, 8585.
P.Momoh, A. Soliman, M.M. Mautner, A. Ricca and M. El-Shall, 2008, JACS 130, 12848.

The irradiation of methyl cyanide (CH3CN) ice at 15 K with 200 keV protons
S Jheeta1, D Fulvio2, ME Palumbo2, G Strazzulla2, NJ Mason1
1

Depart. of Physics & Astronomy, the Open University, Walton Hall, Milton Keynes,
England, UK

2

Istituto Nazionale di AstroFisica, Osservatorio Astrofisico di Catania, Catania, Italy

Contact: s.jheeta@open.ac.uk
Methyl cyanide (CH3CN) is the simplest of the organic nitriles found in theinterstellar medium (ISM). It was first identified in the molecular clouds, Sagittarius
Sgr A and Sgr B [1] through its emission lines in the vicinity of 2.7 mm from the J =6 → 5 transition. In 1974 it was also reported in comet Kohoutek [2]. CH3CN, hassince been detected in the Hale Bopp comet [3] and, as of 2009, there are no less than
58 hot molecular core objects in which CH3CN had been found [4]. Methyl cyanide
has also been discovered beyond the Milky Way, in the NGC 253 galaxy [5], whichlies in the local group of galaxies, some 10 million light-years from Earth. It has also
been detected in the ISM where it is thought to be made on the grain mantles [6].
In the ISM any methyl cyanide produced on such ice grains may be exposed to a wide
range of radiation which in turn may produce further chemical species. In order todetermine the possible chemical products of such irradiation in the ISM we have
prepared thin films of methyl cyanide at 15 K and exposed them to 200 keV protons
using the ion beam facility at the Osservatorio Astrofisico di Catania.
The following species were found to be synthesized during such irradiation; methyl
isocyanide (CH3NC), hydrogen cyanide (HCN/CN-), methylenimine (H2C=NH),
ketenimine (H2C=C=NH), cyanoacetylene (HCCCN), and methane (CH4). These
results and details of the possible production routes will be presented at theconference.
References
1.
2.
3.

4.

5.
6.

Solomon, P.M., et al., Detection of millimeter emission lines from interstellar
methyl cyanide. Astrophysical Journal, 1971. 168(3): p. L107.
Ulich, B.L. and E.K. Conklin, Detection of methyl cyanide in comet-Kohoutek.
Nature, 1974. 248(5444): p. 121-122.
Remijan, A.J., et al., The distribution, excitation, and formation of cometary
molecules: methanol, methyl cyanide, and ehtylene glycol. AstrophysicalJournal, 2008. 689(1): p. 613-621.
Purcell, C.R., et al., A CH3CN and HCO+ survey towards southern methanol
masers associated with star formation. Monthly Notices of the Royal
Astronomical Society, 2006. 367(2): p. 553-576.
Mauersberger, R., et al., Dense gas in nearby galaxies .5. multilevel studies of
CH3CCH and CH3CN. Astronomy and Astrophysics, 1991. 247(2): p. 307-314.
Hudson, R.L. and M.H. Moore. Reactions of nitriles in ice's relevant to Titan,
comets, and the interstellar medium: formation of cyanate ion, ketenimines,
and isonitriles. Icarus, 2004. 172(2): p. 466-478.

Experimental study of nucleation, coalescence and growth of nanoparticles
Yuki Kimura, Hitoshi Miura, and Katsuo Tsukamoto
Department of Earth and Planetary Materials Science, Tohoku University, Japan

Nucleation is a first step to form cosmic dust particles and is a beginning of their longevolutional history accompanying with stellar lives. Nucleation determines number,morphology, polymorph, size and size distribution of nanoparticles, which strongly affect tothe infrared spectra and also formation of molecules on their surface. Accordingly, nucleation
is fundamental process on the cosmic dust formation. When nanoparticles are formed directlyfrom gas phase in ejecta gas of evolved stars and possibly in a plume after energetic shock in
primitive solar nebula, at least first nanoparticles must condense homogeneously. Then, theyshould be condensed under supercooling with nonequilibrium state. In this situation, we
cannot apply general thermodynamic equilibrium to find formation sequence of mineralparticles. In fact, however, there is no quantitative experimental data concerning ahomogeneous condensation from a gas phase. Here, we will show a first achievement of insitu visualization of the environments during homogeneous nucleation and subsequent growthof nanoparticles in smoke experiment using Mach-Zehnder interferometer and attempt todetermine the homogeneous condensation temperature and supersaturation of several kinds ofmaterials in gas phase.
Figure 1 shows an example of our first smoke produced in newly constructed smoke chamber.
The smoke was produced by heating of a tungsten wire with 0.3 mmφ and 70 mm depth in a
mixture gas of Ar (9×103 Pa) and O2 (1×103 Pa). Tungsten has been evaporated as oxide at
the source temperature ~1600 K, which measured by pyrometer. Evaporated oxide molecules
are subsequently cooled following the convection current produced by hot source and WO3particles have been condensed and formed the smoke. Since there is no heterogeneous
nucleation cite, solid grains were obtained homogeneously from the gas cloud. The
evaporated tungsten oxide vapor is concentrated at the interface between interior WO3 vaporrich atmosphere and outer mixture gas. Their condensation temperature can be determinedfrom the interferogram. We observed the produced smoke particles using transmission
electron microscope and recognized the formation of WO3 single crystal nanoparticles with
20-200 nm in diameter.
We are trying to discuss using classical nucleation
theory and calculated the growth velocity using
Herz-Knudsen equation to this experimental result.
W wireAs the result, we found that the theory no longer
works in this nano-world and coalescence process,which is a process two different nanoparticles fused
together and make larger nanoparticle, after Figure 1: Typical interferometric image
nucleation is important to know the final product. In of smoke particles.
addition to the preliminary experiment using WO3,
experimental results concerning astronomicallyimportant materials, such as alumina, silica and iron,
will be shown in the presentation.

THE SOFT X-RAY INDUCED CHEMISTRY OF CO AND CH3OH IN WATER ICE
STUDIED BY NEXAFS
C. Laffon1, J. Lasne1, F. Bournel1, K. Schulte2, S. Lacombe3, Ph. Parent1
1

Laboratoire de Chimie-Physique, Matière et Rayonnement, Université Pierre-et-Marie
Curie (UPMC-Univ Paris 06) and CNRS (UMR 7614), 11 rue Pierre-et-Marie-Curie,
75231 PARIS CEDEX 05-France.
2
MAX-lab, Lund University, PO Box 118, S-221 00 LUND-Sweden.
3
Laboratoire des Collisions Atomiques et Moléculaires, CNRS- LCAM, 91405 ORSAYCEDEX-France. Université Paris Sud 11- Bât 351, 91405 ORSAY CEDEX-France.
The irradiation of organic molecules in condensed water is an important process in a wide
variety of scientific areas, from the chemistry of the interstellar space medium[1] toradiobiology.[2] Aiming at characterizing these reactions at a molecular scale, we haverecently developed the use of the Near-Edge X-ray Absorption Spectroscopy (NEXAFS) forstudying irradiation of icy solutions. In this work, the soft X-ray induced chemistry of H2O,
CO and CH3OH and the effects of the water and nitric acid hydrate (HNO3.1.65H2O) matrix
on the photochemistry of CO and CH3OH have been investigated. For pure H2O, CO andCH3OH ices, the destruction rates are strongly limited by back reactions, leading to strikingly
high survival rates of these molecules upon the harsh irradiation conditions to which they
were submitted. We also evidence the interplay between the photochemical reactions of CO
and CH3OH and those of the matrix. The OH and O radicals released by the photolysis of H2O
and HNO3 react with the CO and CH3OH and their fragments, considerably reducing thesurvival rates, especially in presence of nitric acid, and dramatically enhancing the formationof CO2 at the expense of CO. Because NEXAFS spectroscopy allows identifying which
reactions are important among those possible, it emerges a simple picture of thephotochemical routes of CO and CH3OH in the H2O and HNO3/H2O environments.
[1] A. G. G. M. Tielens and W. Hagen, Astron. Astrophys., 114, 245 (1982)[2] K. Fujii, N. Shikazono and A. Yokoya, J. Phys. Chem. B, 113, 16007 (2009).

SMA Observations toward the Massive Star-forming Core MM1 of W75N
Y. C. Minh,1 S.-Y. Liu, 2 Y.-N. Su, 2 and H.-R. Chen 3
1

Korea Astronomy and Space Science Institute (KASI), Daejeon, Korea
Academia Sinica, Institute of Astronomy and Astrophysics (ASIAA), Taipei, Taiwan
3
Institute of Astronomy & Department of Physics, Nat'l Tsing Hua Univ., Hsinchu, Taiwan
2

The massive star-forming core MM1 of W75N was observed using the Submillimeter Array(SMA) with ~ 1" and 2" spatial resolutions at 230 and 340 GHz, respectively. From the 230
GHz continuum we found that the MM1 core consists of two sources, separated by about 1":
MM1a (~0.6 Mo) and MM1b (~1.4 Mo), located near radio continuum sources VLA 2/VLA 3
and VLA 1, respectively. Within MM1, two gas clumps have been found to be expanding
away from VLA 1 at about ±3 km/s, resulting from the latest star formation of the region.
Observed molecular lines show emission peaks at two positions, MM1a and MM1b: sulphurbearing species have emission peaks toward MM1a, but methanol and saturated species at
MM1b. We identified the high temperature (~200 K) gas towards MM1a and the hot core
towards MM1b. The SiO molecule is unique in having an emission peak exactly towards
VLA 2, probably tracing a shock powered by VLA 2. Observed sulphur-bearing species show
similar abundances both in MM1a and MM1b, whereas the methanol and saturated species
show significant abundance enhancement toward MM1b, by about an order of magnitude,
compared to MM1a.

Figure 1: (Left) Integrated intensity map of the H2CO 3(0,3)-2(0,2) line.Blue contours are for v=2.0-8.5
km/s, andred contours for v=8.5-16.0 km/s.Both contour levels start from 1.2 Jy/beam km/s and increase by
1.5 Jy/beam km/s. (Right) A schematic diagram of the MM1 core.

Line Survey Project of External Galaxies with NRO 45-m Telescope
T. Nakajima,1 S. Takano,1 K. Kohno,2 H. Inoue, 2 and the line survey team1

Nobeyama Radio Observatory, National Astronomical Observatory of Japan, Japan
2
Institute of Astronomy, The University of Tokyo, Japan

So far about 37 molecules have been detected in external galaxies. Since various galaxies withdifferent environments exist such as those with small or large amount of gas, with starburst
and/or Active Galactic Nucleus (AGN), and with interaction, etc., we expect that various
interesting phenomena could be observed in interstellar matter in galaxies. To study the effectof AGN on the circumnuclear molecular gas, further observations of molecular lines areindispensable. Therefore, we started a line survey in 3 mm band with the new receiver on the
NRO 45-m telescope [1] toward NGC 1068, which is one of the nearest AGN where apresence of X-ray dominated regions (XDRs) has been suggested (e.g., [2][3]). We can makea selective study of the effect of AGN, because a beam size of the 45-m telescope (~ 18″ at 86
GHz) is smaller than the size of circumnuclear starburst ring in NGC 1068 (d ~ 30″). This
project is still continuing but we report some of the results from the initial observations.
The observations at the 3 mm region (85.1-92.2 GHz and 96.5-98.4 GHz) were carriedout in February to May, 2009 and January to May, 2010. We successfully detected cyclicC3H2 (JKa,Kc = 21,2-10,1), C2H (N = 1-0) and H13CN (J = 1-0) for the first time in NGC 1068,
and HC15N (J = 1-0) and CH3OH (JK = 2K-1K) were tentatively detected. In addition, thedetection of CS (J = 2-1) has already been reported [4], but we detected for the first time witha single dish telescope in this galaxy. We are also observing NGC 253, which is the
prototypical nearby starburst galaxy, as a comparison to study the effect of AGN on molecularabundance. The following results were obtained about the C2H lines.
(1) Using the fine structure, the optical depths toward NGC 1068 and NGC 253 wereobtained to be less than 1. These molecular lines are optically thin in both galaxies.
(2) The column densities are estimated to be 0.9 x 1014 and 0.5 x 1015 cm-2, respectively,
assuming the excitation temperature of 30 K. The latter value is consistent with the value
obtained toward NGC 253 from the previous study [5].
We will report on detailed results of other molecules with our poster.

References
[1]
[2]
[3]

T. Nakajima, et al., 2008, PASJ 60, 435
A. Usero, et al., 2004, A&A 419, 897
K. Kohno, et al., 2008, Ap&SS, 313, 279

[4]
[5]

L. J. Tacconi, et al., 1997, Ap&SS 248, 59
S. Martín et al., 2006, ApJS, 164, 450

Formation of CO2 and H2CO3 through non-energetic surface reactions at low
temperatures.
Y. Oba,1 N. Watanabe,1 A. Kouchi,1 T. Hama,1 and V. Pirronello2
1

Institute of Low Temperature Science, Hokkaido University, Japan
2
DMFCI, Università di Catania, Italy

INTRODUCTION
Carbon dioxide (CO2) is one of the most abundant solid components in icy grain
mantles of dense molecular clouds. It is well known that CO2 can be synthesized from purecarbon monoxide (CO) or CO-containing ices through energetic processes such as UV
irradiation, ion irradiation, and electron irradiation [e.g. 1]. However, recent detections ofabundant CO2 in dense clouds observed toward background stars, in which the UV field isrelatively weak, suggest that some reactions without UV irradiation may also contribute to theCO2 formation in these environments [2]
In contrast to CO2, carbonic acid (H2CO3) has never been detected either in the gas
phase or solid phase in molecular clouds. However, it is considered that H2CO3 may have arole in acid-base chemistry, such as in reactions with NH3 to yield NH4+, in astrophysicalenvironments [3]. Therefore, elucidating the formation pathways of H2CO3 and its
astrophysical significance is necessary for understanding chemical reaction networks related
to the presence of CO in molecular clouds.
In the present study, we demonstrate formation of CO2 and H2CO3 through surface
reactions of CO with non-energetic OH radicals at low temperatures.
EXPERIMENTAL
Experiments were performed using the Apparatus for SUrface Reaction in Astrophysics(ASURA) system. ASURA consists of a main chamber, an atomic source, and a Fouriertransform infrared (FTIR) spectrometer. Hydroxyl (OH) radicals, produced by dissociatingwater molecules in microwave-induced plasma, were cooled down to 100 K prior to reactwith CO. OH and CO were codeposited onto an Al substrate (10–40 K) and the reaction
products were monitored in-situ by infrared reflection-absorption spectroscopy.
RESULTS
When CO molecules were simultaneously introduced together with OH radicals onto
the substrate, formation of CO2 was clearly identified in the reaction product even at 40 K. In
addition to CO2, several peaks were observed in the IR spectrum. It has been theoreticallydemonstrated that gas phase synthesis of CO2 by CO + OH proceeds through the following
pathways: CO + OH → trans-HOCO → cis-HOCO → CO2 + H [4]. Detection of both HOCO
radicals in the reaction product at 10 K further supports an assumption that CO2 formed
through the above reaction pathways in the present experiment.
After the sample was warmed up to 220 K, some peaks were still observed in the IR
spectrum, which were attributable to carbonic acid (H2CO3). Formation of H2CO3 was also
demonstrated by the temperature-programmed desorption spectra of the reaction product. It is
likely that H2CO3 formed through reactions of trans- and cis-HOCO radicals with OH.
The present study demonstrated that CO2 and H2CO3 can form inside dense molecular
clouds without external energy inputs from UV, ions, and electrons.
References
[1]
[2]
[3]
[4]

N. Watanabe, & A. Kouchi, 2002, ApJ, 567, 851.
E. A. Bergin et al., 2005, ApJ, 627, L33.
W. A. Schutte & R. K. Khanna, 2003, A&A, 398, 1049.
H.-G. Yu, J. T. Muckerman, and T. J. Sears, 2001, Chem. Phys. Lett., 349, 547.

DISCS: A spatially and spectroscopically resolved survey of chemistry inprotoplanetary disks
Karin Öberg, Chunhua Qi, Jeffrey Fogel, Edwin Bergin, David Wilner, Ilaria Pascucci,
Sean Andrews, Catherine Espaillat, Tim van Kempen
Protoplanetary disks connect protostars and extra-solar systems chemically and physically, with
implications for the composition of comets and planets both in our Solar System and in theincreasing number of extrasolar systems. To address the chemical evolution of these disks,
including their organic inventory, we are in the process of spatially resolving the abundancesof eight key molecules and ions – CO, HCO+ , DCO+ , N2 H+ , HCN, DCN, CN, H2 CO – in
14 protoplanetary disks using the Submillimeter Array (DISCS: the Disk Imaging Survey ofChemistry with the SMA, PI K. Öberg). The detection rates of minor species such as H2 CO
and N2 H+ are surprisingly high allowing us to directly compare the response of the chemistry– for example ionization rates, deuteration, signposts of photon dominated chemistry and ice
evaporation – to the physical processes active in disks. A range of physical disk environments isensured by including star+disk systems that span stellar spectral types from M1 to A0, ordersof magnitude different accretion luminosities and X-ray fluxes, and exhibit the full range of grain
evolution parameters found in disks. By combining the known physical structures of the diskswith our survey of simple chemical systems, we aim both toward characterizing the main driversof disk chemistry in the bulk of disk material and providing constraints on the physical processes
active during planet formation.

The evolving ice-gas interface during star- andplanet-formation
Karin Öberg
Complex organic molecules (>6 atoms) have been detected toward low- and high-mass
protostars, galactic center clouds, protostellar outflows and comets, demonstrating the existence of efficient astrophysical pathways to chemical complexity. The detected molecules
all reside in the gas. Yet many probably form on interstellar grains, in ices that evolvewith their environment and finally evaporate as the grains are heated by new-born stars
or by shocks. I will explore this ice evolution during star formation by combining Spitzer
spectra of the first, simple ices with laboratory simulations of UV induced ice photochemistry and with millimeter observations tracing complex ice evaporation. The experiments
show that UV irradiation of protostellar ices is efficient enough to explain the complex
molecule observations in so called protostellar ’hot cores’. Moreover, the experiments predict that before the onset of thermal evaporation close to the protostar, small fractionsof the complex ice will continuously evaporate non-thermally due to photodesorption,
resulting in gas-phase fingerprints of the ice composition as it evolves. To test this prediction and thus the ice origins of complex molecules in space, we searched for a numberof gas-phase complex organic molecules – HCOOCH3 , CH3 CHO, CH3 OCH3 , C2 H5 OH
and HCOCH2 OH – toward an ice-rich cloud core irradiated by a nearby protostar. The
observations have resulted in a modified scenario for complex ice formation and desorption during star formation. A key unknown is what happens to these molecules during
planet formation and I will end with showing some exciting results on the chemistry inprotoplanetary disks, acquired within the ongoing SMA legacy program DISCS.

1

Observational evidence for the asymmetrical dust clouds
around the peculiar SN impostor in the NGC 300.
R. Ohsawa,1I. Sakon1, T. Onaka1, M. Tanaka2, T. Moriya2,1,3, T. Nozawa2, K.Maeda2, K.
Nomoto2, N. Tominaga2,4, F. Usui5, H. Matsuhara5, T. Nakagawa5, and H. Murakami5
1Department of Astronomy/University of Tokyo, Japan
2Institute of the Physics and Mathematics of the Universe/University of Tokyo, Japan
3Research Center for the Early Universe/University of Tokyo, Japan
4Department of Physics/University of Konan, Japan
5Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Japan
Development of the observational instruments have allowed us to discover such a interesting
astronomical events as we have never seen. Among them, the supernova (SN) impostor,
which is an optical transient with the maximum luminosity intermediate between that ofclassical nova and of supernova, is one of the most interesting objects. Although several
studies have been made on SN impostors, the nature of them still remains to be discovered.
On 2008 May 14, an interesting optical transient was discovered around the nearby galaxy
NGC 300 by B. Monard[1] (hereafter NGC300OT). NGC300OT is different from other SN
imposters in that the progenitor of it was deeply dust-enshrouded[2] and it possibly produceda large amount of dust in its ejecta by comparing to its “twin” of SN 2008S[3]. We will
present the result of near-infrared (NIR) multi-epoch observation of NGC300OT on day 398
and 582 with the Infrared Camera (IRC) on board AKARI. NIR spectra indicated that the NIR
flux was mainly due to the thermal emission of hot dust, possibly newly-formed dust in theejecta. Assuming the isothermal dust cloud, we derived the temperature and the optical depthof the dust cloud by SED fits. Although the result showed that the dust cloud should be highly
optically thick at both epochs, no extinction in visible and UV had been observed in theformer studies. In order to resolve the discrepancy, we propose the asymmetric distribution of
the dust cloud. The asymmetric dust cloud also had been proposed by the former studies[4][5].
Our result strongly supports their conclusion in terms of NIR observation.

Figure 1: The NIR spectra and the results of photometry of NGC300OT

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

L. A. G. 2008, IAU Circ., 8946, 1.
J. L. Prieto 2008, ATel, 1550, 1.
M. T. Botticella, et al. 2009, MNRAS 398, 1041.
E. Berger et al. 2009, ApJ 699, 1850.
F. Patat et al. 2010, A&A 510, 108

Quantum chemical study of water effect for hydrogen abstraction reactions in low
temperature
Yoshihiro Osamura 1
1

Kanagawa Institute of Technology, Atsugi 243-0292, Japan

Hydrogen abstraction reactions and hydrogen transfer reactions are one of important
processes of molecular formation and destruction processes of interstellar molecules. We
have been studying the molecular processes of these reactions with small water clusters inorder to model the chemical reactions on icy grain surfaces in terms of quantum chemical
method. In this presentation, we show the differences of the molecular interactions between
various chemical species and small water clusters and how water molecules affect thepotential energy surfaces of the hydrogen abstraction reactions of hydrocarbons as well ashydrogen transfer reactions.
In order to obtain the interaction energies of various neutral radicals and small water clusters,
we have calculated the molecular geometries of CH3(H2O)n, OH(H2O)n, and H(H2O)n byusing hybrid density functional B3LYP method with 6-311G(d,p) basis functions. Figure 1
shows the optimized structures of CH3 radical, OH radical and H atom interacting with twowater molecules. The binding energies between radicals and water dimer are calculated to be
13, 52, and 2 kJ mol-1 for CH3, OH, and H species, respectively.

(a)

(b)

(c)

Figure 1. Optimized structures of (a) CH3(H2O)2, (b) OH(H2O)2, and (c) H(H2O)2 radicals.

The calculated potential energy surface of the chemical reaction of CH4 + H Æ CH3 + H2
shows the energy barrier of 25 kJ mol-1 and exothermic by 6 kJ mol-1. When single H2O
molecule adds to this system, its energy barrier found to be lower by 3 kJ mol-1. In the case of
CH4 + OH Æ CH3 + H2O reaction, the energy barrier 4 kJ mol-1 without H2O molecule iscalculated to become 7 kJ mol-1 with single H2O molecule interacting in the CH4 + OH
system. The change of the energy barriers by interacting H2O molecules depends on which
reactant species has strong interaction with H2O molecules. Figure 2 shows the structures oftransition states of two reactions and indicates the difference of the interacting site of H2O
molecule with reacting species.
(a)

(b)

Figure 2: Transition state structures of (a) CH4 + H and (b) CH4 + OH interacting with H2O molecule.

THEORETICAL INVESTIGATION OF THE FORMATION OF H2CO IN
THEINTERSTELLAR MEDIUM: A WATER ASSISTED REACTION
P. Peters1, D. Duflot1, L. Wiesenfeld2, C. Toubin1
1

Laboratoire de Physique des Lasers, Atomes et Molecules, (PhLAM), UMR CNRS 8523,
Université Lille 1
2
Laboratoire d’Astrophysique de Grenoble, (LAOG), UMR CNRS 5571, Université Joseph
Fourier
It is believed that Formaldehyde is formed on dust grains coated with ice within Molecular
Clouds.[1]With this in mind there have been several studies into the hydrogenation of CO toFormaldehyde (H2CO) reported within the literature.[2-5] These studies all consider thereaction scheme:
2H + CO → HCO +H → H2CO
However, it is equally plausible that the second Hydrogen may add to the Oxygen of theFormyl radical to generate trans-HCOH. This is of importance in the interstellar medium as
the gas phase barrier to isomerisation is large, and therefore will be unfavourable at low
temperatures. Schreiner et al [6] showed that even with such a high activation barrier that
HCOH does indeed isomerise at low temperatures to H2CO. They propose a tunnelingmechanism for the reaction, as it is evident that at 10 K the barrier is insurmountable. They
did not however look at the role that water may play within this isomerisation, our work,
based on quantum chemistry calculations, focuses on the role that water may play in thisreaction.

(1) A. G. G. M Tielens, W. Hagen, Astronomy and Astrophysics, 114, 245, (1982)(2) N. Watanabe, A. Kouchi, Progress in surface Science, 83, 439-489, (2008)(3) D. E. Woon, The Astrophysical Journal, 569, 541-548, (2002)(4) N. Watanabe, Proceedings IAU Symposium, 231, (2005)(5) T.P.M Goumans, C- Richard, A. Catlow, W. A . Brown, J. Chem. Phys., 128, 134709,(2008)(6) P.R. Schreiner, H.P. Reisenauer, F.C. Pickard IV, A.C. Simmonett, W.D. Allen, E.
Matyus, A.G. Csaszar, Nature, 453, 906-911, (2008).

HYDROGEN/DEUTERIUM EXCHANGESIN INTERSTELLAR/COMETARY ICE ANALOGS
Alexandre Ratajczak1,2, Eric Quirico2, Alexandre Faure1, Bernard Schmitt2,
Cecilia Ceccarelli1, Claudine Kahane1
1

Laboratoire d’Astrophysique de Grenoble, UMR 5571-CNRS, Université Joseph

Fourier, Grenoble, France
2

Laboratoire de Planétologie de Grenoble, UMR 5109-CNRS, Université Joseph Fourier,Grenoble, France
Despite the low cosmic abundance of deuterium (D/H ~ 10-5), high degrees of deuterium
enrichment in molecules are observed in star-forming regions with enhancements that canreach 13 orders of magnitude for multi-deuterated species [1]. High D/H ratios are also
observed in planets and small bodies of the solar system. Quantitative modelling of the
D/H ratios remains however hampered by the lack of appropriate chemical kinetics data.
In particular, the detailed mechanisms responsible for the observed enrichment disparities
between functional groups are currently poorly known. For example, there is significantly
more CH2DOH than CH3OD ([CH2DOH]/[CH3OD]>10) in low-mass protostars [2].
Various hypotheses have been suggested to explain this anomaly, but none is fully
convincing. In this work, we test a new hypothesis experimentally: the spontaneous
exchange between hydrogen and deuterium atoms in H2O:XD ice mixtures, where XD iseither CD3OD (methanol) or CD3ND2 (methylamine).
To this aim, thin films of intimate H2O:XD ice mixtures, condensed at low temperature (≤110K), have been monitored by Fourier transform infrared (FTIR) spectroscopy up to thecomplete evaporation of XD molecules. Rapid hydrogen/deuterium (H/D) exchange has
been observed, at 120K and above, through the growth of the νOD stretching mode of
HDO at 2425 cm-1. It has been also shown that H/D exchange occurs (i) on the hydroxyl
and amino functional groups of XD molecules, i.e. through hydrogen bonds, and (ii)before the completion of crystallization. The present results suggest therefore that themuch lower abundance of CH3OD compared to CH2DOH in low-mass protostars could
simply reflect H/D exchanges in water ice either prior to or during the grain mantle
sublimation [3]. This hypothesis will be further discussed in view of new millimeter
observations of singly deuterated methanol towards high- and intermediate-mass
protostars. Finally, new experimental data including the kinetics of H/D exchanges will
be presented and the physical processes expected to promote or limit these exchanges inspace will be emphasized.
References[1] C. Ceccarelli et al. in Protostars and Planets V, B. Reipurth, D. Jewitt, and K. Keil(eds.), University of Arizona Press, Tucson, p.47-62 (2007),[2] B. Parise et al., Astronomy & Astrophysics, 453, 949-958 (2006)[3] A. Ratajczak et al., Astronomy & Astrophysics, 496, L21-L24 (2009)

ALMA for Interstellar Matter
M. Saito,1 K. Saigo,1 K. Tachihara,1 and S. K. Okumura 1
1

East Asian ALMA Regional Center, National Astronomical Observatory of Japan, Japan

Atacama Large Millimeter-submillimeter Array (ALMA)[1] will start early scienceobservation in 2011 and provide unprecedented power to address various issues oninterstellar matter. The sensitivity of ALMA in spectral observations covering frequency
ranges of 30-900 GHz (Fig. 1) is typically 10-30 times higher than that of the existing
millimeter and submillimeter arrays. Its high spatial and spectral resolution will enable us
to image detailed features of ISM and to reveal kinematics of ISM. Its high sensitivity
enable us to detect very weak emission such as new molecular transitions toward star
forming regions, protoplanetary disks, plenetary nebulae, Galactic center and even galaxies.
These ALMA data can be compared directly with theoretical studies enriching ourunderstanding of the interstellar physics. ALMA can also diagnose molecular abundance,
temperature, density and kinematics of many species with high precision.
The East-Asian ALMA Regional Center (EA-ARC) will provide user support in many
aspects. We present the latest status and information for the observing proposal of ALMA.

Figure 1: Left) Current frequency coverage of ALMA. Right) Atmospheric transmission in the ALMA
frequency coverage given precipitable water vapor in atmosphere.

References[1]

S. Iguchi et al. 2009, PASJ, 61, 1

Recent Progress of Carbon-Chain Chemistry in Molecular Clouds
N. Sakai1 and S. Yamamoto1
1

Department of Physics and the Research Center for the Early Universe, The University of Tokyo, Japan

In this talk, we will present two recent progresses of observational carbon-chain chemistryin molecular clouds. One is the understanding of formation processes of carbon-chain
molecules. So far, the abundance ratio of the 13C species relative to the normal species isassumed to be the same as the elemental abundance ratio of 12C/13C (60). However, we haverecently observed the 13C species of CCS, and have found the CCS/C13CS and CCS/13CCS
ratios are 54±5(3σ) and 230±130(3σ), respectively, in TMC-1. The abundance ratio of
C13CS/13CCS is not unity and 13CCS is heavily diluted. This indicates that the two carbon
atoms are nonequivalent in the main formation pathway of CCS. Although the isotope
exchange reaction between 13CCS and C13CS may be responsible in part, these results will put
strong constrains on the production pathways of CCS. For instance, non-equivalent processes
like CH + CS is turned out to be important to produce CCS [1]. Similarly, the 13C species of
CCH is observed, and the C13CH/13CCH ratios are determined to be 1.6±0.4(3σ). Again, thetwo carbon atoms are nonequivalent. Furthermore, C13CH and 13CCH are also found to besignificantly diluted [2]. The heavy dilution of the 13C species is now confirmed
observationally, which will provide us with rich information on physical and chemical
conditions of interstellar clouds.
Second is the discovery of new carbon-chain chemistry in a lukewarm region near the
protostar triggered by the evaporation of the CH4 ice. We have found low-mass star formingregions, L1527 and IRAS15398-3359, which show extremely high abundances of carbonchain molecules [e.g. 3, 4]. In particular, we have confirmed the regeneration of carbon-chain
molecules in the 20-30 K region near the protostar by interferometric observation toward
L1527. The new chemistry is named as Warm Carbon-Chain Chemistry (WCCC) in contrast
to the conventional one which has long been applied to cold starless cores. The understandingof the anion chemistry has been accelerated by the detection of C4H- and C6H- in L1527. The
discovery of the WCCC sources demonstrates that the chemical composition of low-massstar-forming regions is not uniform, but has a significant variety. A remarkable contrast canbe seen between WCCC and hot corino chemistry. A possible origin for this would be thetime scale of the starless-core phase; a shorter contraction time would result in WCCC. If so,chemical compositions tell us the past history of the star formation processes, which would
not be derived from the conventional observations.
References
[1]
[2]
[3]
[4]

N. Sakai et al. 2007, ApJ, 663, 1174.
N. Sakai, O. Saruwatari, T. Sakai, S. Takano, and S. Yamamoto. 2010, A&A, 512, A31
N. Sakai, T. Sakai, T. Hirota, and S. Yamamoto. 2008, ApJ, 672, 371
N. Sakai, T. Sakai, T. Hirota, M. Burton, and S. Yamamoto, 2009, ApJ, 697, 769.

Properties of PAH emission in Nova V1280 Sco
I. Sakon,1 T. Onaka,1 T. Shimonishi,1 R. Ohsawa,1 F. Usui 2
1
Department of Astronomy,Graduate Schools of Science, University of Tokyo, Japan
2
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Japan

We have carried out the near-infrared spectroscopy of dust forming nova V1280 Sco with
Infrared Camera (IRC) onboard AKARI on 2009 Sep. 9, which corresponds to the epoch of~940 days after outburst. The obtained near-infrared spectrum have shown distinct red
continuum accompanied by 3.3µm “PAH” feature with extraordinary strong red wing in 3.4—
3.6µm (see Figure 1). While the 3.3um feature is assigned as the stretching mode of aromaticCH, the 3.4—3.6µm wing components are assigned as the stretching mode of aliphatic CH
groups. Larger 3.4/3.3 ratio in V1280 Sco may indicate the higher aliphatic-to-aromatic ratioof the carriers than the case of general interstellar PAHs. Our results are consistent with theremark of Evans & Rawling (1994) that the observed ‘PAH’ features in nova are likely to be
carried by HACs rather than free-flying PAHs. We also have carried out the follow-up midinfrared observation of this nova with TReCS onboard Gemini South telescope on 2010 Aug.
2-3 (GS-2010B-C-7), which corresponds to the epoch of ~1260 days after the outburst. In thispresentation, we will introduce the latest results of those observations and discuss the dust
formation around an interesting nova V1280 Sco.

Figure 1: (a) Near-Infrared spectrum of V1280 Sco on the epoch 940 days after the discovery normalized tothe continuum obtained with Infrared Camera (IRC) onboard AKARI. 3.3µm “PAH” feature with a strong
red-wing components in 3.4-3.6µm was recognized in the obtained near spectrum (Sakon et al. 2010, in
preparation). (b) An example of near-infrared spectrum of Galactic diffuse ISM obtained with AKARI/IRC
for a comparison.
.

References[1][2]

A. Evans, & J.M.C. Rawlings, 1994, MNRAS, 269, 427
I. Sakon, et al. 2010, in prep.

Infrared Observations of Ices around Young Stellar Objects in the Smalland Large Magellanic Cloud
Takashi Shimonishi1, Takashi Onaka1, Daisuke Kato2, Itsuki Sakon1,
Yoshifusa Ita3, Akiko Kawamura4 and Hidehiro Kaneda4
1

Department of Astronomy, Graduate School of Science, University of Tokyo, Japan
2
ISAS/JAXA, Japan
3
Astronomical Institute, Tohoku University, Japan
4
Graduate School of Science, Nagoya University

Question of where molecules like water or carbon dioxide on the Earth's surface came from is
one of the main topics of the current “astrochemistry”. One of the possible origins of thesemolecules is the "ices" around young stellar objects (YSOs). Observations of ices aroundextragalactic YSOs are one of the challenging topics in the recent ice studies. So far, infrared
spectroscopic observations toward extragalactic embedded YSOs are few, and theircircumstellar chemistry is still poorly understood. But it is highly probable that different
galactic environments (e.g., metallicity, radiation field, etc.) could affect the properties ofcircumstellar material.
In this study, we first focused on YSOs in the Large Magellanic Cloud (LMC), which is thenearest metal-poor galaxy to our Galaxy. We investigated the chemical conditions of icesaround high-mass YSOs in the LMC by near-infrared (2—5 micron) spectroscopic
observations with the infrared satellite AKARI [1, 2]. As a result, we detected the absorption
features of 3.05 micron H2O ice, 4.27 micron CO2 ice, and 4.67 micron CO ice toward these
extragalactic YSOs. We derived column densities of these ices and showed that YSOs in the
LMC have higher abundance of CO2 ice than similar Galactic counterparts. In addition, weinvestigated the correlation between the chemical abundance of ices and properties of each
YSO. Next, we also performed the spectroscopic observations of YSOs in the Small
Magellanic Cloud, whose metallicity is much lower than the LMC, and detected theabsorption features of the above major ice species [3]. .
In this study, we present the latest results of our spectroscopic observations toward
extragalactic YSOs, and discuss how the chemical properties of ices depend on the galactic
metallicity and YSO properties.
References[1] T. Shimonishi, et al., ApJ, 686, L99, (2008)[2] T. Shimonishi, et al., A & A, 514, A12, (2010)[3] T. Shimonishi, et al., in prep.

Properties of dust around Eta Carinae during the periastron event in 2009 based onnear infrared multi-epoch photometric observations with the Wide Field Cryogenic
Telescope 2 (WFCT 2)
Janette Suherli1, Itsuki Sakon2, Takashi Onaka2, Ryou Ohsawa2, Daisuke Kato3, Kentaro
Haraguchi4, Mikio Kurita4
1

Astronomy Study Program/Bandung Institute of Technology, Indonesia
Department of Astronomy Graduate School of Sciences/University of Tokyo, Japan
3
Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency, Japan
4
Department of Astrophysics/Nagoya University, Japan
2

Eta Carinae is known as one of the most massive binary system in a relatively old stage in its
evolution. It has shown drastic variations in brightness, at least, during past few centuries. In
recent several decades, it is known that this star has a periodic variation in brightness atvarious wavelengths occurring every 5.54 years, which corresponds to the orbital phase of thebinary system, and it is termed as "spectroscopic event". Most believed that during this event
dust is formed around Eta Carinae due to the wind-wind collision. The near-infraredobservation was carried out during the 2009 spectroscopic event with the WFCT 2 in South
Africa, which covered a period before and after the spectroscopic event. In this report we
present the data from 10 to 29 January 2009. The light curve that we obtained from the datashows a steep decline in this period. Our interest is the properties of the dust grain around Eta
Carinae in such a small time span near the spectroscopic event. Monitoring of the variation innear-infrared light curve is quite efficient to investigate the properties of the hot dust. The
result shows that the dust temperature increases while the dust mass decreases. Our data leadto that there is some destruction of dust in a few weeks around the spectroscopic event.

Separation and conversion dynamics of nuclear spin isomers of gaseous molecules
Z.-D. Sun,1,2 Y. Moriwaki,2 and F. Matsushima 2
1

2

School of Physics, Shandong University, China
Department of Physics, University of Toyama, Japan

Matter is composed of molecules and all molecules possessing identical nuclei with nonzero
spin, in accordance with Pauli’s principle, have distinct nuclear spin isomers [1]. Can one of
nuclear spin isomers of the gaseous molecules be separated from others? Is it possible that
nuclear spin conversions among the nuclear spin isomers occur and can be observed
spectrospically? How long can these isomers exist in real time? Addressing these question
leads to interesting scientific explorations. In astronomy and astrophysics, it is widelyassumed that the conversion probabilities among nuclear spin isomers for the various
molecules in the interstellar matter are zero, even over time spans of millions of years [1].
However, this assumption is quite questionable. The observed values obtained in our study
are good tests for the validity of this assumption.
We are performing researches on separation of nuclear spin isomers of gaseous interstellar
molecules by the most reliable and powerful light-induced-drift technique [1-3] and on theconversion observations of these enriched spin isomers in long time relaxation processes via
precision measurements of the spectral line intensities. Our experimental results and detailed
physical explanations of the nuclear spin conversion mechanisms will be reported in theWorkshop on Interstellar Matter 2010.

References
[1]
[2]
[3]

Z.-D. Sun, K. Takagi, & F. Matsushima, 2005, Science 310, 1938.
J. T. Hougen & T. Oka, 2005, Science 310, 1913.
P. L. Chapovsky, 1990, JETP 70, 895.

Nobeyama 45 m telescope legacy project: Line survey (II)Takano, S. (NRO), Aikawa, Y. (Kobe U.), Chen, V. (NTHU), Hirano, N. (ASIAA), Hirota, T. (NAOJ),
Kamegai, K. (JAXA), Kobayashi K. (Toyama U.), Kohno, K. (U. Tokyo), Kuan, Y-J. (NTNU), Liu, S.-Y.
(ASIAA), Nakajima, T. (NRO), Ohashi, N. (ASIAA), Ohishi, M. (NAOJ), Ozeki, H. (Toho U.), Sakai, N.
(U. Tokyo), Sakai, T. (U. Tokyo), Shiba, S. (U. Tokyo), Su, Y.-N. (ASIAA), Sugimura, M. (U. Tokyo),
Takahashi, S. (ASIAA), Takakuwa, S. (ASIAA), Umemoto, T. (NAOJ), Wang, K.-S. (ASIAA), Yamada,
M. (ASIAA), Yamamoto, S. (U. Tokyo), Zhang, Q.-Z. (CfA)

Line surveys are of fundamental importance in astronomy not only for complete
understanding of chemical compositions in representative sources, but also for finding out
new observing tools probing interstellar medium and star formation. We started the line
surveys toward a few new types of sources with the Nobeyama 45 m telescope in December
2007. The target sources include the low-mass star forming region L1527, the shocked regionof L1157, infrared dark clouds G28.34+0.06, and external galaxies Arp 220, NGC 1068 andNGC 253. Mainly with the new 3 mm receivers installed on the 45 m telescope [1], thefrequency range of ~84-115 GHz will be surveyed with much higher sensitivity than theprevious observations. The total observing time is expected to be about 1000 hours for four
years. The results from the survey will be used for detailed studies on chemistry in eachsource, and will also provide us with useful templates for planning the observing strategy with
ALMA. The third year of the line surveys was finished. We report the preliminary results.
L1527 is a very interesting object, because the abundances of carbon-chain molecules are
high, though this source is a low-mass star-forming region [2]. We detected many lines
including high excitation lines of HC5N (e.g. J=41-40, upper state energy of 110 K), isotopic
species (D, 13C) of some carbon-chain molecules, HCO, C3O, cyclic-C3H, etc. These data
will be quite useful to understand chemistry in this warm environment.
In L1157, where interactions between an outflow and ambient clouds are prominent [3, 4], we
detected many lines including C2H, C34S, CCS, HCNO, CH3CN, CH3CHO, HCOOCH3, andNH2CHO. To study shock chemistry and gas-grain interaction, these results are rather
important information. After our observations, we noticed that HCOOCH3 is independently
detected with the IRAM 30 m telescope [5].
In G28.34+0.06 three interesting positions called mm1, mm4, and mm9 are selected. Toward
mm1 and mm4 line wings were found in HCO+, HCN, SiO, CS, and CH3OH. These wings
indicate outflow activities. In addition, CH3CHO is detected only in mm1 and mm4. This
molecule is one of the probable grain related species. Therefore CH3CHO may be evaporated
from grain. Based on these results, mm1 and mm4 are thought to be high-mass protostellar
objects. Additional data supporting this view were obtained from DNC, DCO+, and N2D+.
About galaxies we are mainly observing NGC 1068, which is a nearby galaxy with Active
Galactic Nucleus (AGN). Our motivation is to study the effect of AGN on molecularabundances (cf. [6]). In addition a prototypical starburst galaxy NGC 253 is observed forcomparison. We detected C2H (N=1-0), H13CN (J=1-0), and cyclic-C3H2 for the first time in
NGC 1068. The details will be presented in this workshop by Nakajima et al.
References [1] Nakajima et al. 2008, PASJ 60, 435. [2] Sakai et al. 2008, ApJ 672, 371. [3] Umemoto et al.
1992, ApJ 392, L83. [4] Mikami et al. 1992, ApJ 392, L87. [5] Arce et al. 2008, ApJ 681, L21. [6] Kohno et al.
2008, Ap&SS 313, 279.

Laboratory measurements of atomic hydrogen diffusion and the ortho-para conversionof nascent H2 molecules on amorphous solid water
N. Watanabe1, T. Hama1, A. Kouchi1, T. Chigai1, V. Pirronello 2, Y. Kimura3
1

Institute of Low Temperature Science, Hokkaido University, JAPANDipartimento di Metodologie Fisiche e Chimiche, Università di Catania, ITALY
3
Department of Earth and Planetary Materials Science, Tohoku University, JAPAN2

We experimentally approach the two astronomically significant issues: diffusion of hydrogen
atom on amorphous solid water (ASW) at a low temperature and the ortho/para ratio ofnascent H2 molecule formed by recombination on ASW. Atomic hydrogen on ASW was
directly detected by the combination of a photostimulated desorption and a resonanceenhanced multiphoton ionization techniques [1]. Using this method, attenuation in the numberof hydrogen atoms on ASW due to recombination and/or desorption was first measured intemperature range 8—20 K at very low H atom coverage, relevant to H2 formation on cosmic
ice dust. The obtained attenuation curve at 8 K clearly consists of fast and very slow
components. The fast component is mainly attributable to the loss by H-H recombination after
H-atom diffusion on shallow potential sites, while the very slow component would reflect thehydrogen atoms trapped in deep potential sites of ASW. Activation energies of the H-atom
diffusion on shallow and deep potential sites are determined to be ~20 and >50 meV,
respectively. Our results cover the previously reported activation energies of both 22 [2] and41-55 meV [3]. The ortho-para nuclear spin ratio of nascent H2 formed by recombination on
ASW has been obtained for the first time and is higher than approximately 200 K. Afterformation, H2 molecules are trapped and their spin temperature decreases due to theconversion of spin states on ASW. The scenario for H2 formation on cosmic ice dust is thatthe hydrogen atom encounters another atom strongly trapped in the deep site after traveling on
the shallower potential sites and after formation, H2 molecules are trapped and their spintemperature decreases due to the conversion of spin states on ASW.

References[1] N. Watanabe et al. 2010, ApJL, 714, L233
[2] E. Matar et al. 2008, A&A, 492, L17.
[3] H. B. Perets et al. 2005, ApJ, 627, 850.

Line survey of RCrA IRAS7B in the 345GHz window with ASTE
Y. Watanabe 1 , N. Sakai 1, S. Yamamoto 1, J. Lindberg 2 , J. Jørgensen 2, S. Bisschop 2
1

Department of Physics, the University of Tokyo, Japan
2
University of Copenhagen, Denmark

Recently it is established that chemical compositions of low mass star forming regions
harboring the Class 0 protostar are different from source to source ([1], [2], [3] etc.). One
extreme case is a hot corino, where various complex organic molecules like HCOOCH3 areabundant. These complex molecules may be related to the pre-solar material found inmeteorites. Therefore it is very important to characterize the chemical compositions of the
hot corinos and its variation in detail. However, a line survey toward a hot corino source iscarried out only toward IRAS 16293-2422, and it has not been published yet.
With these in mind, we have conducted a sensitive line survey in the 345 GHz band
toward RCrA IRS7B with the ASTE 10 m telescope. RCrA IRS7B is a class 0 object inCorona Australis with the distance of about 170 pc [4]. Schoier et al. [5] detected the highexcitation lines of H2CO and CH3OH toward this source, indicating that it is a good candidateof the hot corino source.
The RCrA IRS7B has been surveyed from 332 GHz to 352 GHz with frequency
resolution of 0.5 MHz. The typical R.M.S. noise level is 10-15 mK in TA*. From thesurvey, we have identified 15 fundamental molecular species and 11 isotopomers. On theother hand, complex organic molecules, which consists of more than 4 heavy atoms, have notbeen detected definitively. In our poster, we will present the current results of our survey(fig.1 a) and discuss physical conditions of molecular gas (fig.1 b) and deuterium
fractionation ratio in the source. This is a collaborative study with the University of
Copenhagen group, which is conducting the line survey in the 230 GHz band toward the same
source with APEX.


Figure 1: (a) A portion of obtained spectra from 348GHz to 352 GHz. (b) n example of therotation-diagram analysis for c-C3H2. The estimated excitation temperature (Trot) and column density (N)are 16.2 ± 1.2 K and (4.0 ± 1.3) x 1012 cm-2, respectively.
References[1]
Schoier et al. 2002., A&A, 390, 1001
[2]
Cazaux et al. 2003., ApJ, 593, L51[3]
Sakai et al. 2008., ApJ, 672, 371[4]Kunde & Høg 1988., A&A, 338, 897[5]
Schoier et al. 2006, 454, L67

Translational and rotational energy measurements of vacuum-ultraviolet photodesorped
water molecules in their vibrational ground state from amorphous solid water
A. Yabushita,1 T. Hama,2 M. Yokoyama,1 M. Kawasaki,3 S. Andersson,4 C. M. Western,5M. N. R. Ashfold,5 R. N. Dixon,5 and N. Watanabe2
1

Department of Molecular Engineering, Kyoto University, Japan
Institute of Low Temperature Science, Hokkaido University, Japan
3
Research Institute for Humanity and Nature, Japan
4
SINTEF Materials and Chemistry, Norway and Department of Chemistry, Physical
Chemistry, University of Gothenburg, Sweden
5
School of Chemistry, University of Bristol, United Kingdom
2

For large grains in the cosmic space, the most important desorption mechanism at the edge ofmolecular clouds is photodesorption. To reveal the details of photodesorption mechanism, we
have experimentally measured the average translational and rotational energies forphotodesorbed H2O (v=0) from amorphous solid water (ASW) and polycrystalline ice (PCI) at
90 K using 157 nm laser. The experimental findings are compared with the results of classicalmolecular dynamics (MD) calculations performed for photodesorption from ASW.
The rotational temperature Trot(v=0) is estimated to be 300 ± 100 K by spectral simulation.
Time-of-flight spectrum of H2O (v=0) measured for the (202-321) line of the REMPI spectrum
was measured, which is well reproduced by a M-B distribution with Ttrans(v=0) = 1800±500 K.
The main mechanisms for this photodesorption is a “kick-out” of an H2O molecule on the ice
surface by the energetic H atom released from photodissociation of H2O + hν → H + OH.(Fig.
1) The experimentally observed average translational and rotational energies are in goodaccord with predictions by classical molecular dynamics calculations for the “kick-out”
mechanism. H2O molecules desorbed from ASW might be expected to lose energy ininteractions with cold ice surface. Hence, a slow TOF component might be expected. The
absence of any such slow TOF component suggests that H2O only on the ice surface candesorb and not from bulk phase.

Figure 1 Schematic illustrations of a “kick-out” of another H2O molecule in the ice by the energetic H atom
released from VUV irradiation of amorphous water ice. The numbers dedicate for sequence of the reaction.

References[1] A. Yabushita, T. Hama, M. Yokoyama, M. Kawasaki, S. Andersson, C. M. Western, M. N. R. Ashfold, R.
N. Dixon, & N. Watanabe, 2009, ApJ 699, L80.
[2] T. Hama, M. Yokoyama, A. Yabushita, M. Kawasaki, S. Andersson, R. N. Dixon, M. N. R. Ashfold, & N.
Watanabe, 2010, J. Chem. Phys. 132, 164508.

THz high-resolution TuFIR spectroscopy ofpure rotational transitions of molecular ions H2D+
T. Yonezu 1
1

Nobeyama Radio Observatory/National Astronomical Observatory of Japan

Light molecules or ions composed of small number of light atoms such as hydrogen play key
roles in the history of chemical evolution of interstellar species. Precise frequency
measurement of rotational lines of such light species is important to improve rotational
constants of the species and to give precise prediction of the rotational lines for future searchof the species.
So far, we have investigated rotational lines of molecules and ions in the far-infrared region(in the range from 0.8 to more than 5 THz) by using tunable far-infrared spectrometer(TuFIR) at University of Toyama. The spectrometer is based on the difference frequency
generation from the selectable stabilized two CO2 laser lines. And He-liquid cooled Sicomposite bolometer.
Fig.1 shows the 212 - 111 line of H2D+ observed at 2.363 THz with TuFIR spectrometer. Thisline was previously detected toward Sgr B2 by Cernicharo et al [1]. Four lines of H2D+ wereobserved with our spectrometer.

Figure 1: J = 212←111 transition of H2D+.

Figure 2: J = 14←13 transition of N2H+.

As for the lower frequency data, Asvany et al. [2] observed the 101 - 000 line (1370085.3
MHz) by using laser induced chemical reaction detection method. Our observed THz lines(211-110, 313-212, 202-101, 212-111) recorded in the shape of first derivative curve were analysed
together with known millimeter- and sub-millimeter-wave lines, and the combinationdifferences derived from the infrared lines to obtain the parameters in Watson’s effective
Hamiltonian. A set of improved molecular constants are obtained [3].
The spectrometer is now modified to introduce a discharge sample cell using extended
negative glow discharge technique. Fig.2 shows the test data of N2H+ observed by using theextended negative glow discharge. The spectral line was enhanced by one order of magnitude
by using the new discharge cell.

References[1]
J. Cernicharo, E. Polehampton, J.R. Goicoechea, 2007, Astrophys. J. 657, L21-L24.
[2]
O. Asvany, O. Ricken, H.S.P. Muller, M.C. Wiedner, T.F. Giesen, S. Schlemmer, 2008, Phys. Rev. Lett.
100, 233004.
[3]
T. Yonezu, F. Matsushima, Y. Moriwaki, K. Takagi, T. Amano, 2009 J. Mol. Spectrosc. 256, 238-241.