Ⅲ-3
ChemistryⅢ -3. Chemistry

BL1U

Limitations in Photoionization off Helium by an Extreme Ultraviolet Vortex
T. Kaneyasu1, Y. Hikosaka2, M. Fujimoto3, M. Katoh3, 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, Japan1

2

We report the experimental investigation on thephotoionization of helium atoms irradiated with acircularly polarized extreme ultraviolet (XUV) vortex
beam produced by a helical undulator [1]. The XUVvortex has a helical wavefront and carries orbital
angular momentum (OAM) as well as spin angularmomentum associated with it circular polarization. In
recent years, several theoretical works have beenreported on the photoionization and photoexcitation of
atoms by OAM-carrying photons [2]. Differing fromplane-wave photons, a violation of the standard
electric dipole selection rules is predicted for vortex,
as a consequence of the transference of the OAM to theinternal degrees of freedom of the atom. In contrast tothese advances in theory, to our knowledge, there has
been no experimental work on vortex-matterinteractions in the short wavelength regime, owing to
the technical difficulty of producing brilliant andenergy-tunable vortex beams.
The experiment was carried out at the undulator
beamline BL1U. The experimental setup is shown in Fig.
1. The XUV vortex beams at about 30 eV photon energy
were produced by a helical undulator as the higher
harmonics of its radiation because the nth harmonic offaxis radiation from a helical undulator carries OAM of(n-1)ħ per photon [3, 4], as a result of the spiral motionof electron which naturally emits electromagnetic wave
with a helical wavefront [5]. To avoid possible
distortions of the helical wave front characterizing the
XUV vortex, we did not use any optical elements in theexperiment. The interaction point was placed at about
11 m downstream from the undulator, where the sample
gas was admitted from an aperture. The central part of
the undulator radiation was cut out by a 1-mm-diameter
pinhole. Photoelectron angular distributions of helium
atoms were measured by using a velocity map imaging(VMI) spectrometer.
Figure 2 shows the angular distributions measured forthe first, second and third harmonics, corresponding toplane-wave photons (l=0), and XUV vortices of l=1 and
2, respectively. While the violation of the electric dipole
transition rules has been predicted for interactions
between vortices and atoms, the photoelectron angular
distributions are well reproduced by the dipole
components alone, and non-dipole contributions are notdetected within the experimental uncertainty. Thisobservation can be explained by considering the
localized nature of the helical phase effect of the vortex
on the interaction with atoms, and demonstrates that
non-dipole interactions induced by vortex are hardly
observable in conventional gas-phase experiments.

101

Fig. 1. Experimental setup used for photoionization
experiment of helium atoms by the XUV vortex. The
XUV vortex produced by the APPLE-II undulator isintroduced into the interaction point without any
optical elements.

Ⅲ-3

Fig. 2. Photoelectron angular distributions of helium
atoms measured for the (a) first, (b) second and (c)third harmonics from helical undulator. The solid blue
curves represent fits assuming electric dipole transition.
The dotted green curves in (b) and (c) show the angulardependence of the photoelectron expected for nondipole transitions induced by the OAM carried by the
XUV vortex.
[1] T. Kaneyasu et al., Phys. Rev. A 95 (2017) 023413.
[2] A. Picón et al., New J. Phys. 12 (2010) 083053.
[3] S. Sasaki and I. McNulty, Phys. Rev. Lett. 100(2008) 124801.
[4] J. Bahrdt et al., Phys. Rev. Lett. 111 (2013) 034801.
[5] M. Katoh et al., Phys. Rev. Lett. 118 (2017) 094801.

Ⅲ -3. Chemistry
BL1U
BL1U

Optical Vortex or Polarized UV Light Induced Supramolecular Chiral
Orientation of an Achiral Metal Complex in a Soft Polymer Matrix
1

Ⅲ-3

M. Takase1, T. Akitsu1 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, Japan

It is well known that a lot of organic polymers ofliquid crystals containing azo-groups exhibit opticalanisotropy after polarized UV light irradiation(Weigert effect). In recent years, we havesystematically investigated organic/inorganic hybridmaterials composed of chiral Schiff base metal
complexes and azo-compounds in PMMA polymer
films [1], chiral Schiff base metal complexes without
azo-groups in protein matrix [2], and achiral Schiffbase metal complex without azo-group in PVA
polymer film [3] to discuss induced optical anisotropy
after linearly polarized UV light irradiation or induced
chiral supramolecular arrangement after circularly UV
light irradiation.
In this time, we prepared organic/inorganic hybridmaterials composed of water soluble binuclear Zn(II)Schiff base complex (Zn2L) without azo-compound in
a PVA film to investigate not only linearly or circularly
polarized UV light induced molecular orientation but
also optical vortex UV light induced molecularorientation or changes by means of UVSOR BL1U.
As shown in Fig. 1, we have synthesized andcharacterized new Schiff base dinuclear Zn(II)complex involving chroride axial ligands and also
prepared PVA polymer cast films. Without
photochrmoic additives, optical dichroism at chargetransfer bands could be observed after linearlypolarized UV light irradiation with electric field vectorof polarization due to increasing anisotropy ofmolecular orientation of the complexes directly. For
example, the related Ni(II) complex most clearly
exhibited anisotropy after linearly polarized UV lightirradiation for 10 min. Fig. 2 exhibits angulardependence of polarized UV-vis spectra (absorbance at
367 nm) of Ni(II) complex. The Zn(II) complex also
indicated similar behavior to Ni(II) one.
Comparing with several CD data of control
experiments (only PVA film or hybrid materials,
solutions or film, wavelengths or orbital angularmoment dependence of UV light), we could derive
preliminary results that optical vortex or polarized UVlight (Fig. 3) induced molecular orientation of theZn(II) complex in hybrid materials.

Fig. 1. Molecular structure of Zn(II) complex.

Fig. 2. Angular dependence of polarized UV-vis
spectra (367 nm) of Ni(II) complex in PVA film after
linearly polarized UV light irradiation (< 350 nm).

Fig. 3. CD spectra of of Zn(II) complex in PVA film
after optical vortex (l=0) UV light irradiation (380 nm).
[1] N. Sunaga, C. Kominato, N. Ishida, M. Ito, T. Akitsu,
T. Konomi and M. Katoh, Azobenzene: Aspects,
Applications and Reserach (Nova Science Publishers,Inc., New York, 2017).
[2] E. Tsuda, Y. Mitsumoto, K. Takakura, N. Sunaga, T.
Akitsu, T. Konomi and M. Katoh, J. Chem. Chem. Eng.
2 (2016) 53.
[3] M. Takase and T. Akitsu, Polymers Book Series#1: Polymer science: research advances, practicalapplications and educational aspects (Formatex
Research Center, Badajoz (Spain), 2016).

102
Ⅲ-3-2

Ⅲ -3. Chemistry
BL3U
BL3U

Local Structure of Crown Ether Inclusion Complex in Water by Soft X-ray
Absorption Spectroscopy I. Interaction between Crown Ether and Ca2+
H. Yuzawa, M. Nagasaka and N. Kosugi

Institute for Molecular Science, Okazaki 444-8585, Japan

unsaturation (disordered coordination symmetry) [4].
In addition, the pore diameter of 18-crown-6 is larger
than the ionic diameter of Ca2+ (1.98 Å), whose size isfitted for that of 15-crown-5. Thus, Ca2+ would becoordinated by 18-crown-6 more unsymmetricallythan the other samples with its molecular frame folding.
In the 15-crown-5 contained sample (green line), thepeak shape around 351.6 eV is more symmetrical thanthe other samples. This may be because the coordination
symmetry is the highest in the samples [4].
Therefore, Ca L-edge XAS can be used as aneffective indication of the coordination symmetry ofcrown ether complexes.

Ⅲ-3

Intensity / arb. units

Since the interaction in inclusion complexes showsa crucial role for life phenomena etc. but is notinvestigated in detail with conventional spectroscopic
analysis [1], new methodologies are still required for
detailed analysis of the interaction. Our research group
has developed a liquid cell for the soft X-ray XAS in
the transmission mode and has applied it tomeasurements of various aqueous solutions [2]. In thepresent study, we have extended this method to themeasurement for the inclusion complex system ofcrown ethers in water to observe the interaction.
Especially, we paid attention to the influence of thepore diameter of crown ether on the interaction ininclusion complexes by using three different crownethers. In this part, we report Ca L-edge XAS ofaqueous Ca(SCN)2 crown ether solutions.
The experiments were carried out at BL3U. Aqueous
solution samples (molar ratio, Ca(SCN)2 : H2O = 1 : 59,
Ca(SCN)2 : H2O : 18-crown-6 = 1 : 59 : 1, Ca(SCN)2 :H2O : 15-crown-5 = 1 : 59 : 1 and Ca(SCN)2 : H2O : 12crown-4 = 1 : 195 : 1) were prepared by using thecommercial reagents without further purification. Afterthe liquid cell which is composed of two Si3N4
membranes was filled with the liquid sample, thethickness (absorbance) of liquid samples was optimizedby controlling the He pressure around the cell and thenthe Ca L-edge XAS was measured. The photon energy
was calibrated by using the C K-edge XAS spectrum of
the proline thin layer.
Figure 1 shows the obtained Ca L-edge XAS spectra.
Two intense absorption peaks are assigned to Ca 2p3/2→ 3d excitation around 349.3 eV and Ca 2p1/2 → 3d
one around 352.6 eV. These peak energies are slightly
shifted to the lower energy (orange, green and bluelines in inset figures) compared with that in the simple
aqueous Ca(SCN)2 solution (red line). On the other
hand, in the case of aqueous Ca(SCN)2-EtOH solution(molar ratio, Ca(SCN)2 : H2O : EtOH = 1 : 59 : 3), theenergy shift is not observed (data not shown). This
result indicates that the observed energy shift arises
from the formation of crown ether-Ca2+ inclusion
complex.
In the lower energy regions for the intense peaks,
fine absorption structures in weak intensity areobserved (Fig. 1, upper figure) mainly because thecrystal field splitting of 3d states [3]. In the 18-crown6 contained solution (orange line), the shapes of peaks
around 348.4 and 351.4 eV is clearly different from theother samples. Compared with the previous report for
the Ca L-edge spectra of solid CaF2, the obtained
difference is similar to the change for the coordinative

349.3

348

352.6

350
352
354
Photon Energy / eV

Fig. 1. Ca L-edge soft x-ray absorption spectra ofaqueous Ca(SCN)2 solution (red line), that containing
18-crown-6 (orange line), that containing 15-crown-5(green line) and that containing 12-crown-4 (blue line).
Upper figure is magnified view of small peaks and two
inset figures are magnified views of two intense
absorption (Ca-L3 and L2) peaks.
[1] G.W. Gokel, W.M. Leevy and M.E. Weber, Chem.
Rev. 104 (2004) 2723.
[2] M. Nagasaka, H. Yuzawa and N. Kosugi, J. Spectrosc.
Relat. Phenom. 200 (2015) 293.
[3] M.F.M. de Groot et al., Phys. Rev. B 41 (1990) 928.
[4] M.F.M. de Groot et al., Phys. Rev. B 43 (1991) 6899.

103
Ⅲ-3-3

Ⅲ -3. Chemistry
BL3U
BL3U

Local Structure of Crown Ether Inclusion Complex in Water by Soft X-ray
Absorption Spectroscopy II. Interaction between Crown Ether-Ca2+
Complex and SCN- Anion
H. Yuzawa, M. Nagasaka and N. Kosugi

Institute for Molecular Science, Okazaki 444-8585, Japanenergy shift of C K-edge XAS.

Intensity / arb. units

(a)

(b)

Intensity / arb. units

399 399.5 400
Photon Energy / eV
Intensity / arb. units

Ⅲ-3

It is shown in Part I that the Ca L-edge XAS spectraof Ca(SCN)2-crown ether solutions can give theinformation about the coordination symmetry of crownether-Ca2+ inclusion complexes [1]. In this Part II, weshow C K-edge and N K-edge XAS spectra for SCNanion to investigate the interaction between crownether-Ca2+ inclusion complex and SCN- anion.
The experiments were carried out at BL3U. The
procedure of the XAS measurement is the same as thatin Part I [1]. Another aqueous solution (Ca(SCN)2 :H2O : EtOH = 1 : 59 : 3) was also prepared. In N K-edge
XAS, a liquid cell composed of two SiC membranes
instead of Si3N4 was used. The photon energy wascalibrated by using C K-edge and N K-edge XAS
spectra of the proline thin layer.
Figure 1 (a) shows the obtained N K-edge XAS spectra.
The absorption peak around 399.5 eV is assigned to the
1s → π* excitation of SCN- anion, whose peak top
energy is constant regardless of the addition of thecrown ethers. In the previous report of KSCN aggregate
structure in aqueous solution, the N atom in SCNinteracts with K+ and the N K-edge peak top energy isshifted to the lower energy than that of hydrated SCN[2]. Thus, the constant absorption peak energy for the
Ca(SCN)-crown ether solutions would be because N
atom in SCN- is apart from crown ether-Ca2+ complex.
Figures 1 (b) and (c) show C K-edge XAS spectra.
The obtained peak around 287.3 eV is assigned to the
1s → π* excitation of SCN- anion. The peak energy isshifted to the lower energy (Fig. 1 (b), orange, green
and blue lines) compared with that in the simple
aqueous Ca(SCN)2 solution (red line), while in the caseof aqueous Ca(SCN)2-EtOH solution, the energy shift
is not observed (Fig. 1 (c), gray line). This indicatesthat crown ether-Ca2+ inclusion complex and SCNanion are not completely dissociated and are interactedwith each other. However, in the case of KSCN
aqueous solution, the peak energy of C K-edge XAS in
SCN- is constant without relation to the formation of
aggregate structures, which means that the C atom in
SCN- hardly interacts with cations [2]. Furthermore,peak energy shift is not induced by EtOH without thecoordination to Ca2+ (Fig. 1 (c), grey line). Thus, theobtained energy shift would arise from the interaction
between the C atom in SCN- and crown ether ligand.
Therefore, the interaction between crown ether-Ca2+
inclusion complex and SCN- is expected as follows.
The coordination of crown ether to Ca2+ induces theinteraction between Ca2+ and SCN- from the S atom
direction. In this structure, the C atom is close to(interacted with) the crown ether ligand to induce the287 287.5
Photon Energy / eV(c)

287 287.5
Photon Energy / eV

Fig. 1. (a) N K-edge XAS spectra of aqueous
Ca(SCN)2 solution (red line), that containing 18crown-6 (orange line), that containing 15-crown-5(green line) and that containing 12-crown-4 (blue line),(b) C K-edge XAS spectra for the same solutions as
those of (a) and (c) C K-edge XAS of aqueous
Ca(SCN)2 solution (red line) and that containing EtOH
(gray line). The deviation in higher energy region (>287.5 eV) between red line and gray line is derived
from the absorption of EtOH.
[1] H. Yuzawa, M. Nagasaka and N. Kosugi, UVSOR
Activity Report in this volume.
[2] H. Yuzawa, M. Nagasaka and N. Kosugi, UVSOR
Activity Report 42 (2015) 97.

104
Ⅲ-3-4

Ⅲ -3. Chemistry
BL3U
BL3U

Study of Salting Effects in Compounds with Atmospheric Relevance byUsing Soft X-ray Absorption Spectroscopy
G. Michailoudi1, M. Patanen1, N. Prisle1, M. Huttula1, H. Yuzawa2, M. Nagasaka2 and N. Kosugi2
Nano and Molecular Systems research unit, University of Oulu, P.O. Box 3000, 90014 University of Oulu, Finland
2
UVSOR Synchrotron, Institute for Molecular Science, Okazaki 444-8585, Japan1

The aerosol particles in the atmosphere have an
important effect on climate. Previous studies revealed
the great impact of interactions between organic andinorganic compounds on atmospheric chemistry [1, 2].
In order to study salting effects on atmospheric organics,
soft X-ray absorption spectroscopy was applied. Thismethod has the advantage of high sensitivity to thechemical environment of the absorbing atom andtogether with molecular dynamics / quantum mechanics
modelling our aim is to learn i) what are the structuresof the formed hydrates of these organics ii) what are therelative concentrations of hydrated forms iii) how
addition of salts changes the relative abundance of thehydrates and does e.g. ion-pairing or complex formation
occur.
Aqueous solutions of organic compounds glyoxal(C2H2O2), methylglyoxal (C3H4O2), and glycerol(C3H8O3) were prepared in the chemistry laboratory rightbefore the experiments, in different concentrations,
ranging from 0.1 to 2 M. These compounds were also
mixed with sodium chloride (NaCl) or sodium sulfate(Na2SO4), with different mixing ratios, while theconcentrations of salts were 1 and 2 M. The samples wereplaced to a liquid flow cell [3] and exposed to soft X-ray
radiation at BL3U beamline at UVSOR synchrotron. In
order to investigate the carbon K-edge absorption spectra,
the photon energy was scanned between 280 and 305 eV,and for the oxygen K-edge absorption spectra, the chosenphoton energy range was from 525 to 550 eV.
Figure 1 presents examples of the preliminary
analysed data at the C 1s absorption edge of binary
glyoxal - water and methyl glyoxal – water solutions(black and red circles, respectively) together with
Na2SO4 addition. A background spectrum containing
absorption from water and liquid cell membranes has
been subtracted. The addition of salt does not introduce
shifts to the observed absorption features and it can beconcluded that in case of glyoxal, the bihydrated form isdominating. Methyl glyoxal shows three distinct
absorption features which can be associated with its
three inequivalent carbons.
Figure 2 shows a comparison of 2 M glyoxal solution(purple), 2 M Na2SO4 solution (green) and their mixture(red), together with a water spectrum (dashed blue line).
The spectra have been normalized to the backgroundpreceding the water pre-peak. The pre-peak shifts upon
addition of Na2SO4, which is evident from pure Na2SO4
aqueous solution. Modelling is needed to further
conclude about the aqueous forms of the studiedorganics.
The obtained data will give valuable information of

bulk properties of these solutions, as in larger
framework we are interested in the interactions
occurring in clusters and aerosols containing thesecompounds, their physical and chemical properties andtheir reactivity. Our goal is to access the missing
molecular scale information of aerosol particles and tobetter understand their impact on climate.

Ⅲ-3

Fig. 1. C K-edge spectra of glyoxal – water (2 M) andmethyl glyoxal - water (1 M) binary solutions and 1 :1 mixtures with Na2SO4.

Fig. 2. A comparison of 2 M aqueous solution ofglyoxal, 2 M Na2SO4 solution and their mixture,
together with a water spectrum.
[1] T. Kurtén et al., J. Phys. Chem. A 119 (2015) 4509.
[2] A.M.K. Hansen et al., Atmos. Chem. Phys. 15 (2015)
14071.
[3] M. Nagasaka, T. Hatsui, T. Horigome, Y. Hamamura
and N. Kosugi, J. Electr. Spectrosc. Rel. Phen. 177 (2010)
130.

105
Ⅲ-3-5

Ⅲ -3. Chemistry
BL3U
BL3U

Development of a Microfluidic Cell for Soft X-ray Absorption Spectroscopy
M. Nagasaka1, H. Fischer2, 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

Ⅲ-3

Microfluidics is a chemical technique to realize
highly efficient chemical reactions in liquids andsolutions [1]. Recently, X-ray diffraction in the hard Xray region has been used for a variety of systems byusing microfluidics [2]. However, it is difficult to apply
spectroscopic techniques in the soft X-ray region since
soft X-rays cannot penetrate a microfluidic cell. In thisstudy, we have successfully measured fluorescence
excitation spectra resembling soft X-ray absorption
spectroscopy (XAS) of structured liquids by developing
a microfluidic cell with a 100 nm thick SiC membrane
window.
The experiments were performed at BL3U
connected to a developed microfluidic cell. A T-shape
microfluidics setup with the width of 50 μm is madefrom PDMS resin which is covered by a 100 nm thick
SiC membrane. The adhesion of PDMS to the SiC
membrane is realized by pressing a Si frame of themembrane with O-rings. Pyridine and water are mixed
in the T-shape microfluidics cell with flow rate of 10
μL/min by using syringe pumps. The microfluidic cellis placed in a helium in atmosphere. The ultrahighvacuum of the soft X-ray beamline is separated fromthe microfluidic cell by a 100 nm thick SiC membranewith a window size of 36 × 23 μm2, which determines
the soft X-ray beam size. Spatially resolved XAS
spectra of microfluidic cell are measured in the
fluorescence mode by using a silicon drift detector.
Figure 1 shows a soft X-ray fluorescence image of
the T-shape microfluidic cell excited by soft X-rays at
550 eV. The fluorescence image shows high intensity
due to water, since the excitation energy of 550 eV isabove the O K-edge. Water flows from the upper side,and pyridine from the lower side. The water-pyridine
mixture flows to the right hand part after the junctionof the liquids. Figure 2 shows N K-edge XAS spectraof microfluidic cell at different positions. The N 1s →π* peak of pyridine in the mixed position (X=350,
Y=200) shows a shift to higher photon energy than isobserved for pure pyridine at X=200, Y=100. Theenergy shift of the pyridine-water mixture is consistent
with our previous XAS studies [3], in which theformation of a hydrogen bond of the N atom inpyridine with water causes a shift to higher photon
energy of the π* peak.
We have successfully measured spatially resolved
XAS of microfluidics in the soft X-ray regime with aspatial resolution of 36 × 23 μm2. In the future, we will
investigate several chemical reactions occurring in
microfluidic cell by spatially resolved XAS using our
T-shape microfluidics setup.

Fig. 1. Soft X-ray fluorescence image of a T-shape
microfluidic cell excited by soft X-rays at 550 eV. The
flows of pyridine and water are mixed in this device. It
also shows two spots to measure N K-edge XAS
spectra, as shown in Fig. 2.

Fig. 2. N K-edge XAS spectra at different positions in
the T-shaped microfluidic cell at positions indicated inFig. 1.
[1] T. Kitamori et al., Anal. Chem. 76 (2004) 53.
[2] B. Weinhausen and S. Köster, Lab Chip 13 (2013)212.
[3] M. Nagasaka et al., J. Electron Spectrosc. Relat.
Phenom. 200 (2015) 293.

106
Ⅲ-3-6

Ⅲ -3. Chemistry
BL4U
BL4U

Characterization of Macroporous Monolithic Polymers Containing
Amphiphilic Macro-RAFT Agent by Scanning Transmission X-Ray
Microscopy (STXM)
D. Arrua1, A. Khodabandeh2, T. Ohigashi3, N. Kosugi3 and E. Hilder1

Future Industries Institute, University of South Australia, Building X, Mawson Lakes Campus, GPO Box 2471
Adelaide SA 5001, Australia
2Australian Centre for Research on Separation Science (ACROSS), School of Chemistry, University of Tasmania,
Private Bag 75, Hobart 7001, Australia
3
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
1

Macroporous polymer materials with interconnectedstructures represent a useful class of polymers used indifferent fields including separation science in the last
decades [1]. An increasingly exploited method for the
preparation of highly porous scaffolds is based on thesolidification of the continuous phase of a high internal
phase emulsion (HIPE) through polymerization. A
cellular monolithic structure, commonly withinterconnected pores and hence an open cellular network
is produced, referred to as a poly(HIPE). Our aim here
is to develop a surfactant-assisted functionalization
strategy for preparation of styrene-based porous
polymers by HIPE polymerization, whereby theobtained porous polymers have a specific application[2]. An accurate characterization of such polyHIPE
material is needed to better understand the polymer
morphology as well as surface chemistry [3].
The characterization by STXM of polyHIPE
materials was performed at the BL4U beamline of the
UVSOR synchrotron radiation facility. STXM imaging
was conducted by focusing on the C 1s core-line signal
in NEXAFS. Fig. 1 shows the C 1s NEXAFS spectra
obtained for both polyHIPEs (A1 with macro-RAFT
agent and A2 with End-group removed macro-RAFT
agent) cross-linked styrene network.
The components found by STXM were thepoly(Sty-co-DVB) polyHIPE, the macro-RAFT
agent, and the embedding resin. The spectrum for the
crosslinked styrene-based scaffold has a strong peakat 284.6 eV, which is characteristic of C 1s → π*C=Ctransition in a phenyl ring. The macro-RAFT agent
spectrum shows two peaks: a strong peak at 284.9 eV,
which corresponds to the C 1s → π*C=C transition of
the phenyl ring (styrene of macro-RAFT agent) and apeak at 288.9 eV, which is characteristic of C 1s →π*C=O transition in esters. Using a sequence ofhighly resolved X-ray photon energies covering the C
1s spectral region (280 to 320 eV), successive image
was obtained for polyHIPE A2. STXM composite
component map on polyHIPE respect to thecorresponding X-ray spectra of references, themacro-RAFT agent, Styrene-DVB crosslinked
polymer network and epoxy components are shownin blue, green, and red, respectively in Fig. 2.
As a conclusion, soft X-ray microscopy images
recorded at multiple wavelengths have been used toqualify the chemical composition in polyHIPE. The
results shown in this work clearly demonstrate how
STXM analysis can reveal chemical information forthese materials.

Ⅲ-3

Fig. 1. NEXAFS reference spectra of the epoxy(embedding matrix), RAFT agent, macro-RAFT
agent, and polystyrene cross-linked polyHIPEs that
correspond to 1 nm thickness of each component.

Fig. 2. STXM color coded composite map (red=epoxy,green=PSty, blue=macro-RAFT agent).
[1] D. Wu et al., Chem. Rev. 112 (2012) 3959.
[2] A. Khodabandeh et al., Poly Chem 7 (2016) 1803.
[3] D. Arrua et al., UVSOR Activity Reports 42 (2014)
76.

107
Ⅲ-3-7

Ⅲ -3. Chemistry
BL4U
BL4U

Liquid-Liquid Interface between Triethylamine and Water Phases Studied
by Spatially-Resolved Soft X-ray Absorption Spectroscopy
M. Nagasaka, T. Ohigashi, H. Yuzawa, Y. Inagaki and N. Kosugi
Institute for Molecular Science, Okazaki 444-8585, Japan

Ⅲ-3

Aqueous triethylamine (TEA) solution shows alower critical solution temperature (LCST) behavior[1], in which two liquids are mixed at the lower
temperature and splits into two phases with thetemperature increase. Because the phase transition iscontrary to normal, the mechanism of LCST has not
yet been fully understood. In this study, we haveinvestigated local structures of liquid-liquid interfaces
between TEA and water phases by spatially-resolved
soft X-ray absorption spectroscopy (XAS).
The experiments were performed using a liquid flow
cell in STXM (scanning transmission X-ray microscope)on BL4U [2]. The liquid layer is sandwiched between 100
nm-thick Si3N4 membranes. The liquid-liquid interface
between TEA and water phases is formed from aqueous
TEA solutions with the molar fraction of 0.4 at thetemperature of 29.9 ºC, which is above the LCST.
Figure 1 shows O K-edge XAS of water at different
positions of the liquid-liquid interfaces. The inset shows
the soft X-ray transmission image at 530 eV, in which
the center part is a water phase and is surrounded by a
TEA phase. We have measured O and C K-edge XAS in
the region indicated by the red arrow. Figure 2 shows
molar concentrations of water and TEA at different
positions, which is determined from the edge-jumps of
XAS in O and C K-edges, respectively. In the TEA
phase, the molar fraction of TEA is increased to 0.6
because water molecules are gathered to the water phase.
It is consistent with the phase diagram of TEA-water
mixtures [1], where the LCST is increased at the higher
fraction of TEA. In the liquid-liquid interface, on theother hand, the amount of TEA is reduced to one third,
and that of water is drastically increased. In the waterphase, the most part is water molecules due to theformation of hydrogen bonding (HB) network of water.
Figure 3 shows the energy shifts of the pre-edge peaks(535 eV) in the O K-edge XAS at different positions. It isalready known that the pre-edge peak is shifted to thelower photon energy when HB between water molecules
is elongated. From the water to the TEA phase, the preedge peaks show lower energy shifts. Because the amountof water is decreased with the direction of the TEA phase,the hydrophobic interaction of ethyl group in TEA isstronger than the HB interaction of water, which leads tothe elongation of the HB network. Water and TEA
molecules are coexisted in the TEA phase because the HB
network of water is weakened. The liquid-liquid interface
between water and TEA phases is formed with thebalance of the hydrophobic interaction of TEA and HBinteraction of water, which is changed by gathering watermolecules to the water phase.

Fig. 1. O K-edge XAS of water at different positions.
The inset shows the image at 530 eV, in which the redarrows indicate the measurement region.

Fig. 2. Molar concentration of liquid-liquid interface
determined from the edge-jump of XAS.

Fig. 3. Peak shift of the pre-edge peak in O K-edge XAS
as a function of positions in the liquid-liquid interface.
[1] F. Kohler and O. K. Rice, J. Chem. Phys. 26 (1957)
1614.
[2] T. Ohigashi et al., AIP Conf. Proc. 1741 (2016)
050002.

108
Ⅲ-3-8

Ⅲ -3. Chemistry
BL4B
BL4B

Photoelectron-Auger Electron Coincidence Study of the Electron Emission
from Condensed Water Molecules
1

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, Japan
Electron coincidence spectroscopy enables one toclarify energy correlations between electrons emitted
after a single photon. Extremely-efficient electron
coincidence measurements can be achieved by a use of
the magnetic bottle technique [1]. In the present study,
photoelectron-Auger electron coincidence spectroscopyusing a magnetic bottle electron spectrometer is applied
to the study of inner-shell photoionization of watermolecules condensed on solid surface [2].
The experiment was performed at the beamline
BL4B under the single bunch operation of the storage
ring. Water molecules were adsorbed on the surface ofa copper wire, by continuously cooling the wire down
to the liquid nitrogen temperature, under the basepressure of ~1.8×10-8 Torr. Coincidence datasets wereaccumulated with a magnetic bottle electron
spectrometer [3], for electrons emitted from thecondensed water on irradiation of 738.2 eV photons.
The two-dimensional map in Fig. 1 displays theenergy correlation of the coincident electrons includedin the coincidence datasets. A clear structure running
vertically is associated with the coincidences between
the O1s photoelectrons and the Auger electrons fromcondensed water. To display the O1s photoelectron
structure closely, the coincidence counts on the map
are projected onto x-axis and are presented in the top
panel. The projection curve shows an O1s
photoelectron peak displaying a continuous structureon the lower kinetic energy side. The long tail is
attributed mainly to the photoelectrons with reduced
energies due to inelastic scatterings on the escape fromthe inside of the water condensation.
Figure 2 presents Auger electron spectra observed incoincidence with O1s photoelectrons (region (a) in Fig.
1) and energy-loss photoelectrons due to inelastic
scatterings (region (b) in Fig. 1). The coincidence Auger
spectrum in Fig. 2 (a) shows a considerable intensity
below 420 eV, which is ascribable to an energy loss of
the Auger electrons due to the inelastic scattering. In Fig.
2 (b), the contribution from the inelastic scattering isenhanced. This observation can be understood as
follows: the selection of photoelectrons with energy loss
picks out the photoemission events for H2O molecules
distant from the outermost surface and thus the Auger
electrons ejected from these molecules are also subject
to remarkable inelastic scattering.

Ⅲ-3

Fig. 1. Two-dimensional map showing the energy
correlation of the coincident electrons emitted fromcondensed water molecules on irradiation of 738.2 eV
photons.

Fig. 2. Auger electron spectra observed in coincidencewith O1s photoelectrons (region (a) in Fig. 1) andenergy-loss photoelectrons due to inelastic scatterings(region (b) in Fig. 1).
[1] J. H. D. Eland et al., Phys. Rev. Lett. 90 (2003) 053003.
[2] Y. Hikosaka et al., J. Electron Spectrosc. Rel. Phenom.
213 (2016) 17.
[3] Y. Hikosaka et al., J. Electron Spectrosc. Rel. Phenom.
192 (2014) 69.

109
Ⅲ-3-9

Ⅲ -3. Chemistry
BL6U
BL6U

Producing Mechanism of Metastable OCS3+ Studied by Photo-Electron-Ion
Coincidence Method
F. Kumaki1, H. Iwayama2, E. Shigemasa2 and K. Soejima1

Department of Environmental science, Niigata University Niigata 950-2181, Japan
2
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan1

Ⅲ-3

We have studied that dissociation processes andstabilities of molecules absorbed a soft X-ray which
are photo-ionized and subsequently lead to Auger
decay. While most multicharged molecular ionsproduced
after
photo-ionization
immediately
dissociate due to the Coulomb repulsion, the existenceof metastable multicharged molecular ions dependingon the electronic states is known. As a few exceptions,producing processes of the metastable multicharged
molecular ions are almost not clarified. The OCS
molecule is known to produce a doubly-ionizedmolecular ion. In the past work, we studied theprocesses of the producing metastable OCS2+ by an
Auger electron-photo ion coincidence technique. The
observation was done for Auger decay from C1s, O1s
and S2p inner shell photoionization. The valence
electronic configuration of the OCS is described as(6σ)2(7σ)2(8σ)2(9σ)2(2π)2(3π)2. This measurement
revealed that metastable OCS2+ can be produced whenits Auger final states with the (3π)-2 configuration. Alsoit was revealed that metastable OCS2+ produced
following S2p photoionization is populated with muchhigher possibility compared with that arising from C1s
and O1s photoionizations. It is understood that theorigin of this site-specificity in the production ofmetastable OCS2+ arises from the spacial distributionof 3π valence orbital involved [1, 2]. It is also known
that the metastable triply-ionized OCS molecule exists.
Does theproduction mechanism of the metastable
OCS3+ have characters like that of metastable OCS2+ ?
In this work, we have studied metastable OCS3+ by thephotoelectron-photoion coincidence measuremens.
The experiment was performed at the beamline 6U of
the UVSOR facility. We used the electron-ion
coincidence spectrometer consisting of a double toroidal
electron analyzer and an ion time-of-flight (TOF)
analyzer [2]. We measured photoelectronphotoion
coincidence signals following C1s, O1s and S2p
photoionization.
Figure 1 shows TOF spectra of photoions arisingfrom Auger decay following C1s, O1s and S2p
photoionization respectively in coincidence with thephoto-electrons. The peaks of OCS3+ are commonly
observed around 2500 ns though these are weak. The
ratio of the coincidence counts of C1s, O1s and S2p
photoionization is C1s:O1s:S2p = 2.8:1:1.9. The ratio
in metastable OCS2+ is S2p > O1s > C1s in the pastexperiment. The result of OCS3+ is different from that.
This indicates the existence of site-specificity in the
production metastable OCS3+ different from that in the

production of metastable OCS2+. In the future
experiment, we will observe using an Auger electron photoion coincidence method.

(a)

(b)

(c)

Fig. 1. TOF spectra of ions produced by Auger decay
following C1s, O1s and S2p ionization in coincidencewith photo-electron. (a) C1s ionization (b) O1s
ionization (c) S2p ionization.
[1] T. Kaneyasu et al., J. Korean Phys. 54 (2009) 371.
[2] T. Kaneyasu et al., J. Phys. B: At. Mol.Opt. Phys. 48(2015) 125101.

110
Ⅲ-3-10

Ⅲ -3. Chemistry
BL6U
BL6U

F KVV and Xe M45N45N45 Auger Spectra of Xenon Difluoride
across the Xe 3d and F 1s Thresholds
F. Yamashita1, M. Kono2, 3, 4, H. Iwayama5, 6, K. Okada1 and E. Shigemasa5, 6

Department of Chemistry, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
2
Senri International School of Kwansei Gakuin, Minoh 562-0032, Japan3
School of Science and Technology, Kwansei Gakuin University, Sanda 669-1337, Japan
4
RSPE, Australian National University, Canberra, ACT 2601, Australia
5
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
6
School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
1

Xenon difluoride has been of great interest as anoble gas compound. The molecule intrigues X-ray
spectroscopists because it has similar binding energies
among Xe 3d5/2, Xe 3d3/2 and F 1s subshells [1].
Southworth et al. recently measured the partial ionyield curves of XeF2 and found that the charge state
distribution of Xeq+ shifts down compared to the Xeatom case [2]. This report focuses on the Auger
spectroscopy in order to get more insight into themolecular electronic states leading to the production of
Xeq+. Resonant and normal Auger spectra are acquired
as a function of photon energy in this study.
The experiments were performed on the soft X-ray
beamline, BL6U. A main chamber was equipped with agas cell and a high-resolution hemispherical electron
analyzer (MBS A-1). Sublimated XeF2 sample wasintroduced into the cell so as to keep the pressure in themain chamber at 7.5 × 10-4 Pa during the measurements.
The electron spectra were acquired over the photon
energy range of 668.9–709.9 eV. The energy resolutionsof incident photons and detected electrons were set at
0.7 and 0.48 eV, respectively.
Figure 1 shows typical resonant and normal Auger
spectra plotted on the electron kinetic energy scale.
The peaks labeled A–E can be assigned to the Augertransitions of F KVoVo, F KViVo, F KViVi, Xe
M4N45N45 and Xe M5N45N45, respectively, referring to
the Auger spectra of Xe [3] and F2 [4]. Here thesymbols Vo and Vi represent outer- and inner-valenceorbitals, respectively. The photon energy of 682.9 eVcorresponds to the resonance transition from Xe 3d3/2
and/or F 1s to the σ* orbital. Figure 1 reveals that theAuger band A is most intense at this resonance,
indicating that the F 1s excitation is dominant andthereby suggesting that the Auger final states have twoholes in the Vo orbital(s) plus an electron in the σ*
orbital. This is consistent with the study by Southworth
et al., reporting the specific increase in the Xe+ and F+
ion yields at the σ* resonance [2]. At the photon energyof 686.7 eV, on the other hand, which is assigned to theshape resonance, Xe 3d5/2-1ϵf, the Auger band E (Xe
M5N45N45) is predominantly observed. This transition
is followed by the cascade Auger processes where
ionization repeats until the holes are left in the valenceorbitals. The occurrence of these processes is consistent
with the fact that the branching ratios of multi-charged

Xe2+, Xe3+ and Xe4+ ions increase [2]. Our results
illustrate that a strong correlation exists between theAuger transitions and fragmentation channels. We havea plan to carry out the Auger-electron–photoion
coincidence (AEPICO) measurements to justify thisdirectly and the results will be published in the near
future.

Ⅲ-3

Fig. 1. Resonant and normal Auger spectra of xenon
difluoride. A, F KVoVo; B and Bʹ, F KViVo; C, F
KViVi; D, Xe M4N45N45; and E, Xe M5N45N45. The
dotted lines show the peak correspondence for the Xe
4p and 4d photoelectrons.
[1] T. X. Carroll, R. W. Shaw Jr., T. D. Thomas, C. Kindle
and N. Bartlett, J. Am. Chem. Soc. 96 (1974) 1989.
[2] S. H. Southworth, R. Wehlitz, A. Picón, C. S.
Lehmann, L. Cheng and J. F. Stanton, J. Chem. Phys. 142(2015) 224302.
[3] L. O. Werme, T. Bergmark and K. Siegbahn, Phys.
Scr. 6 (1972) 141.
[4] P. Weightman, T. D. Thomas and D. R. Jennison, J.
Chem. Phys. 78 (1983) 1652.

111
Ⅲ-3-11

Ⅲ -3. Chemistry
BL6U
BL6U

Formation of H2+ Fragments in Dissociation of Methanol Dication
M. Higuchi1, K. Soejima1, 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

Ⅲ-3

When a molecule absorbs a soft x-ray photon, innershell photoionization emitting a photoelectron are
induced and then Auger decay emitting an Auger
electron follows. Because two electrons are emitted
through this process, the molecule with two positive
charges, or molecular dication, is produced. The
dication dissociates into ion pairs due to the Coulomb
repulsion between the two positive charges. In thisstudy, we have investigated the dissociation fragmentsfrom dication states formed after the inner-shell
photoionization and the Auger decay process of
methanol molecules.
The experiment was performed in the undulator
beamline BL6U at the UVSOR facility. We used anelectron-ion coincidence spectrometer composed of a
toroidal electron analyzer and an ion momentum
imaging analyzer.
In this report, we focus on the formation ofmolecular hydrogen ion from dication states inmethanol molecule. Fig. 1 shows time-of-flight spectraof light fragment ions produced after the C1s innershell ionization of CH3OH (black), CD3OD (green),
CH3OD (red) and CD3OH (blue). In the three panels,
the spectra for the individual deuterated methanol
molecules are compared with the one for CH3OH. The
formation of H2+ fragments is observed in the CH3OH
spectrum, where the fragments can be produced fromtwo hydrogen atoms originally bonded to the C atom,or from one hydrogen atom at the C side and thehydrogen atom at the O side. The intensity of D2+ in
the CD3OD spectrum is about the half of H2+ in the
CH3OH spectrum, which manifests that deuteration
reduces the formation of molecular hydrogen ion fromthe dication states.
When only the hydrogen atom at the O side is
deuterated (i.e., for CH3OD), the HD+ formation, as
well as the intense H2+ peak, is weakly observed. Thisobservation implies that, while the molecularhydrogen ions are mainly from the hydrogen atoms at
the C side, a fraction of the molecular hydrogen ions is
produced from one hydrogen atom at the C side andthe hydrogen atom at the O side. On the other hand,formation of HD+ is hardly identified in the CD3OH
spectrum; the HD+ formation using the hydrogenatoms at both sides is reduced by the deuteration at theC side. This finding suggests that the hydrogenmigration forming HD+ is mainly from the C side to
the O side, and the migration is discouraged by the
deuterium of hydrogen atoms at the C side.

Fig. 1. Time-of-flight spectra for CD3OD (green),
CH3OD (red) and CD3OH (blue), compared with thetime-of-flight spectrum for CH3OH (black).

112
Ⅲ-3-12

Ⅲ -3. Chemistry
BL6U
BL6U

Dissociation Dynamics of Dication States in Water Molecules
F. Kumaki1, K. Soejima1, 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 absorbed a soft X-ray photon may lead toinner shell ionization and subsequently to Auger decay.
Emission of two electrons through this sequential
process results in the production of a doubly-ionizedmolecule. The doubly-ionized molecule called dicationis unstable because of the Coulomb repulsion of twoplus charge in the molecule, and often becomesfragmentation into ion pairs. In this work, we havestudied the dissociation processes of dication states inwater molecules by an electron-ion coincidence method.
The experiment was performed at the beamline 6Uof the UVSOR facility. We used the electron-ion
coincidence spectrometer consisting of a double
toroidal electron analyzer and an ion time-of-flight(TOF) analyzer [1]. We measured Auger electron-ion
coincidences for the gas-phase H2O, D2O and HDO tounderstand the deuteration effect in the dissociationsof the dication states.
The black curves in Fig. 1 are the Auger spectra of
H2O and D2O, which show band structures. The
coincidence Auger spectra filtered for the two-bodyfragmentations into H++OH+ or D++OD+ are
represented in red, and those filtered for the three-bodyfragmentations into H++O++H or D++O++D are in blue.
The peaks of the two-body fragmentations and threebody fragmentations are commonly observed around
41eV and 45eV, respectively. In both H2O and D2O, thetwo-body dissociation is preferred to the three-bodydissociation. The ratios of the coincidence counts forthe two-body and the three-body dissociations are
1.9:1 for H2O and 3.1:1 for D2O; the contribution fromthe three-body dissociation is higher in H2O than in
D2O [2].
Figure 2 shows the two-dimensional TOF map of
ion pairs formed after the Auger decay in HDO,
observed in coincidence with Auger electrons in thewhole energy range. Two structures indicated bycircles correspond to two-body dissociations of
HDO2+→H+-OD+ and HDO2+→D+-OH+. The intensity
ratio of the two dissociations is estimated, from thecoincidence counts in the map, to be H+-OD+ : D+-OH+= 2.3:1. The elongation of the D-O bond takes longer
in time than that of the H-O bond because of theheavier hydrogen atom, which may results in thefavorable dissociation of the H-O bond.

(a)

(b)

Ⅲ-3

Fig. 1. Total Auger spectra (black) and coincidence
Auger spectra filtered for the two-body dissociation(red) and for the three-body dissociation (blue) in (a)H2O and (b) D2O [2].

Fig. 2. Two-dimensional TOF map of ion pairs
following HDO Auger decay observed in coincidencewith Auger electrons in the whole energy range.
[1] T. Kaneyasu et al., J. Phys. B: At. Mol. Opt. Phys. 48(2015) 125101.
[2] M. Kikuchi et al., UVSOR Act. Rep. 43 (2016) 106.

113
Ⅲ-3-13

Ⅲ -3. Chemistry
BL6U
BL6U

Chemical Shift of Inner-Shell Binding Energies in Primary Bromoalkanes
H. Fujise1, 2, H. Iwayama1, 2 and E. Shigemasa1, 2Institute 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

Molecular inner-shell electrons do not play significant
roles in forming chemical bonds, however, studies
suggest that there are differences in the inner-shellbinding energy for an atom of certain elements,
depending on the chemical environments of the probed
atom. This is called a “chemical shift”. Remarkablechemical shifts of inner-shell binding energies of the
carbon 1s electron in four different bonding environmentsof ethyl trifluoroacetate have been successfully
demonstrated by Siegbahn [1]. To elucidate the molecularsize effects of these chemical shifts on inner-shellionization energies and binding energies of Auger final
states, we have measured the Br 3d photoelectrons andMVV (V = valence level) Auger electrons produced after
inner-shell photoionization in primary bromoalkanes.
The experiment was conducted on the soft X-ray
beamline BL6U at UVSOR. The radiation from theundulator was monochromatized by a variable included
angle varied line-spacing plane grating monochromator.
The monochromatized light was introduced into a gas callwith the sample gas mixture (CH3(CH2)nBr (n = 0 - 6):90%, Kr: 10%). The photon energies for 3d photoelectron
and Auger electron measurements were set to 200 eV, and88 eV, respectively. The kinetic energies of the emitted
electrons were measured by a hemispherical electronenergy analyzer (MBS-A1), at a magic angle of 54.7°
from the polarization vector. The resolution of the kinetic
energy depends on the pass energy of the electrons in thehemisphere, and the width of the entrance slit of theanalyzer, which were set to ~30 meV and ~6 meV, at passenergies 50 and 10 eV, respectively, at a slit width of 0.2
mm. The kinetic energy scales were calibrated with the
3d and 4s photoelectrons of Kr atoms in the sample gas
mixture, for 3d photoelectron and Auger electron
measurements, respectively.
The Br 3d photoelectron spectra of CH3(CH2)nBr (n =0 - 6) are shown in Fig. 1. Two broad structures observed
for all n, are assignable to the Br 3d3/2 and 3d5/2
components. In practice, it is known that the broad
structures are attributed to the total of five ligand field
splitting peaks [2], furthermore, there were no differences
observed between the position of the ligand-field splitting
components and molecular size. The broad structures
shift to the lower binding energy side, as the molecularsize increases. These chemical shifts imply that the charge
distribution of bromoalkanes are different in size, andmay be attributed to factors such as the different
electronegativities of larger ligands. The Auger spectra
for CH3Br and C7H15Br are shown in Fig. 2. The peak
profile of the spectra become more complex as thenumber of carbon atoms increase in the alkane chain, andthe kinetic energies shifts to the higher energy side. This
is attributed to the more complex molecular orbitals andelectronic structures involved in the MVV Auger process
observed.

Fig. 1. Photoelectron spectra of CH3(CH2)nBr (n = 0 6) measured at photon energies 200 eV.

Fig. 2. Auger spectra of CH3(CH2)nBr (n = 0 ~ 6)
measured at photon energies 88 eV.
[1] K. Siegbahn, Pure & Appl. Chem. 48 (1976) 77.
[2] J. Johnson et al., J. Phys. B: At. Mol. Opt. Phys. 30(1997) 4899.

114
Ⅲ-3-14

Ⅲ -3. Chemistry
BL6U
BL6U

Intermolecular Vibrational Relaxations of Core Excited Nitrogen Clusters
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, Japan2

The photoreaction of isolated molecules in the gas
phase is one of the most studied chemical reactions.
However, since most chemical reaction in nature takeplace in condensed matter such as solids and liquids, it
is important to understand intermolecular processes.
Photodissociation of molecules in condensed matter
would be quite different from that of isolated molecules,
since energy and charge transfers into neighboring
molecules may suppress molecular dissociation. Massmeasurements of fragment ions in condensed matter aredesirable, but it is difficult to extract them from solids or
liquids. On the other hand, molecules in clusters have asimilar environment to condensed matter, and theirfragments can be easily measured as well as isolated
molecules. In this work, we performed Auger-electronion coincidence measurements for isolated nitrogen andclustered nitrogen and investigated intermolecular
processes of core excited nitrogen clusters.
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 for isolated and clustered nitrogen[1].
Nitrogen clusters were produced by supersonic
expansion through a 100-μm nozzle at 110 K. The
average cluster size was estimated to be ~300
molecules per cluster.
Figure 1 shows time-of-flight mass spectra for (a)molecular nitrogen and (b)clustered nitrogen. For
molecular nitrogen, we observed parent molecular ionsof N2+ and fragment ions of N+. For clustered nitrogen,we observed (N2)n+ (n≧1) and (N2)nN+ (n≧0). In thepresent condition, the abundance of N+ ions from core
excited nitrogen clusters was negligibly small.
Figure 2 shows the coincidence Auger spectra for(a)isolated and (b)clustered nitrogen. Most N2
molecules dissociate into N+ fragment ions above 23.4
eV, which is corresponds to the lowest dissociation
limit of N2+. This is because isolated molecules canrelease the excess energy only by radiative decays,
whose time scales are nanoseconds, much slower thanthat of the dissociation process. On the other hand, forclustered nitrogen, we observed significant amount of
N2+ ions well above the N2+ dissociation limit. This
may suggest that intermolecular process, such as,vibrational relaxations suppress molecular dissociation.
Analysis in more detail is in progress.

Ⅲ-3

Fig. 1. Time-of-flight mass spectra for (a) N2 moleculesand (b) clusters. For nitrogen clusters, we subtracted
contributions of molecular nitrogen in the cluster beam.

Fig. 2. Coincidence Auger spectra for (a)N2 molecules
and. (b)clusters. For nitrogen clusters, we subtracted
contributions of molecular nitrogen in the cluster beam.
Black bars represents the lowest dissociation limit of N2+.
[1] R. Flesch et al., Phys. Rev. Lett. 86 (2001) 3767.

115
Ⅲ-3-15

Ⅲ -3. Chemistry
BL6B
BL6B

Infrared Microscopy of Pyridine-Water Mixtures in T-Shape Microfluidics
M. Nagasaka1, H. Fischer2, H. Yuzawa1, M. Nakano1, N. Takada1, M. Aoyama1, E. Rühl2
and N. Kosugi1
Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
Physikalische Chemie, Freie Universität Berlin, Takustr. 3, D-14195 Berlin, Germany
1

2

Ⅲ-3

Microfluidics is a chemical technique to realize
highly efficient chemical reactions in liquids andsolutions [1]. Recently, X-ray diffraction in the hard Xray region has been used for a variety of systems byusing microfluidics [2]. On the other hand, we havedeveloped a microfluidic system for soft X-ray
absorption spectroscopy (XAS) [3]. In this study, we
have used it for infrared (IR) microscopy.
The experiments were performed by using the IR
microscopy setup IRT-7000 at UVSOR BL6B. A Tshape microfluidics setup with the width of 50 μm is
made from PDMS resin which is covered by a 100 nm
thick Si3N4 membrane. Pyridine and water are mixed
in the T-shape microfluidic cell with a flow rate of 20
μL/min by using syringe pumps. The spatial resolutionof 30 × 30 μm2 is reached by using a ×16 Cassegrain
mirror. IR spectra are taken by detecting the reflected
infrared light with an MCT detector.
Figure 1(a) shows an optical microscopic image of
the T-shape microfluidic cell. Water and pyridine areflowed in the left and right hand parts, respectively. We
have found a laminar flow, in which pyridine and water
are separately flowed at the center of the mixing region
behind the junction of the liquids. Figure 1(b) shows
IR spectra of pyridine and water taken from themicrofluidic system. The IR spectra show the OH
stretching vibration of water at 3507 cm-1 and the CH
stretching vibration of the pyridine ring around 3100
cm-1, respectively. We have measured IR spectra witha spatial resolution of 30 × 30 μm2 in the same regionof the optical image shown in Fig. 1(a). The
absorbance of pyridine and water at different positions
is obtained by fitting the IR spectra to the mentioned
vibrational peaks of pyridine and water.
Figure 1(c) shows the 2D image of the absorbanceof pyridine. The right hand part and the mixed regionof the T-shape microfluidic cell show high intensity ofpyridine. The left hand part of the laminar flow in themixed region, which is mainly filled with water, also
shows high intensity of pyridine. Because the spatial
resolution of the IR microscope (30 × 30 μm2) is larger
than the width of the pyridine part in the laminar flow
(25 μm), the water part in the laminar flow also showssome intensity of pyridine. Figure 1(d) shows a 2D
image of the absorbance of water. Unlike the pyridine
case, water shows high intensity outside themicrofluidic channel. This means that the adhesion of
the Si3N4 membrane to PDMS was insufficient in thewater part, which is unlike the pyridine part. Recently,
we have measured XAS of pyridine-water mixtures in

our T-shape microfluidic system, and confirmed theadhesion of SiC is sufficient even in the water part [3].
Note that the microfluidic cell is kept in a helium
atmosphere, where the pressure is several percent
higher than the ambient pressure. The adhesion of SiC
to PDMS is then strong enough because the SiC
membrane is pressed by the helium gas. In the future,
we will include this helium pressing system to themicrofluidic cell in order to take more reliable IR
microscopy images of T-shape microfluidics.

Fig. 1. (a) An optical microscopy image of the T-shape
microfluidic cell. A laminar flow is formed after mixing
the flows of pyridine and water. (b) IR spectroscopy of
pyridine and water taken from the positions of pyridine
and water in T-shape microfluidic cell. The 2D imagesof the absorbance of (c) pyridine and (d) water in the Tshape microfluidic cell are also shown.
[1] T. Kitamori et al., Anal. Chem. 76 (2004) 53.
[2] B. Weinhausen and S. Köster, Lab Chip 13 (2013)212.
[3] M. Nagasaka et al., in this volume.

116
Ⅲ-3-16UVSOR User 6

UVSOR User 7