Ⅲ-3
Chemistry

601_Ⅲ_BL3U_9002_長坂

Ⅲ -3. Chemistry

将成

BL3U

Surface-Dependent Hydration of Nanodiamonds in Colloidal Dispersions
T. Petit,1 H. Yuzawa,2 M. Nagasaka,2 H. Girard,3 J.-C. Arnault,3 O. Shenderova,4 N. Kosugi2and E. F. Aziz1,2,5
1Institute of Methods for Materials Development, Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489
Berlin, Germany
2
Institute for Molecular Science, Okazaki 444-8585, Japan
3
CEA, LIST, Diamond Sensors Laboratory, F-91191 Gif-sur-Yvette, France
4
Adamas Nanotechnologies Inc., 8100 Brownleigh Dr., Raleigh, North Carolina 27617, USA
5
Freie Universität Berlin, FB Physik, Arnimallee 14, 14195 Berlin, Germany

The organization of water molecules close to solid
surfaces or around proteins differs significantly frompure water [1]. Reorganization of solvent molecules islikely to occur around colloidal nanoparticles and its
understanding is of outermost importance to better
estimate their reactivity and interaction with biologicalmoieties in aqueous environment. Nanodiamonds(NDs) are of particular interest for the investigation ofinterfacial water since the existence of an orderedwater shell ranging from 2 to 4 water layers wasrecently suggested. In 2014, we have observed that Xray Absorption Spectroscopy (XAS) in puretransmission was particularly efficient to probe waterinterfacial water around NDs [2].
During this beam time at UVSOR-III, aqueous
dispersions of NDs with different surface chemistries
prepared from the same initial ND produced bydetonation synthesis (diameter ~5nm) by Adamas
Nanotechnologies were compared. Carboxylated(NDs-COOH),
hydroxylated(NDs-OH)andhydrogenated (NDs-H) were characterized. For
comparison, NDs produced by High Pressure High
Temperature (NDs-HPHT), with a diameter of 16 nm,
were also characterized. By comparing these XA
spectra at oxygen K edge to pure water spectra (Fig. 1),
the organization of water molecules in hydration layersof NDs could be investigated.
After normalization to the absorption intensity
before and after the oxygen edge, strong intensity
variations of the signal were observed, which can beinterpreted by surface-dependent variation of the water
arrangement around NDs. NDs-OH are positivelycharged, like NDs-H and NDs-sp2, but its XA
spectrum does not differ from negatively-charged
NDs-COOH. This result demonstrates that the water
structure is not dependent on the Zeta potential of NDs
as previously thought. The strong intensity of the mainedge intensity at 538 eV for NDs-H dispersion,
although its concentration is half of the other samples,
demonstrate that the water organization is extremely
different on hydrogenated surface. An enhancement of
this feature was previously observed on surfacegraphitized NDs (NDs-sp2), also having hydrogenatedsurface groups.
During this beam time, we could extend thepreliminary results obtained in 2014 to NDs with welldefined surface chemistries. This work demonstrates

that hydrogenated surface functional groups are thesource of particular water arrangement on NDs. These
results will be submitted for publication in the coming
months, along with complementary infrared andRaman spectroscopies results.

Ⅲ-3

Fig. 1. (a) XAS of oxygen K-edge from water andaqueous dispersion of detonation NDs with different
surface chemistries. Concentration is 1 wt % except for
NDs-H (0.5 wt %). Surface-graphitized NDs (NDssp2) spectrum is extracted from reference 2.
[1] J.-J. Velasco-Velez et al., Science 346 (2014) 831.
[2] T. Petit et al., J. Phys. Chem. Lett. 6 (2015) 2909.

93531_Ⅲ_BL1U_211_秋津貴城.docx
Ⅲ -3. Chemistry

BL1U

Induced Chirality by Circularly Polarized UV Light for Photofunctional
Organic/Inorganic Hybrid Materials: Tuning Electrochemical Properties ofArtificial Metalloproteins
T. Akitsu1, M. Sunaga1, M. Takase1, T. Konomi2 and M. Katoh2

Department of Chemistry, Faculty of Science, Tokyo University of Science, Tokyo 162-8601, Japan
2
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan1

Ⅲ-3

In 2015, we have studied on linearly or circularly
polarized UV light induced molecular orientation ofchiral metal complexes in polymer matrix (synthetic
polymers or proteins) and controlled electronic
properties of the metal complexes as organic/inorganic
hybrid materials. The advantage of using UVSOR
facility (BL1U) is to generate wavelength-selective
and polarized UV light with high intensity.
We have prepared supramolecular chiral systems as
artificial metalloproteins composed of several chiralsalen-type Mn(II) and Co(II) complexes in a humanserum albumin (HSA) matrix. After linearly polarized
UV light irradiation, that anisotropy of molecularorientation of the complexes increased was confirmedby polarized IR spectra. We have observed that theelectrochemical behavior of the aligned complexes
incorporating diphenyl groups in HSA can be tuned
without UV radiation damage of HSA higher structures.
As shown in Fig. 1, we have simulated several
organic/inorganic hybrid materials structurally, inother words, artificial metalloproteins composed ofchiral salen-type Mn(II) or Co(II) complexes and HSA
proteins. We also measured polarized UV-vis spectraor IR spectra after linearly polarized light UV light or
CD spectra after circularly polarized light UV light toconfirm induced molecular orientation due to Weigert
effect. Weigert effect by linearly polarized UV lightcauses dichroism due to anisotropic aligned metal
complexes in a HSA matrix with photochemical
reactions as well as interaction with highly polar
molecules.
In addition, even strong synchrotron UV linearlypolarized UV light irradiation (at 260, 318, and 380 nm
of 102 mm2 spot at 10 mW/cm2 generated with an
undulator at IMS UVSOR BL1U [1]) did not damaged
higher structure of HSA for the artificial
metalloproteins. Little changes from the initial CD
spectra in the range of 200-900 nm could be observed
after 1, 3, and 5 min irradiation.
As depicted in Fig. 2, the CV measurements
revealed the effects of UV light for not only metal
complexes but also the artificial metalloproteins.
Relatively UV light-resistant metal complexes
exhibited CV changes after UV irradiation for 10 min,which may be in agreement with expectation based on
the intra-ligand transitions or stable isolation and O2oxidation during preparation from Mn(II) source forthe analogous Mn(III) complexes. As for diphenyl
incorporating metal complexes-HSA hybrids, little CVchanges could be observed significant CV changes(decreasing current) only after 1 min polarized UV
irradiation.

Fig. 1. Docking simulation (GOLD) of a chiral metal
complex into HSA protein.

Fig. 2. Changes of CV of an artificial metalloprotein
after polarized UV light irradiation.
[1] UVSOR, UVSOR Activity Report 41 (2014).

94541_Ⅲ_BL1U_607_金安達夫.docx

Ⅲ -3. Chemistry

BL1U

Photoionization of Helium Atoms by Photon Beams Carrying Orbital
Angular Momentum
T. Kaneyasu1, Y. Hikosaka2, M. Katoh3, H. Iwayama3 and E. Shigemasa3

1
SAGA Light Source, Tosu 841-0005, Japan
Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
3
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan

2

Light beam characterized by helical wavefront andannular intensity distribution carries orbital angularmomentum (OAM). Since the pioneering work by
Allen et al. [1], the OAM photons have been attracting
interests in a variety of research fields such as quantum
information, manipulation of micro particles and highresolution microscope. Until now application of the
OAM photons has been limited to the visible andinfrared wavelength region because it is generally
difficult to produce helical wavefront at shortwavelengths using optical elements.
Recently it was found that the nth harmonic
radiation from a helical undulator carries OAM of (n1)ħ per photon [2,3]. This accelerator-based method
directly and efficiently produce circularly polarized
OAM photon beams in a wavelength range coveringfrom VUV to hard X-rays. Following the successful
generation of the OAM photon beam in the UVSOR
storage ring, we started an experimental study [4] on
the interaction of the OAM photon with gas-phaseatoms in which violation of the dipole selection rule ispredicted [5].
The experiments were performed at the beamline
BL1U using the OAM photon beam produced as the
harmonic radiation from the APPLE-II undulator.
The undulator radiation was collimated by ϕ1 mm
pinhole and transported into the experimental chamber
without optical elements. We measured angular
distributions of He 1s photoelectron using the imaging
method. Although we had experimental problems
regarding the photon beam alignment and backgroundsubtraction in the image data, some preliminary results
are presented in this report.
The left panels in Fig. 1 show the He 1s
photoelectron images measured for the circularly
polarized fundamental, second and third harmonic
radiation, corresponding to the photon beams carrying
OAM of 0ħ, 1ħ and 2ħ per photon, respectively. The
peak photon energy of the undulator radiation was
roughly set to 30 eV for each harmonic. The rightpanels in Fig. 1 show the angular distributions of thephotoelectrons converted from the projected images
using the peeling-analysis. The measured angular
distributions are in reasonable agreement with those
calculated for the dipole asymmetry parameter β = 2even for the l = 1 and 2 cases. This result implies thatthe dipole transition dominates the OAM photon-atominteraction under the present experimental condition
where the He atoms are uniformly distributed among

the photon beam of 1 mm diameter. For confirming thepresent observation, we plan to perform thephotoionization experiment after the beamline
construction scheduled in 2016.

Ⅲ-3

Fig. 1. Left: Images of He 1s photoelectrons. Right:
Photoelectron angular distributions converted from theimages. Solid curves represent the calculation for β=2.
The photoelectron images were measured for thecircularly polarized photon beams carrying OAM of lħ(l=0-2) per photon.
[1] L. Allen et al., Phys. Rev. A 45 (1992) 8185.
[2] S. Sasaki and I. McNulty, Phys. Rev. Lett. 100(2008) 124801.
[3] J. Bahrdt et al., Phys. Rev. Lett. 111 (2013) 034801.
[4] T. Kaneyasu et al., UVSOR Activity Report 42(2014) 110.
[5] A. Picón et al., New J. Phys. 12 (2010) 083053.

95

551_Ⅲ_BL3U_9000_小杉信博.docx
Ⅲ -3. Chemistry

BL3U

Local Structure Observation of Aqueous KSCN Solution by Soft X-Ray
Absorption Spectroscopy. Part I. O K-Edge XAS for Solvent Water.
H. Yuzawa, M. Nagasaka and N. Kosugi

Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan

4

Absorption Coefficient / 10 cm-1

O K-edge XAS spectra for water can give theinformation about tendency of the breaking ofhydrogen bond network and that of the formation of
hydration structure between K+ and H2O.
4 (a)
3
2
1
0
(b)

(KSCN)x(H2O)1-x

1.0

530

x = 0.3
x = 0.25
x = 0.2
x = 0.15
x = 0.1
x = 0.05
x = 0.025
x = 0.0125
x = 0.005
x = 0.002
x = 0 (Pure H2O)

535
540
545
Photon Energy / eV

4

0.08

(a)
1.0

(b)

0.06
Energy Shift / eV

-1Fig. 1. O K-edge XAS of (KSCN)x(H2O)1-x solutions
in various ratios from x = 0 to 0.3.
Absorption Coefficient / 10 cm

Ⅲ-3

Aqueous solution of highly concentrated electrolyte
has been studied extensively, where cations and anionsin water were not completely hydrated and interact
with each other to produce complicate aggregatedstructures [1]. However, since it is difficult to clarify
their structures by a few kinds of spectroscopic
observation, more accumulation of spectroscopic
insights is required.
Our research group has developed a new liquid cellfor the soft X-ray XAS in transmission mode and has
applied it to O K-edge XAS measurements of someelectrolyte solutions. As a result, we have clarified thehydration structure around the cation [2]. In the present
study, we have extended the measurement to bothwater and electrolyte in aqueous KSCN solutions, andhave investigated the concentration dependence from
dilute to nearly saturated one. In this part, we report theO K-edge XAS of water in the solutions.
The experiments were carried out at BL3U. First,
the (KSCN)x(H2O)1-x solution samples (x values arefrom 0 to 0.3. x = 0.3 corresponds to 9.1 M.) wereprepared and flowed into the liquid cell which iscomposed of two Si3N4 membranes. Then, thethickness of liquid cell was optimized by controllingthe He pressure around the cell and the O K-edge XAS
measurement was started. The photon energy wascalibrated by the oxygen 1s → π* excitation peak
(530.8 eV) of O2 gas mixture in He.
Figure 1 shows O K-edge XAS spectra of the(KSCN)x(H2O)1-x samples. In the Fig. 1a, theabsorption intensity of the post-edge region around
540 eV decreases with increasing the KSCN
concentration. Since this region is assigned to multiple
scattering in the hydrogen bond network of water [3],this tendency suggests that the more hydrogen bond isbroken by KSCN in higher concentration. In the Fig.
1b, the sharp absorption peak at the main-edge region
around 537 eV is clearly observed for highconcentration range from x = 0.2 to 0.3, whose changeof absorption comes close to the spectrum of water
vapor [4]. Thus, this peak would be derived from theexistence of isolated water molecule (or cluster)
surrounded by KSCN.
Figure 2a shows magnified figure of the pre-edge
peaks around 534.5 eV in Fig. 1. Figure 2b shows thepeak energy shift values of these peak tops. The blue
shift of the peak top is larger with increasing theconcentration. This indicates that the hydration
structure between H2O and K+ (K+ − OH2 interaction)
increases in number, as reported previously [2].
Therefore, the KSCN concentration dependence of

0.04
0.02

y = 0.20x + 0.013

0
-0.02
534.0
535.0
Photon Energy / eV

(KSCN)x(H2O)1-x

0
0.1
0.2
0.3
Molar Fraction of KSCN (X)

Fig. 2. (a) Magnified figure of the pre-edge region in
the O K-edge XAS spectra of the (KSCN)x(H2O)1-x
solutions shown in Fig. 1. (b) The energy shifts of thepre-edge peak top.
[1] Y. Marcus, Chem. Rev. 109 (2009) 1346.
[2] M. Nagasaka, H. Yuzawa and N. Kosugi, J.
Spectrosc. Relat. Phenom. 200 (2015) 293.
[3] Ph. Wernet et al., Science 304 (2004) 995.
[4] T. Tokushima et al., Phys. Chem. Chem. Phys. 16(2014) 10753.

96Ⅲ -3. Chemistry

561_Ⅲ_BL3U_9000_小杉信博.docx

BL3U

Local Structure Observation of Aqueous KSCN Solution by Soft X-Ray
Absorption Spectroscopy. Part II. C and N K- Edge and K L-Edge XAS for
Solute KSCN.
H. Yuzawa, M. Nagasaka and N. Kosugi

Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
Oxygen K-edge XAS spectra of water in(KSCN)x(H2O)1-x (x = 0 − 0.3) solutions have revealed
that the increase of KSCN induces the breaking ofhydrogen bond in water and increases the number ofhydration structure (K+ − OH2 interaction) [1]. In thispart, we report XAS measurements for the solute
KSCN (K L-edge, C K-edge and N K-edge) toinvestigate the interaction around KSCN.
The experiments were carried out at BL3U. The
procedure of the XAS measurements for the solution
samples is the same as in Part I [1]. In N K-edge XAS,
another liquid cell composed of two SiC membranes
was used. The photon energy was calibrated by theCH4 1s−3pt2 Rydberg peak (297.99 eV) of CH4 gas
mixture in He or N2 1s → π* excitation peak (400.84eV) of N2 gas mixture in He. XAS spectra of KSCN
solid sample as a reference were also obtained bymeasuring drain current in a vacuum chamber.
Figure 1a shows K L-edge XAS spectra. Twoabsorption peaks are assigned to K 2p3/2 → 3d
excitation around 297 eV and K 2p1/2 → 3d excitation
around 300 eV, respectively. These peaks show red
shift with the increase of KSCN concentration. Since
this tendency means that the electronic state around K+
comes close to that of KSCN solid (Fig. 1d), thenumber of interaction between K+ and SCN- in thesolution increase in higher KSCN concentration.
Considering the results of O K-edge XAS spectra [1],it is suggested that both interactions of K+ − OH2(hydration) and K+ − SCN- (aggregation) increase in
number. This conclusion is also supported by a recent
report of MD simulation in highly concentrated KSCN
solution [2].
Figure 1b shows N K-edge XAS spectra. The
obtained peak is assigned to the N 1s → π
excitation The same tendency (red shift toward thesolid state, Fig. 1d) as in the case of K L-edge XAS is
obtained. Thus, this can be also explained that the
number of interaction between K+ and N atom in SCNincreases with higher concentration.
Figure 1c shows C K-edge XAS spectra, which is
obtained from the C 1s → π excitation. The peak top
energies of the solution samples in C K-edge XAS are
almost constant without any dependence on the KSCN
concentration (Fig. 1d). The XAS energy shift induced
by intermolecular interaction is mainly derived fromtwo factors. The red shift is occurred by the induced
dipole interaction (stabilization) between the excited
atom and surroundings, while the blue shift is occurredby the exchange interaction (repulsion) between the
excited electron to an unoccupied orbital and thevalence and core electrons of surrounding molecules.
These influences are stronger when the intermoleculardistance is smaller. Based on this discussion, the resultof C K-edge XAS suggests that the distance between
C atom in SCN- and other species is distant, that is, theinteraction around the C atom is weaker comparedwith the interaction around the other atoms.
Therefore, aggregate structure of KSCN in highly
concentrated aqueous solution is mainly formed by the
K+−SCN- interaction and the K+−NCS interaction,
which break the hydrogen bond of water.
(b) N K-edge

Intensity / arb. units

296

298

300 302 304 399
Photon Energy / eV

Intensity / arb. units(c) C K-edge

287
288
Photon Energy / eV

Energy Shift (C, N K-edge) / eV

294

(d)
0

x = 1 (Solid)
x = 0.3
x = 0.25
x = 0.2
x = 0.15
x = 0.1
x = 0.05
x = 0.025
x = 0.0125
x = 0.005
x = 0.002

400

Slope
C K-edge 0.014
N K-edge -0.13

0.2
0
-0.2

-0.1

-0.4
K L2-edge -0.81
K L3-edge -0.89-0.2(KSCN)x(H2O)1-x

-0.3
0

-0.6
-0.8

Energy Shift (K L-edge) / eV(a) K L-edge(KSCN)x(H2O)1-x

0.2 0.4 0.6 0.8
1
Molar Fraction of KSCN (X)

Fig. 1. (a) K L-edge, (b) N K-edge and (c) C K-edge
XAS spectra of (KSCN)x(H2O)1-x solutions in various
ratios from x = 0.002 to 0.3 and KSCN solid sample (x= 1). (d) The energy shifts of the obtained absorption
peaks from a to c.
[1] H. Yuzawa, M. Nagasaka and N. Kosugi, UVSOR
Activity Report in this volume.
[2] S. Kim et al., J. Chem. Phys. 141 (2014) 124510.

97

Ⅲ-3

571_Ⅲ_BL3U_9002_長坂 将成
Ⅲ -3. Chemistry

BL3U

Development of X-Ray Detecting System Combined with Photomultiplierand Phosphor for Soft X-Ray Absorption Spectroscopy of Dilute Solutions
M. Nagasaka, H. Yuzawa, T. Ohigashi, Y. Okano and N. Kosugi
Institute for Molecular Science, Okazaki 444-8585, Japan

Ⅲ-3

Soft X-ray absorption spectroscopy (XAS) is a
powerful method to study local structures of liquid. We
have developed a liquid flow cell for XAS intransmission mode, and studied the local structures ofseveral aqueous solutions [1]. In normal aqueous
solution, soft X-ray absorption is optimized to several
tens of percent by adjusting the thickness of liquid
layers. In dilute solutions, on the other hand, thickliquid samples should be prepared for XAS of solutebecause soft X-ray absorption of solute is low.
However, the absorption of solvent is also increased
due to the thick liquid samples. It is necessary to detect
low flux (105 photons/s) of transmitted soft X-rays at
the incident X-rays of 109 photons/s. Because thedetection limit of photodiode is 107 photons/s, XAS of
100 mM solution is only measured by the photodiodedetector. In this study, we have developed a X-ray
detecting system combined with photomultiplier andphosphor for XAS of solute in dilute solutions.
The experiments were performed by using achamber-type XAS measurement system at BL3U [2].
As shown in Fig. 1, the system consists of twochambers in an ultrahigh vacuum condition and inatmospheric helium condition. These chambers are
separated by a 100 nm-thick Si3N4 membranes with thewindow size of 200 × 200 μm2. The vacuum chamberis connected to the beam line. In the helium chamber,a liquid flow cell and a soft X-ray detector are installed.
In the liquid cell, the liquid layer is sandwiched
between two 100 nm-thick Si3N4 membranes, andliquid thickness is controllable from 20 nm to several
μm. For XAS of liquid samples, transmitted soft Xrays irradiate to phosphor P43 dipped on the inlet of an
optical fiber, soft X-rays are converted to visible lights[3], and visible lights are detected by a photomultiplierconnected to the outlet of the optical fiber. We haveconfirmed that soft X-rays with 103 photons/s aredetected in this system.
Figure 2 shows Fe L-edge XAS spectrum of 8.7 mM[Fe(bpy)3] solution by using the present system. The
solvent is DMSO. We have confirmed the presence of
Fe peak in XAS regardless of the dilute solutions. The
photon flux of incident and transmitted soft X-rays are
109 and 4 × 105 photons/s, respectively. The thicknessof liquid layer is estimated to be 8 μm. We havesucceeded to measure XAS of metal atoms in dilutemetal complex solutions below 10 mM. In the futureplan, we will investigate the local structures of ligand
in dilute metal complex solutions by using C and N Kedge XAS.

Fig. 1. Schematic of a chamber-type XAS
measurement system for liquid samples. Soft X-ray
transmission through the liquid sample is detected bya system combined with photomultiplier and phosphor
dipped on the inlet of the optical fiber.

Fig. 2. Fe L-edge XAS spectrum of 8.7 mM[Fe(bpy)3] solutions. The inset shows the schematicsof the Fe metal complex.
[1] M. Nagasaka et al., J. Electron Spectrosc. Relat.
Phenom. 200 (2015) 293.
[2] M. Nagasaka et al., in preparation.
[3] A. L. D. Kilcoyne et al., J. Synchrotron Rad. 10(2003) 125.

98

581_Ⅲ_BL3U_9002_長坂

Ⅲ -3. Chemistry

将成

BL3U

X-Ray Absorption Spectroscopy of Aqueous CO2: Chemical Shifts of HCO3and CO32- Ions in Water Matrix
1

M. Patanen1, M. Huttula1, H. Yuzawa2, M. Nagasaka2 and N. Kosugi2

Nano and Molecular Systems Research Unit, Faculty of Science, 90014 University of Oulu, Finland
2
Institute for Molecular Science, Okazaki 444-8585, Japan

Increased atmospheric CO2 emissions after
industrial revolution have not only drastic effects forthe atmospheric chemistry but lead to acidification of
surface water of oceans [1]. The solubility ofmolecular CO2 is governed by Henry’s law. In water,
CO2 appears in four forms: molecular CO2, carbonicacid H2CO3, bicarbonate ion HCO3-, and carbonate ion
CO32-. A total amount of dissolved aqueous CO2
species thus varies as a function of pH, since the form
which CO2 takes in water depends strongly on pH.
Oceanic CO2 species play an important role in the
global carbon cycle not only at liquid-gas interfaces atthe oceans’ surfaces, but also at liquid-solid interfaces:
e.g., carbonated solutions dissolve silicate minerals
releasing metal ions into solution [2]. The electronic
structure of the aqueous CO2 species in pure and saline
water is essential in order to model the chemical
processes they take part in.
In this work we have studied C 1s and O 1s X-ray
absorption spectra (XAS) of CO2 species as a functionof pH at UVSOR BL3U. We have used a liquid flow
cell enabling a transmission mode soft X-ray
absorption spectroscopy thanks to the thin SiNx
membranes [3]. The solutions were prepared fromwater solution of Na2CO3 (~2 M solution has a pH of
12.5) by adding different amounts of HCl (aq) in orderto achieve the desired pH. Figure 1 a) presents the
Bjerrum plot indicating with vertical grey bars themole fractions of different species present in thestudied solutions. Since the solubility of CO2 species
decreases with the lower pH, we were able to probe
only the neutral/basic solutions consisting mostly ofbicarbonate and carbonate species.
Figure 1 b) presents the water backgroundsubtracted C 1s XAS as a function of pH. It is clearlyobserved that the absorption energies get higher andbands broader, which corresponds well to the increaseof the mole fraction of HCO3- and CO2 species in thesolution with decreasing the pH value from 12.5 to 6.4(Fig. 1 a)). Therefore, the changes in XAS in terms ofenergy shifts and broadenings evidence clearly
different bonding networks for these species.
Figure 1 c) shows the corresponding O 1s XAS ofcarbonated solutions and pure water. O1s → π* peakfrom gaseous O2 is shown for energy calibration.
Below the H2O pre-edge peak we observe a clear
shoulder whose magnitude is the greater the morebasic the solution is. This tendency is identical withthat of solubility for the total amount of CO2 species,
which decreases with the lower pH.

Ⅲ-3

Fig. 1. a) Bjerrum plot showing the mole fractions of
CO2 species as a function of pH. b) C 1s XAS ofaqueous Na2CO3 solutions. Grey bars indicate themaxima of the XAS. c) O 1s XAS showing a shoulder
before the water pre-edge peak at 534.8 eV.
[1] K. Caldeira and M.E. Wickett, Nature 425 (2003)
365.
[2] A. Putnis, Science 343 (2014) 1441.
[3] M. Nagasaka, T. Hatsui, T. Horigome, Y.
Hamamura and N. Kosugi, J. Electr. Spectrosc. Rel.
Phen. 177 (2010) 130.

99

591_Ⅲ_BL3U_9002_長坂 将成
Ⅲ -3. Chemistry

BL3U

Impacts of Conformational Geometries in Fluorinated Alkanes
1

Ⅲ-3

T. Brandenburg1, 2, R. Golnak1,2, M. Nagasaka3, K. Atak1, 2, S. S. N. Lalithambika1,2,
N. Kosugi3 and E. F. Aziz1, 2, 3

Institute of Methods for Material Development, Helmholtz-Zentrum Berlin für Materialien und Energie, AlbertEinstein-Straße 15, 12489 Berlin, Germany
2
Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
3Institute for Molecular Science, Okazaki 444-8585, Japan

Research in blood substitute formulations is gaining
more attention in the scientific community in recent
years as more pharmaceutical companies start clinical
trials on different artificial blood approaches. In
general, artificial blood consists of emulsions ofdifferent liquid or protein compounds to increase
oxygen solubility and transport capabilities as well as
to decrease toxicity to biological tissue. Two of themore promising approaches center themselves aroundhemoglobin-based carriers and fluorinated microemulsions. Despite setbacks regarding clinical tests
and medicinal approval of recent formulations, anemulsion containing perfluorodecalin named Fluosol
was successfully approved by the U.S. Food and Drug
Administration in 1989 (New Drug Application
N860909).
The
main
oxygencarrierin
Fluosol,
perfluorodecalin, is part of the family of perfluorocarbons. They have a wide range of applications
ranging from tissue oxygenation to post-operative
treatment. Their wide range of extraordinary properties- high density, high viscosity, high biological andchemical inertness, high gas solubility - offer
opportunities for applications in biomedicine andphysical chemistry, as well as subsequently leading toa high interest in scientific development.
An inherent feature to all perfluorocarbons is the socalled perfluoro effect, which describes the energy
shifts of the spectral features due to the stabilization
effect of fluorine in the fluorination process. The
magnitude of the energy shift can subsequently be used
for a classification of a molecular orbital to either bear
σ- or π-character delivering an experimental method
for the orbital classification. Some experimental
studies based on photoelectron and X-ray absorption
spectroscopy have already been performed, but thedevelopment of more complex theoretical models andnew experimental techniques gives opportunities forfurther investigation of perfluorocarbons.
In liquid emulsions several effects need to beaccounted for. Two of the more prominent are theconformation effect and the van der Waals force. The
conformation effect affects peak broadenings and is a
result of excited orbital interactions with surrounding
molecules of different conformations. In the case of
nonpolar systems, the acting van der Waals force is the
London dispersion force, that is, an attractive force
resulting from induced dipoles.

Through the measurements performed at thebeamline BL3U in UVSOR we could obtain X-ray
absorption spectra of several liquid fluoroalkanes andtheir respective hydrocarbons, which are subject toweak van der Waals forces and have a high amount ofdifferent conformational geometries.
Insight into the energetic shift induced byfluorination, the so-called perfluoro effect, and acomprehensive picture of the electronic structure ofliquid fluoroalkanes and their respective parent
hydrocarbon molecules was obtained [1]. In addition
DFT calculations for the hydrocarbons, fluoroalkanes
and stepwise fluorinated hydrocarbon derivatives were
performed. We could reveal a strong involvement of
the conformation effect with the local electronic
structure and relative inertness of liquid fluoroalkanes.
We additionally expose a direct association of different
conformational geometries to the solubility rates of thepresented perfluorocarbons with other liquidcompounds like water and possibly gases like oxygen.

Fig. 1. Sketch of the acquired data for fluoroalkanes
with an indication of the discovered peak broadening
resulting from the conformational effect [1].
[1] T. Brandenburg et al., under review.

100611_Ⅲ_BL4U_5003_長坂

Ⅲ -3. Chemistry

将成

BL4U

In-situ Soft X-Ray Absorption Spectroscopy Measurements of Liquid
Samples by Scanning Transmission X-Ray Microscope
M. Nagasaka, T. Ohigashi, H. Yuzawa and N. Kosugi
Institute for Molecular Science, Okazaki 444-8585, Japan

Two different kinds of molecular liquids can beseparated as two liquid phases by controlling thetemperature due to a phase transition behavior in themixed liquid. In order to reveal the mechanism of sucha phase transition, it is necessary to investigate local
structures of liquid-liquid interfaces of two liquids.
Soft X-ray absorption spectroscopy (XAS) is anelement specific method to study local structures ofliquid. Recently, we have developed a liquid flow cellfor XAS in transmission mode. In the liquid cell, aliquid layer is sandwiched between two 100 nm-thick
Si3N4 membranes, and liquid thickness is controllable
from 20 nm to several μm. By using this liquid cell, we
have revealed local structures of several aqueous
solutions [1]. We have also developed a liquid flow cellcombined with scanning transmission X-ray
microscope (STXM), and measured spatial resolved
XAS of liquid samples [2]. However, the window sizesof Si3N4 membranes (0.5 × 0.5 mm2) are too small tomeasure liquid-liquid interfaces, which are widelydistributed in the liquid layer. In this study, we havedeveloped a liquid flow cell, whose window size is 2 ×2 mm2, to measure spatial resolved XAS of liquidliquid interfaces by STXM. We have measured O Kedge XAS of liquid water for the test of the liquid flowcell.
The experiments were performed at BL4U byconnecting a liquid flow cell to the STXM system. The
liquid cell is in the atmospheric helium condition. The
liquid layer is sandwiched between two 100 nm-thick
Si3N4 membranes with the window size of 2 × 2 mm2.
The membranes are supported by Si frames with the
thickness of 0.2 mm. In order to adjust the liquid
thickness, 20 μm-thick Teflon spacers are included
between two Si frames of the membranes. Liquidsamples are exchanged in situ by using a tubing pumpsystem. Temperature of a liquid sample is controlled
by setting a Cu plate connected with a chiller system.
Figure 1 shows a soft X-ray transmission image ofliquid water at the incident photon energy of 550 eV.
Because the left part of the image is a Si frame, soft Xray is not transmitted. On the other hand, soft X-rays
are transmitted in the right part due to the existence ofliquid water. We have observed line shape structures,in which thick liquid layer exists, with the distance of
250 μm from the edge of the Si frame. Figure 2 shows
O K-edge XAS of liquid water. The beam spot of soft
X-ray is set to the line shape structures in the liquid
layer to obtain appropriate thickness of liquid layers
for XAS in transmission mode. The thickness of aliquid layer is 480 nm. The intensity ratio of pre-edge(535 eV) and main-edge (538 eV) is 0.39, and isconsistent with our previous results [3].
In the future plan, we will measure spatial resolved
XAS images of liquid-liquid interfaces by using thisliquid flow cell, and revealed the mechanism of thephase transition of two liquid structures.

Ⅲ-3

Fig. 1. Soft X-ray transmission image of liquid waterat the incident photon energy of 550 eV.

Fig. 2. O K-edge XAS of liquid water, in which thebeam spot of soft X-ray is set to the line shapestructures in the liquid layer shown in Fig. 1.
[1] M. Nagasaka et al., J. Electron Spectrosc. Relat.
Phenom. 200 (2015) 293.
[2] T. Ohigashi et al., AIP Conf. Proc., in press.
[3] M. Nagasaka et al., in preparation.

101

621_Ⅲ_BL4B_215_彦坂泰正.docx
Ⅲ -3. Chemistry

BL4B

Auger Decay of Condensed Water Investigated with a Magnetic Bottle
Electron Spectrometer
R. Mashiko1, K. Soejima1, E. Shigemasa2 and Y. Hikosaka3

Department of Environmental Science, Niigata University, Niigata 950-2181, Japan
2
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
3
Graduate School of Medicine and Pharmaceutical Science, University of Toyama, Toyama 930-0194, Japan1

Ⅲ-3

Slow electron formation relevant to inner-shell
photoionization of gas phase H2O was investigated bymulti-electron coincidence spectroscopy [1]. It was
found that autoionization from O fragment produced
by dissociation of Auger final H2O2+ states is theimportant source of the slow electron formation. Suchslow electron formation from the ionization of watermolecules has received particular attention, in
connection with DNA strand breaks in living cells
exposed to ionizing radiations. The DNA strand breaks
are largely caused by the impact of electrons emitted
from the ionization of water molecules andbiomolecules surrounding the DNA. Here, themajority of the electrons have kinetic energies of lessthan 20 eV, and the efficiency of the DNA strand
breaks is known to be strongly dependent on theincident electron energy of the impacting electrons,
due to its resonant character. Thus the knowledge ofthe energy distribution of the slow electrons isimportant in modeling the radiation damages of living
cells. In this study, we have investigated the slow
electron emission process of condensed H2O irradiatedwith soft x-ray.
The experiment was performed at the beamline
BL4B under the single bunch operation of the storage
ring. The synchrotron radiation from a bending magnetof the strange ring was monochromatized by a grazing
incidence monochromator using a varied-line-spacing
plane grating. The monochromatized light was
focused onto a copper wire. Water molecules wereadsorbed on the surface of the wire, by continuously
cooling the wire down to the liquid nitrogentemperature, under its exposition to the base pressure(~1.8×10-8 Torr). Electron coincidence measurements
were carried out with the magnetic bottle electron
spectrometer [2] whose schematic is shown in Fig. 1.
Coincidence datasets were accumulated forelectrons emitted from the copper wire on irradiationof 738.2 eV photons. The two-dimensional map in Fig.
2 displays the energy correlation of the coincident
electrons included in the coincidence datasets, where
the coincidence counts are plotted as a function offaster (horizontal) and slower electron energies(vertical). A clear structure running horizontally is
associated with the coincidences between the O1s
photoelectrons and the Auger electrons fromcondensed water.
We have inspected three-fold coincidences among
the O1s photoelectron, Auger electron and slow
electron, in order to investigate the energy distributionof the slow electrons emitted after the Auger decay.

The energy distribution (not shown) does not exhibit
any tangible structures ascribable to autoionizationfrom O: fragments. This observation implies that
dissociations forming O* fragments are suppressed in
the condensed phase.

Fig. 1. Schematic of the magnetic bottle electron
spectrometer.

Fig. 2. Two dimensional plot of energy correlation
between photoelectron and Auger electron emitted in
the inner shell ionization of condensed watermolecules.
[1] Y. Hikosaka et al., J. Chem. Phys. 137 (2012)
191101.
[2] Y. Hikosaka et al., J. Ele. Spectrosc. Rel. Phenom.
192 (2014) 69.

102

Ⅲ -3. Chemistry

631_Ⅲ_BL5B_557_金安達夫.docx

BL5B

Improvement of the VMI Spectrometer for Photoelectron Imaging
Experiment
T. Kaneyasu1, Y. Hikosaka2, H. Iwayama3 and E. Shigemasa3

SAGA Light Source, Tosu 841-0005, Japan
Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
3
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
1

2

Velocity map imaging (VMI) [1] is one of thepowerful methods for measuring the velocity
distribution of charged particles emitted in various
atomic and molecular processes. We employed a VMI
spectrometer for the experimental investigation on
photoionization of gas-phase atoms by circularly
polarized undulator radiation which carries orbital
angular momentum [2]. Since the VMI spectrometerused in our study was originally developed for thenegative ion imaging [3], it was found that slight
modification of the spectrometer was necessary for
improving the electron image quality.
The details of the VMI spectrometer is described inref. [3]. Briefly, the spectrometer consists of a repeller
plate, electrostatic lenses and a drift tube followed bya two dimensional position sensitive detector. The
photoelectrons having same initial velocities arefocused to the same detector's position independent of
the ionization point by applying the inhomogeneouselectrostatic filed to the ionization region. When thecylindrical symmetry is assumed, three-dimensional
vectors of the photoelectrons can be reconstructedfrom the projected two-dimensional image.
The improvements of the VMI spectrometer are as
follows. Firstly we introduced a magnetic shieldaround the drift tube for reducing the stray magnetic
field in the electron drift space. Next we replaced therepeller electrode with a mesh-type one. This isbecause secondary electrons are efficiently produced
from the electrode surface by photoions colliding withthe repeller plate. Finally we constructed a new frame
for supporting the experimental chamber, allowing
precise positioning of the spectrometer's center withrespect to the photon beam axis.
Following the improvements, performance test of
the VMI spectrometer has been carried out at BL5B.
The images and angular distributions of the He 1s andAr 3p photoelectrons are shown in Figs. 1 and 2,
respectively. The electric vector of the photon beam isparallel to X-axis of the image. The intense ringshaped structures observed in the images correspondto the photoelectrons, while secondary electrons are
weakly distributed inside the ring structures. The
secondary electron emission is well suppressedcompared to the previous setup consisting of the platetype repeller electrode. The image distortion observedin the previous measurements is reduced byintroducing the magnetic shield. Photoelectron angular
distributions are converted from the raw images

without any background subtraction and image
corrections. The measured angular distributions are
fairly in agreement with the calculation results,
confirming that image quality of the VMI spectrometeris sufficiently improved for the photoelectron imaging
experiment.

Ⅲ-3

Fig. 1. (a) Projected image and (b) angular
distributions of He 1s photoelectrons measured athν=27.6 eV. Solid curve represents the calculation for
β=2.

Fig. 2. (a) Projected image and (b) angular
distributions of Ar 3p photoelectrons measured athν=21.0 eV. Solid curve represents the calculation
result for β=0.84.
[1] A. T. J. B. Eppink and D.H. Parker, Rev. Sci.
Instrum. 68 (1997) 3477.
[2] T. Kaneyasu et al., UVSOR Activity Report 2014,42 (2015) 110.
[3] Y. Hikosaka and E. Shigemasa, J. Electron Spectrsc.
Relat. Phenom. 148 (2005) 5.

103

641_Ⅲ_BL6U_220_岡田和正.docx
Ⅲ -3. Chemistry

BL6U

Auger Spectra Measured in Coincidence with the Photofragment Ions
Formed after Migration: 3,3,3-Trifluoropropene at the C K-Edge
R. Tateishi1, T. Kaneda1, H. Iwayama2, 3, M. Kono4, 5, K. Okada1 and E. Shigemasa2, 3

Department of Chemistry, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
2
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan3
School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585,
Japan
4
Senri International School of Kwansei Gakuin, Minoh 562-0032, Japan
5
RSPE, Australian National University, Canberra, ACT 0200, Australia
1

Ⅲ-3

after a fluorine-atom migration.
Figure 1 gives resonant Auger spectra measured incoincidence with the C2H3+ and C2H3F+ detection. The
spectra have been obtained after subtraction of thecontribution from photoelectrons. Both ions areproduced by the C2–C3 bond rupture, with the only
difference being with and without the migration before
fission. It can be seen that the spectrum coincident withC2H3F+ has a specific peak at the electron kinetic
energy of 265.7 eV, whereas that coincident with
C2H3+ spreads widely with two distinct peaks. The
result reveals that the migration occurs from such
limited Auger-final states.

Inner-shell excited molecules relax into molecular
cations in different states through Auger decays. The
cations are in general unstable and dissociate rapidly
into fragment ions. In many hydrocarbon molecules aphotoexcitation can cause a rapid geometry change inthe molecule. Such migration has also been observedfor photoexcitation of molecules at the inner-shelllevel. In the case of the inner-shell excitation andionization of acetylene, for example, ion yield spectraof H2+ and CH2+ were observed [1] and the C2+/H2+ ion
pair was detected [2], indicating a proton migration.
We have recently concerned ourselves with the Augerfinal states connecting to particular dissociation
channels [3]. This report focuses on the rapid
migration in the 3,3,3-trifluoropropene (TFP)
molecule excited at the C K-edge. We have employed
the Auger-electron–photoion coincidence (AEPICO)
method to obtain information on the correlation
between photofragment ions formed after migration
and Auger-final states of the molecular ion.
The experiments were performed on the soft X-ray
beamline, BL6U. The experimental setup has been
described elsewhere [3,4]. Synchrotron radiation wasirradiated at right angles to the effusive beam of the
TFP sample. The pressure of the main chamber was
kept at 4.0 × 10−4 Pa during the measurements. Auger
electrons traveling through a double toroidal analyzer
tube were detected with a position sensitive detector.
The pass energy was set to 400 eV. Photofragment ionsproduced in the ionization region were extracted
toward a time-of-flight mass spectrometer by a pulsed
electric field applied just after the Auger electron
detection. AEPICO data were obtained as list-mode
files, containing a series of a set of the detected
electron positions and the ion arrival times. The photon
energies of 284.5 and 310.0 eV were used as typicalresonant excitation and photoionization, respectively.
A correlation map of kinetic energy of the emitted
Auger electrons versus m/z of photofragment ions canbe depicted from the coincidence data. A variety ofphotofragment ions is found, such as CHn+, F+, C2Hm+,
CFm+, C2HmF+ and so forth, where n = 0–3 and m = 1–
3. They form islands on the map. Auger spectra
coincident with particular ions can be obtained byextracting the region of interest on the map. In thisstudy we focus on the C2H3F+ ion, which is produced

Fig. 1. Resonant Auger spectra measured incoincidence with detection of the C2H3+ and C2H3F+
photofragment ions. The contribution from photoelectrons has been subtracted.
[1] M. N. Piancastelli et al., J. Chem. Phys. 117 (2002)
8264.
[2] J. Laksman et al., J. Chem. Phys. 131 (2009)244305.
[3] S. Ishikawa, K. Okada, H. Iwayama and E.
Shigemasa, UVSOR Activity Report 42 (2015) 121.
[4] T. Kaneyasu, Y. Hikosaka and E. Shigemasa, J.
Electron Spectrosc. Relat. Phenom. 156-158 (2007)
279.

104

651_Ⅲ_BL6U_518_彦坂泰正.docx

Ⅲ -3. Chemistry

BL6U

Dissociation of CH3OH Dication Studied by an Electron-Ion Coincidence
MethodM. Higuchi1, H. Iwayama2, E. Shigemasa2 and Y. Hikosaka3

Department of Environmental Science, Niigata University, Niigata 950-2181, Japan
2
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
3
Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan1

A molecule absorbing a soft x-ray photon undergoes
inner-shell photoionization and subsequently Auger
decay. Because two electrons are emitted through thissequential process, the molecule with two positive
charges, called dication, is produced. The dication
often dissociates into ion pairs, due to the Coulomb
repulsion. In this work, we have studied the ion-pairdissociation of CH3OH dication states by an electronion coincidence method.
The experiment was performed at the undulator
beamline BL6U of the UVSOR facility. We used anelectron-ion coincidence setup consisting of a toroidal
electron analyzer and an ion momentum imaging
analyzer [1,2].
Figure 1 shows a time-of-flight spectrum of ionsproduced after the C1s inner-shell ionization of
CH3OH. Peaks for H+ and H2+ fragments can beobserved in 800-1100 ns. The manifold seen in 19002400 ns is allocated to the fragments resulting from thedissociations comparing with the CO bond cleavage.
The fragments keeping the C-O framework areobserved in 2800-3000 ns. Hereafter, we focused on
the dissociation producing H2+ fragments. The twohydrogen atoms can come from C side only, but thehydrogen atom originally at the O-side can contribute.
In practice, the time-of-flight spectrum measured for
CH3OD (not shown) exhibits both H2+ and HD+ peaks.
Figure 2 shows C1s Auger spectra filtered bydetections of H2+ (blue) and HD+s (red), compared to
the normal Auger spectra (black). While thecoincidence Auger spectrum for H2+ shows a peakaround 43 eV, the HD+ peak lies around 35 eV. Thisobservation implies that formation of HD+ fragments
is involved by lower dication states which may belonger lifetime and thus allows the exchange ofhydrogens of O-side and C-side before dissociation.
Figure 3 shows correlations of ion fragments formedin pair, observed for CH3OD. The counterparts of HD+
fragments are mainly the fragments which keeps CO
bond, i.e. COH+ and COH2+. On the other hand, half of
the H2+ fragments are formed in pair with thefragments resulting from CO-bond braking, e.g. CH2+
and CH3+.

Fig. 1. Time-of-flight spectrum of ions produced after
C1s inner-shell ionization of CH3OH.

Ⅲ-3

Fig. 2. Coincidence Auger spectra filtered bydetections of H2+ (blue) and HD+ fragments (red),compared to the normal Auger spectra (black).

Fig. 3. Correlation map for ion pairs detected incoincidence.
[1] T. Kaneyasu, Y. Hikosaka and E. Shigemasa, J.
Electron Spectrosc. Rel. Phenom., 156-158 (2007) 279.
[2] Y. Hikosaka, Y. Shibata, K. Soejima, H. Iwayama
and E. Shigemasa, Chem. Phys. Lett., 603 (2014) 46.

105

661_Ⅲ_BL6U_518_彦坂泰正.docx
Ⅲ -3. Chemistry

BL6U

Dissociation Dynamics of Doubly-Ionized Water Molecules
M. Kikuchi1, M. Higuchi1, H. Iwayama2, E. Shigemasa2 and Y. Hikosaka3

Department of Environment Science, Niigata University, Niigata 950-2181, Japan
2
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
3
Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan1

Ⅲ-3

Interaction of a water molecule with high-energy
radiation may lead to inner shell ionization, and an
inner shell electron is emitted as a photoelectron.
Subsequent Auger decay generates a doubly-ionizedwater molecule which mainly dissociates to an ion pairby the Coulomb repulsion. In this work, weinvestigated to the dissociation processes of the
doubly-ionized water molecule.
The experiment was performed at the beamline
BL6U, by using an Auger electron-ion coincidence
spectrometer consisting of a double toroidal electron
analyzer and an ion time-of-fight (TOF) analyzer. We
measured Auger electron-ion coincidences for gas
phases D2O as well as H2O. Soft X-ray was irradiatedto the sample gases introduced to the ionization point.
Kinetic energies of the Auger electrons were
determined by the arrival positions on the position
sensitive detector of the double toroidal electron
analyzer. On the detection of the individual Auger
electron, an electric field was applied to the ionization
point so that fragment ions are measured by the ion
TOF analyzer. Auger electron energy determined by
the double toroidal electron analyzer indicates thebinding energy of the formed doubly-charged ion
states, and TOFs of the ions observed in coincidenceswith the Auger electron reveal the resultant ion-pair.
Figure 1 shows the correlations of TOFs of ion pairs
observed in coincidence with all Auger electrons.
Clear correlations corresponding to the D++OD+ ion
pair and the D++O+ ion pair are observed. The former
ion pair results from the two-body dissociation of
D2O2+ → D++OD+, and the later from the three-bodydissociation of D2O2+ → D++O++D. It is estimated that,from the coincidence counts of these two structures inFig. 1, the two-body dissociation is about 4.5 times
more probable than the three-body dissociation.
The black curves in Fig. 2 are the Auger spectra of(a) D2O and (b) H2O, which show a band structure in
35-50 eV. The coincidence Auger spectra filtered forthe two-body dissociation are represented in red, andthose filtered for the three-body dissociation is in blue.
In both water samples, the two-body dissociationaccounts for the majority and yields the peak around
42 eV. In the higher energy side of the band structure,
the fraction of the three-body dissociation increases.
Comparison between the spectra for D2O and H2O
implies that the contribution from the three-bodydissociation is higher in H2O than in D2O. This isprobably because elongation of the O-H bond becomesslower by the deuteration.

106

D+

OD+

O+

Fig. 1. Correlations of TOFs of ion pairs observed incoincidence with all Auger electrons.
(a)

D++OD+

D++O++D(b)

H++OH+

H++O++H

Fig. 2. Total Auger spectra (black) of (a) D2O and (b)H2O, (a) D2O, and coincidence Auger spectra filtered
for the two-body dissociation (red) and for the threebody dissociation (blue).

671_Ⅲ_BL6U_9601_岩山洋士.docx

Ⅲ -3. Chemistry

BL6U

Site-Specific Production of H3+ Ions Following Core Ionization of CH3Cl
H. Iwayama1, 2 and E. Shigemasa1,2

1
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585,
Japan

2

Trihydrogen cation H3+ is one of the most interesting
molecules in diverse fields from chemistry toastronomy because it is the simplest triatomic
molecule and plays an important role in the interstellar.
While the H3+ ions can be mainly generated from theproton transfer reactant (H2 + H2+ → H3+ + H), it was
shown that unimolecular reactions of soft x-ray
irradiated CH3X molecules (X=Cl, OH, CN, etc.)
also have small contributions of H3+ formation in theinterstellar [1].
In this work, we investigate the H3+ production
mechanism of soft x-ray irradiated CH3Cl moleculeswith using an Auger-electronion coincidence
technique, which allows us to correlate Auger final
dicationic states with product ions. From coincidence
Auger spectra, we reveal dicationic states which form
the H3+ ions.
The Auger-electronion coincidence measurements
were performed on the undulator beamline BL6U at
UVSOR. The electron ejected at 54.7° with respect tothe electric vector of the incidence radiation wereanalyzed in the energy by a double toroidal analyzer(DTA), while ions were extracted from the interaction
region into a momentum spectrometer by a pulsed
electric field according to the electron detection.
Arrival position on the detector and time-of-flight(TOF) of ions and electrons were recorder for every
event. The pass energy of the DTA was set to 200 eV
for observing the Auger electrons. The corresponding
electron energy resolution was about 1.9 eV. All
signals from the detectors were recorded with an 8ch
TDC board. We used the photon energies of 220 and
302 eV for the Cl 2p and C 1s core-ionized states,
respectively. To obtain total ion TOF spectra, we alsomeasured ions in coincidence with the Cl 2p and C 1s
photoelectrons instead of the Auger electrons.
Figure 1 shows total ion TOF spectra following the
Cl 2p and C 1s photoionization. Main fragment ionsare Hn+ (n=1,2,3), CHn+ (n=0-3), Cl+ and CHnCl+(n=0,1,2). CH3Cl+ ions were not observed since theparent molecules following the Auger decay are
doubly charged. Doubly charged ions such as Cl++ and
CHnCl++ (n=0-3) were also observed. The mostremarkable difference in fragmentation between the Cl
2p and C 1s photoionization is the relative abundanceof H3+ ions. The relative intensity of H3+ ions for the
Cl 2p photoionization is ten times larger than that for
the C 1s photoionization.
Figure 2 shows the coincidence Auger spectra with
Hn+ (n=1,2,3) ions in the binding energy scale, incomparisons with the total Auger spectra. It is clearlyseen that the formation of the H3+ ions is related to only
the lowest band around the binding energy of 32 eV for
both the Cl 2p and C 1s photoionization, while the total
Auger and coincidence Auger spectra with H+ and H2+ions are quite different in the two cases. In order tounderstand the mechanism of such a site-specificproduction of the H3+ ions, theoretical calculations for
the Auger final states of the CH3Cl molecule are highly
desired.

Ⅲ-3

Fig. 1. Time-of-flight spectra of ions taken incoincidence with (a) Cl 2p and (b) C 1s photoelectrons.

Fig. 2. Total and coincidence Auger spectra with Hn+ions (n=1,2,3) for (a) Cl 2p and (b) C 1s
photoionization.
[1] S. Pilling et al., Mon. Not. R. Astron. Soc. 375(2007) 1488.

107681_Ⅲ_BL6U_9601_岩山洋士.docx
Ⅲ -3. Chemistry

BL6U

Molecular Dynamics of Core Excited N2 Molecules Studied by an
Auger-ElectronPhotoion Coincidence Method
H. Iwayama1, 2 and E. Shigemasa1,2

UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585,
Japan
1

2

Ⅲ-3

A core shell electron in a molecule can be promoted
to unoccupied orbitals when a photon energy is tuned
to resonances. The core excited molecule thus createdis highly unstable and relaxes either by radiative decay
or Auger electron emission. For light elements (Z<26),
the Auger decay is the dominant process after the core
excitation, and various cationic states are formed
through the Auger electron emissions. In some cases,
core excited molecules become dications by the double
Auger decay. The stability and dissociation dynamics
of the Auger final states depend on their charge statesand electronic states, which can be investigated byusing an Auger-electronphotoion coincidence
technique. In this work, we investigate the stability anddissociation dynamics of core excited N2 molecules.
The Auger-electronion coincidence measurements
were performed on the undulator beamline BL6U at
UVSOR. The Auger electrons and product ions were
measured in coincidence by a double toroidal electron
analyzer (DTA) and an ion momentum spectrometer,
respectively. The pass energy of DTA was set to 400
eV. All signals from the ion and electron delay-line
detectors were recorded with an 8ch TDC board. The
photon energy was tuned to 401.1 eV, whichcorresponds to the resonance energy of the N 1s →π*excitation.
Figures 1(a) and (b) show total and coincidence
Auger spectra with N2+ and N+ ions, respectively. Theenergy scale of the bottom axis is obtained bysubtracting the kinetic energy (KE) of Auger electrons
from the excitation energy of 401.1 eV. Here this isdefined as remaining energy. For cations, theremaining energy corresponds to the binding energy,
while it is slightly higher than the binding energy for
dications, due to the ejection of a second Auger
electron. Below the remaining energy of ~25 eV, weobserve only N2+ ions. This is consistent with the factthat the lowest dissociation limit energy of N+ + N is
24.2 eV. On the other hand, we find only N+ ions above
the binding energy of ~25 eV. To identify thecontribution of dications resulting from the double
Auger decay, we show a coincidence Auger spectrumwith N++N+ fragment pairs in Fig. 1(c). The spectrum
shows the double Auger decay processes cancontribute to the Auger final states above theremaining energy of 48 eV.
Figure 2 shows a two-dimensional Auger-electron
ion coincidence map. The vertical and horizontal axes
correspond to the kinetic energy release (KER) of ionsand the remaining energy, respectively. We find several
diagonal structures, suggesting several dissociation
pathways. Dashed lines in Fig. 2 represent lowest
dissociation limit energies for N+ + N and N+ + N+. The
horizontal structure at the remaining energy of 48 eV
and KER of 0 eV corresponds to metastable N2++ ions.
Above the remaining energy of 40 eV, the double
Auger decay process is dominant. The detail analysis
is in progressFig. 1. Total (black line) and coincidence Auger
spectra (red filled area) with (a) N2+ ions, (b)N+ ionsand (c) N++N+ fragment pairs.

Fig. 2. A two-dimensional Auger-electron-photoion
coincidence map. Diagonal dashed lines A and B
represent a plot of the KER as a function of theremaining energy for lowest dissociation limits ofN++N and N++N+, respectively.

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691_Ⅲ_BL6B_828_長坂将成.docx

BL6B

Infrared Microscopy of T- Shape Microfluidics
M. Nagasaka1, H. Yuzawa1, M. Nakano1, N. Takada1, M. Aoyama1, E. Rühl2 and N. Kosugi1
Institute for Molecular Science, Okazaki 444-8585, Japan
Physikalische Chemie, Freie Universität Berlin, Takustr. 3, D-14195 Berlin, Germany
1

2

Microfluidics is a chemical technique to realize
highly efficient chemical reactions in liquids andsolutions. The mechanism of such reactions in
microfluidics has been studied by thermal lensmicroscopy [1] and nuclear magnetic resonancemethods [2]. It is difficult to apply spectroscopic
techniques to microfluidics, especially in the soft Xray regime, since this radiation cannot penetrate a
microfluidics cell. Recently, we have developed aliquid cell for soft X-ray absorption spectroscopy(XAS) of liquids in the transmission mode [3]. The
liquid layer in the cell is sandwiched between two
Si3N4 membranes with the thickness of 100 nm totransmit soft X-rays.
The purpose of this study is to measure XAS andinfrared (IR) spectra of structured liquids bydeveloping a microfluidic cell consisting of Si3N4
membranes. In the report, we show results from IR
microscopy of a T-shaped microfluidics cell during themixing process of water and ethanol for a proof-ofconcept study of a cell that is currently underdevelopment.
The experiments were performed by using the IR
microscopy IRT-7000 at BL6B combined with adeveloped microfluidic cell. A T-shape microfluidics
setup with a width of 50 μm is made from PDMS resin
which is covered by a 100 nm Si3N4 membrane (NTTAT). The adhesion of PDMS to the Si3N4 membrane isrealized by pressing a Si frame of the membrane with
O-rings. Ethanol and water are mixed in the T-shapedcell with a flow rate of 50 μL/min by using syringe
pumps. The spatial resolution of 30 × 30 μm2 isreached by using a ×16 Cassegrain mirror. IR spectra
are taken by detecting the reflected infrared light withan MCT detector.
Figure 1 shows the 2D plot of the IR absorbance in
the T-shape microfluidics at 3507 cm-1, which is due tothe OH stretching mode of water. Ethanol is flowed in
the left hand part and water is injected into the righthand part. The ethanol-water mixture is flowed to thelower part after the junction of the liquids. Figure 2
shows IR spectra at different positions of the setup,considering that the absorbance at 3507 cm-1 of wateris larger than that of ethanol. The IR spectra at thepositions A, B, and C after the junction of two liquids
are similar to each other. The results indicate, however,that the hydrogen bonds between water decrease
rapidly after mixing of both liquids.
In subsequent studies, we intend to investigate IR
microscopy of chemical reactions using our T-shaped
microfluidics setup.

Ⅲ-3

Fig. 1. The 2D plot of the IR absorption at 3507 cm-1
in the T-shaped microfluidics cell.

Fig. 2. IR spectra at different positions of the
microfluidics cell. The positions of data acquisition are
shown in Fig. 1. The dashed line indicates thewavenumber of 3507 cm-1.
[1] T. Kitamori et al., Anal. Chem. 76 (2004) 53.
[2] T. Tsukahara et al., Angew. Chem. Int. Ed. 46(2007) 1180.
[3] M. Nagasaka et al., J. Electron Spectrosc. Relat.
Phenom. 200 (2015) 293.

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