Ⅲ-3
Chemistry
ChemistryⅢ -3. Chemistry

BL3U

Microfluidics of Liquid Mixtures for Soft X-ray Absorption Spectroscopy
M. Nagasaka1, 2, A. A. Vu1, 3, H. Yuzawa1, N. Takada1, M. Aoyama1, E. Rühl3 and N. Kosugi1, 2
2

1
Institute for Molecular Science, Okazaki 444-8585, JapanSOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan3
Physikalische Chemie, Freie Universität Berlin, Takustr. 3, D-14195 Berlin, Germany

Microfluidics is a chemical technique to realize
highly efficient chemical reactions in liquid phase [1].
Recently, X-ray diffraction in the hard X-ray region
has been used for a variety of systems by using
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.
Previously, we developed a microfluidic cell for soft
X-ray absorption spectroscopy (XAS) of structured
liquids [3]. In this study, we have successfully
observed a laminar flow between pyridine and waterin soft X-ray fluorescence image by improving a
microfluidic cell and measured N K-edge XAS in themixed part of microfluidics to reveal the interaction
between water and pyridine in a laminar flow.
The experiments were performed at the BL3U
connected to a custom-made microfluidic cell. A Tshape microfluidics setup with the width of 50 μm is
made from PDMS resin which is covered by a 100
nm Si3N4 membrane. Pyridine and water are mixed in
the microfluidics with flow rates of 4 μl/min by using
syringe pumps. The ultrahigh vacuum of the soft Xray beamline is separated from the microfluidic cellthat is kept at atmospheric helium pressure by a 100
nm thick SiC membrane with a window size of 30 ×
30 μm2. This window determines the photon beam
size [4]. Spatially resolved XAS spectra of the
microfluidic cell are measured in the fluorescence
yield mode at around 320 eV to 430 eV in N K-edge
and at 460 eV to 580 eV in O K-edge, respectively,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. Pyridine (P) flows from the upper side, andwater (W) from the lower side. The water-pyridine
mixture (M) flows to the right-hand part after thejunction of the liquids. Since 550 eV is above the O
K-edge, the fluorescence shows high intensity due towater and low intensity at pyridine, respectively. The
laminar flow of water and pyridine is observed in themixed part of the microfluidics.
Figure 2 shows N K-edge XAS spectra at different
positions in the mixed part shown in Fig. 1, where thehorizontal position is fixed to X = 600 μm and thevertical positions are scanned. From the intensity of
the N 1s → π* transition, the center position of themixed part is at Y = 504 μm. By changing theposition from pyridine (Y = 540 μm) to the water part
(Y = 460 μm), the π* peak shows a spectral shift tothe higher photon energy due to the formation of thepyridine-water mixtures [5]. This shift abruptly

occurs at Y = 500 μm, indicating clearly the phaseseparation in the laminar flow.

Ⅲ-3

Fig. 1. Soft X-ray fluorescence image of a T-shaped
microfluidic cell excited by soft X-rays at 550 eV. A
laminar flow is observed in the mixed part.

Fig. 2. N K-edge XAS spectra at different positionsin the mixed part of the microfluidic flow shown in
Fig. 1. The horizontal position is fixed to X = 600 μm,
and the vertical position is scanned in the mixed part.
[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., UVSOR Activity Report 2016(2017) 106.
[4] M. Nagasaka et al., J. Electron Spectrosc. Relat.
Phenom. 224 (2018) 93.
[5] M. Nagasaka et al., Z. Phys. Chem. in press.

1051 Ⅲ03-

Ⅲ -3. Chemistry
BL1U
BL1U

Molecular Orientation Induced by Irradiation UV to Achiral Dinuclear
Schiff Base Metal Complexes-PVA Hybrid Materials
T. Akitsu1, H. Nakatori 1, S. Yagi1, H. Sato1, T. Soejima1, S. Yamazaki1,
D. Tadokoro2, M. Fujiki3, M. Fujimoto4 and M. Katoh4

Faculty of Sciences, Tokyo University of Science, Tokyo 162-8601, Japan
Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
3
Graduate School of Materials Sciences, NAIST, Nara 630-0192, Japan
4
UVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
1

2

Ⅲ-3

In recent years, studies on optical vortex light haveattracted attention. A light vortex having a spiralwavefront and carrying an orbital angular momentum
gives a torque when irradiated on an object. As aresult, a phenomenon which cannot be observed withordinary light is expected. In fact, applied research on
azo polymers has been reported.
We have attempted molecular orientation control
by irradiating linearly and circularly polarized
ultraviolet light to a polymer film in which an azodye that undergoes a photoisomerization reaction
with a Schiff base metal complex is dispersed [1].
Previous research has revealed that it aligns in one
direction by irradiation with linearly polarized
ultraviolet light and spirally aligns by irradiation withcircularly polarized ultraviolet light. Herein, thepurpose of this research is to investigate what will
happen if light vortex is irradiated on the complex wehave studied so far.
We measured UV-vis spectra of MO (methyl
orange, azo-dye), ZnL (Fig. 1), ZnL+MO in PVA(polyvinyl alcohol) aqueous solution. An absorption
peak was observed in the vicinity of 280 nm in all thesamples. Therefore, the irradiation wavelength of the
optical vortex was set to 280 nm. Photo-illumination(both circularly polarized light and optical vortex) of
UV light was carried out using UVSOR BL1U.
Prior to actual experiments, we have investigatedonly PVA films to remove effects of artifact CD
peaks due to LD of oriented samples. Difference CD
spectra PVA films before and after optical vortex(270 nm, l=-1, 1) irradiation corresponding to the ππ* band of acetate groups were carefully confirmed
to disappear artifact CD peaks just like Fig. 2.

(due to Weigert effect) but also only ZnL (due toorbital angular momentum) could be successfully
observed to appear CD peaks after optical vortex
irradiation.

Fig. 2. CD spectra 0°, 45°, 90° reverse side of PVA
cast film after optical vortex (280 nm, l=-1)
irradiation.

Fig. 3. CD spectra 0°, 45°, 90° reverse side of PVA
cast film containing ZnL+MO after optical vortex(280 nm, l=-1) irradiation.

Fig. 4. CD spectra 0°, 45°, 90° reverse side of PVA
cast film containing ZnL after optical vortex (280 nm,l=-1) irradiation.
Fig. 1. Crystal structure of ZnL from PXRD data.
As shown in Figs. 3 and 4, not only ZnL+MO[1] N. Sunaga, T. Akitsu, T. Konomi and M. Katoh,
MATEC Web of Conferences 130 (2017) 07004.

1062 Ⅲ03-

Ⅲ -3. Chemistry
BL3U, BL4U
BL3U, BL4UXAS Characterizations on NaOH Solutions and Calcium Chlorides inTransmission Mode
Y.-S. Liu1, P.-A. Glans1, J. Guo1, M. Nagasaka2, T. Ohigashi2 and N. Kosugi2
1

Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
2
Institute for Molecular Science, Okazaki 444-8585, JapanThe electronic structure of ion solvated in liquids
has long been studied owing to its importance inmany applications. The related ionic and electronictransportation mechanisms are still far fromunderstood in the microscopic scales, which are
crucial for the broad applications ranging frombioscience, pharmacology and energy science such as
metal ion batteries.
Here, we are reporting our preliminary results
taken at UVSOR in 2016 and 2017 on O K-edge
XAS in NaOH solutions and Ca L-edge in CaCl2
solutions in different solvents (water, methanol andethanol). The results show that the in-situ capabilities
are promising at UVSOR beamlines, especially intransmission mode really provide high quality XAS
spectra and stability.
Figure 1 left shows the O K-edge XAS that are
taken at UVSOR from the concentrated NaOH
solutions. The results are showing that the solvated
OH- anion group gives a spectroscopic signaturefeature at around 532 ~ 533 eV (see enlarged Fig.1
right). This feature has intensity change depending on
the concentration corresponding to the increasing of
OH- content in the solutions. Most importantly, theseresults are consistent with our previous experimental
study using fluorescence and electron-yield modemeasurements at the other synchrotron facilities. In
addition, the theoretical calculated XAS spectra of
NaOH solutions are to be completed forunderstanding the ion solvation shell. The results
taken at UVSOR could be extremely helpful as the
XAS spectra obtained from the transmission
geometry removes the so-called saturation effect,
which is often been questioned in fluorescence mode.
Figure 2 shows the Calcium L-edge spectra of 1
Molar CaCl2 in different solvents (water, methanol
and ethanol). The experimental Ca L-edges spectra
are extremely sensitive to its solvents. However,since Ca2+ has a 3d0 configuration, the pronounced
differences between solvents indicating that the polar
solvent, i.e. water vs. methanol, plays an importantrole to its electronic structure. The main differences
can be seen from the variation of pre-peak intensities
around 348.4 and 351.4 eV. However, the detailsolvation shells need to be confirmed and incorporate
with theoretical calculations.

Fig. 1. O K-edge XAS spectra
concentration NaOH solutions.

ofdifferent

Fig. 2. Ca L-edge XAS spectra in different solvents.

1073 Ⅲ03-

Ⅲ-3

Ⅲ -3. Chemistry
BL3U
BL3U

Soft X-ray Absorption Spectroscopy of 4-Cyano-4’-pentylbiphenyl
Molecules in Liquid, Liquid-crystal and Solid Phases
H. Iwayama1, 2

UVSOR Synchrotron 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

The liquid crystal is one of the most importantmaterials for display devices. In the case of nematic
liquid crystals, the rod-shaped organic molecules
have no position order, but they self-align to havelong-range directional order with their long axes
roughly parallel. Since X-ray absorption finestructure (XAFS) spectroscopy is sensitive to a local
atomic geometry and the chemical state of the atomof one specific element, XAFS spectroscopy issuitable to investigate structures of liquid crystals
materials. However, XAFS measurement of liquid
crystal materials is limited to one in a solid phase dueto the requirement of high vacuums of a sample
chamber. Considering the fact that they work as
display device in a liquid-crystal phase, we need tomeasure XAFS in a liquid-crystal phase. Recently,
Nagasaka developed a liquid cell [1], which allows us
to measure XAFS spectra of liquid samples. In thiswork, we measure XAFS of liquid-crystal materials
in liquid, liquid-crystal and solid phase with thisliquid cell.
Our sample is 4-Cyano-4’-pentylbiphenyl (5cb),
which is one of the most popular liquid-crystal
materials. A schematic draw of 5cb molecules is shownin Fig. 1. The phase transition temperature of liquid toliquid-crystal and liquid-crystal to solid are 22.5 and35C, respectively. The XAFS measurements werecarried out at BL3U. After liquid cell which iscomposed of two Si3N4 membranes was filled withthe liquid sample, the thickness of liquid sample was
optimized by controlling the He gas pressure aroundthe cell. The photon energy was calibrated by using theC-K edge XAS spectrum of the proline thin layer.
Figure 1 shows C K-edge XANES spectra of 5cb
sample at three different temperature, whichcorrespond to liquid, liquid-crystal and solid phases.
We observed a strong peak at 285 eV, whichcorrespond to a core excitation of C 1s to π* orbitalsof phenyl group. The peak intensities and shapes aredifferent for each phase. Figure 2 shows N K-edge
XANES spectra of 5cb molecules. Splitted peaks at
398.7 and 399.5 eV correspond to a core excitation of
N 1s to π* orbitals of nitrile group. As well as C Kedge XANES spectra, peak intensities of 1s-to-π*core excitation at N K-edge depend on their phases.
This phase dependence of core excitations reflect
the change of molecular alignments between eachphases. Our results shows XANES is powerful tool toobserve change of a local chemical environment. A
more detail analysis is now in progress.

Fig. 1. Schematicdraw
pentylbiphenl (5cb) molecules.

of

4=Cyano-4’-

Fig. 2. C K-edge XANES of 5cb molecules at 18(solid), 26 (liquid-crystal) and 39 C (liquid).

Fig. 3. N K-edge XANES spectra of 5cb samples at
18 (solid), 26 (liquid-crystal) and 39 C (liquid).
[1] M. Nagasaka, H. Yuzawa and N. Kosugi, J.
pectrosc. Relat. Phenom. 200 (2015) 293.

1084 Ⅲ03-

Ⅲ -3. Chemistry
BL3U
BL3U

Temperature Dependence of Interaction around NO2- in Aqueous KNO2
Solution by Soft X-ray Absorption Spectroscopy
2

H. Yuzawa1, M. Nagasaka1, 2 and N. Kosugi1, 2Institute for Molecular Science, Okazaki 444-8585, Japan
School of Physical Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8585,
Japan
1

Understanding of interactions in aqueous
electrolyte solutions is one of the highly attractive
research subjects [1]. Recently, our research grouphas studied the interaction between some cations andwater by using O K-edge soft X-ray absorption
spectroscopy (XAS) of water in the transmission
mode [2]. In the present study, we have investigated
the temperature dependence of the interaction aroundthe NO2- anion by N and O K-edge XAS.
XAS spectra were measured at BL3U equippedwith the liquid cell system in the transmission mode[3]. Aqueous KNO2 solution sample (Molar ratio is
KNO2 : H2O = 1 : 42.6) was prepared by using thecommercial reagent without further purification.
After the liquid cell which is composed of two Si3N4
membranes and Teflon spacer was filled with thesample, the thickness of the liquid cell was optimizedby controlling the He pressure around the cell and N
or O K-edge XAS was measured. Temperature in thecell (0 − 70°C) was controlled by the circulation of aliquid heat carrier by using a thermo-chiller, and it ismonitored by a thermopile. The photon energy wascalibrated by the spectrum of the thin polymer film.
Figure 1 shows N and O 1s → π* peaks of NO2- in
the aqueous KNO2 solution at various temperatures.
In both the N and O K-edges (Fig.1a, b), the shape ofthe observed peaks such as half width is not changed
by heating from 0 to 70°C. On the other hand, thepeak energy shift shows a different behavior to eachother. Fig. 2 shows the temperature dependence of theobserved peak top energy shift. In the N K-edge XAS,
the peak top energy is almost constant, indicating thatthe interaction around N atoms in NO2- is hardly
influenced by the investigated temperatures. In the O
K-edge XAS, the peak top energy is constant until
40°C, but shows a sudden shift to the lower energy
with increasing the temperature from 50 to 70°C.
To investigate this phenomenon in detail, we havealso done two types of O K-edge XAS experiments;
one is the concentration dependence at 25°C and theother is the temperature dependence by using theconcentrated aqueous KNO2 solution (KNO2 : H2O =1 : 1.7, data not shown). In the former, the peak top
energy is also shifted to the lower energy withincreasing the concentration to pure solid. Sinceelectrolytes in aqueous solution generally decrease
the coordination of H2O and form aggregatedstructures with increasing the concentration, theobserved lower energy shift in Fig. 2b would

correspond to the similar phenomenon, i.e., thedecrease of the coordination number of water aroundNO2- in the higher temperature region (50 – 70°C). In
the latter, the tendency of the peak energy shift isalmost the same as the Fig. 2b. Thus, the observed
phenomenon in the temperature dependence of O Kedge XAS, which would arise from the decrease of
the H2O coordination, occur regardless of theformation of KNO2 aggregate structures.

Ⅲ-3

Fig. 1. (a) N K-edge (1s → π*) and (b) O K-edge
XAS (1s → π*) peaks of NO2- in aqueous KNO2
solution (KNO2 : H2O = 1 : 42.6) at various
temperatures (0 – 70°C).

Fig. 2. Temperature dependence of the peak top
energy shift in (a) N K-edge and (b) O K-edge XAS
from that at 25°C.
[1] Y. Marcus, Chem. Rev. 109 (2009) 1346.
[2] M. Nagasaka et al., J. Phys. Chem. B 121 (2017)10957.
[3] M. Nagasaka et al., J. Electron Spectrosc. Relat.
Phenom. 224 (2018) 93.

1095 Ⅲ03-

Ⅲ -3. Chemistry
BL4U
BL4U

Characterization of Meso Porous Monolithic Polymers Containing RAFT
Agent by Scanning Transmission X-Ray Microscopy (STXM)
D. Arrua1, A. Khodabandeh1, T. Ohigashi2, 3, N. Kosugi2, 3 and E. Hilder1

Future Industries Institute, University of South Australia, Building X, Mawson Lakes Campus, GPO Box 2471
Adelaide SA 5001, Australia
2
UVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585, Japan3
School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585,
Japan
1

Ⅲ-3

The preparation of hierarchically mesoporous
materials exhibiting two or more distinct pore size
distributions has found utility in diverse applications,
including catalysis and liquid separations [1]. The
defining parameters of the 3D network of such
system can be adjusted, however this is not a trivial
method. Typically, the polymerization is initiated via
thermal free radical polymerization which results inthe formation of linear polymer chains followed bycrosslinking and gelation steps. This mechanism iscalled polymerization-induced phase separation(PIPS) and the gelation step dictates the resultant
morphology and allows for control of the macro- andmeso-structure of a continuous piece of porous
material known as “monoliths”.
The gelation step can be tuned by using different
solvents in the monolith precursor, from well-known
organic solvents such as methanol, ethanol andacetone to some less famous large alcohol molecules
such as 1-dodecanol. For preparation of percolating
macropores,
polymericsolventssuchaspoly(ethylene glycol) with different molecularweights can be used as pore forming materials.
Introducing a RAFT agent (Reversible Addition−
Fragmentation chain-Transfer agent) to the above
system offered a control over the polymer mechanism
as well as on the morphology of the obtainedmonolithic polymers [2]. Respect to the surface
chemistry of the obtained well-defined 3D network,
an accurate characterization is required especiallywhen polymeric forming pore agents were utilized[3, 4].
The characterization by STXM of polymericmonolith materials was performed at the BL4U of the
UVSOR synchrotron facility. STXM imaging was
conducted by focusing on the C 1s core-line signal in
NEXAFS. Figure 1 shows the C 1s NEXAFS spectra
obtained for three monolithic polymers (A1 with no
RAFT agent, A2 and A3 with different amount of
RAFT agent). In all these monoliths, polyethylene
glycol (PEO Mw ~35K) were used as part of pore
forming material.
In our first assessment, the components found by
STXM were the poly (Sty-co-DVB) monolith domain,
and the embedding resin for three different monoliths(A1 to A3, with both 100 nm and 300 nm sections).
The spectrum for the crosslinked styrene-based
scaffold has a strong peak at 284.6 eV, which ischaracteristic of C 1s → π*C=C transition in a phenyl
ring. On the other hand, there is no strong peak forresidue PEO which is expected to retain in the sample.
Considering the size of the polymer globules (~50 nm,
estimated by scanning electron microscopy (SEM)) insample A2 and A3 as well as ~200 nm domain
between globules (formed via pore forming agent),
the export data via the region method could
potentially hide the signal of the PEO residue (poreforming material). This study is now in progress.

Fig. 1. NEXAFS reference spectra of the epoxy(embedding matrix), PEO Mw ~35K, RAFT agent
and polystyrene cross-linked monoliths (A1 with no
RAFT agent, A2 with RAFT agent (molar ratio
between [Initiator] 1: [RAFT] 1) and A3 with RAFT
agent (molar ratio between [Initiator] 1: [RAFT] 2)that correspond to 1 nm thickness of each component.
[1] D. Wu et al., Chem. Rev., 112 (2012) 3959.
[2] K. J. Barlow et al., Poly Chem, 5 (2014) 722.
[3] D. Arrua et al., UVSOR Activity Reports 42 (2014)76.
[4] A. Khodabandeh et al., Poly Chem, 9 (2018) 213.

1106 Ⅲ03-

Ⅲ -3. Chemistry
BL4B
BL4B

Metastable CS22+ States Studied by an Electron-Electron-Ion Coincidence
Method2

Y. Hikosaka1 and E. Shigemasa2

Institue of Liberal Arts and Sciences, University of Toyama, Toyama 939-0364 JapanUVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585 Japan1

Doubly-charged positive-ions of molecules areenergetically unstable due to the Coulomb repulsion
between the two positive charges, and they usually
undergo rapid dissociations into fragments. Mass
spectroscopy has however identified since long ago
the existence of metastable molecular dications
having lifetimes of the order of at least microseconds.
In this work, we have employed a magnetic-bottle
electron spectrometer adapted to ion detection, whose
description is elsewhere [1], and have performed anelectron-electron-ion coincidence study for the S2p
Auger decay of CS2, in order to identify theelectronic states of the metastable diaction.
The magnetic-bottle electron spectrometer isequipped with a strong permanent magnet and a longsolenoid coil, and an inhomogeneous magnetic fieldcreated in the ionization region forms a magnetic
mirror to collect the electrons from almost the whole
4π solid angle. An electrostatic retarder, which
consists of a 1.3-m long tube and three Mo meshes(94% transmission each), is installed inside thesolenoid tube [2]. For coincidence detection of thecounterpart ions, a pulsed high voltage was applied tothe ionization region, according to an electrondetection, and the formed ions were introduced into
the same microchannel plate detector for electron
detection.
A multi-electron ion coincidence measurement wasmade for CS2 at a photon energy of 321.4 eV(bandwidth of ~150 meV), by applying a retardationof 120 V for electron observations. The top panel ofFig. 1 shows a spectrum of dication states populated
after the Auger decay from the S2p core-hole states,
which is derived from the energy correlations
between photoelectrons and Auger electrons observedin coincidence. The energy resolution allows us tolocate different electronic states of CS22+, though thevibrational structures known for some specific CS22+
states are hardly identified. We can examine the ion
species produced from these dication states, byinspecting the coincidences among the two electrons
and ion(s). The two-dimensional map in Fig. 1 shows
the derived correlations, and ion spices formed fromthe individual dication states are presented. Dominantcoincidence with CS22+ is observed for the low-lying
diction states around 26-29 eV, and these states aremetastable having lifetimes longer than microsecond
order. In contrast, dication states lying above 30 eV
dissociate, before arriving the detector, mainly into
the fragments of S+ and CS+.

Ⅲ-3

Fig. 1. Two-dimensionalmapshowing
thecorrelations between the CS2 dication states and timeof-flights of ions, derived from the coincidencesamong two electrons and ion(s). Top panel shows aspectrum of dication states populated after the Auger
decay from the S2p core-hole states. The time-offlight spectrum of ions is displayed in the right panel.
[1] A. Matsuda et al., Rev. Sci. Instrum. 82 (2011)
103105.
[2] Y. Hikosaka et al., J. El. Spectrosc. Rel. Phemon.
192 (2014) 69.

1117 Ⅲ03-

Ⅲ -3. Chemistry
BL4B
BL4B

Multi-Electron-Ion Coincidence Spectroscopy: Auger Decay from Xe 4s
Core-Hole State
2

Ⅲ-3

Y. Hikosaka1 and E. Shigemasa2

Institue of Liberal Arts and Sciences, University of Toyama, Toyama 939-0364 JapanUVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585 Japan
1

Auger decay from core-hole states in atoms often
produces a variety of multiply-charged ions. Multielectron coincidence spectroscopy, which iseffectively achieved by using a magnetic bottle
electron spectrometer, is a useful tool to identify themultiple Auger decay pathways, overcoming theambiguities resulting from the overlap of Auger lines
from different core holes. The benefit of thisspectroscopy can be significantly increased when themulti-electrons are observed in further coincidencewith ions, because different multi-ionization steps
can be isolated by the observed ion charges.
In this work, we have performed multi-electron-ion
coincidence spectroscopy to study the Auger decay of
Xe 4s core-hole state. The multi-electron-ion
coincidence spectrometer utilized in this work isbased on a magnetic-bottle time-of-flight electron
spectrometer with ion detection capability [1],equipped with an electrostatic retarder to improve theenergy resolution in electron observations [2]. A
similar multi-electron-ion coincidence setup wasdeveloped by Eland et al. [3].
A multi-electron ion coincidence measurement wasmade for Xe at a photon energy of 350 eV(bandwidth of ~90 meV). The black curve in Fig. 1
shows an total Auger electron spectrum observed incoincidence with 4s photoelectron. The formation of
the 4d-15l-1 states is due to the Coster-Kronigtransitions from 4s-1, and that of 4d-2 to the superCoster-Kronig transitions. Structures below 40 eVarise largely from the overlap of the subsequent
decays of these 4d-15l-1 and 4d-2 states.
The Auger electron spectra coincident withindividual ions are compared in this figure. Clear
differences are observed among the spectral features.
This observation demonstrates that different Auger
pathways are clearly isolated by the coincidence
observation including ions. The spectrum coincident
with Xe3+ ion (shown in red) displays only the
structures assignable to the formation of the 4d-15l-1
states and their subsequent decays. Since the 4d-2
states proceed to sequential decays emitting
additional two Auger electrons [4], andcorresponding structures are isolated in the spectrum
coincident with Xe4+ ion (blue). The spectrum
coincident with Xe5+ ion (green), presenting the triple
Auger decay of the 4s core-hole state, shows a
distribution increasing gradually as decreasing the
kinetic energy, where no remarkable Auger structure
is seen.

Fig. 1. Auger electron spectrum (balck) observed incoincidence with 4s photoelectron, together with thespectra derived by further coincidence with ions of
Xe3+ (red), Xe4+ (blue) and Xe5+ (green).
[1] A. Matsuda et al., Rev. Sci. Instrum. 82 (2011)
103105.
[2] Y. Hikosaka et al., J. El. Spectrosc. Rel. Phemon.
192 (2014) 69.
[3] J.H.D. Eland et al., Chem. Phys. Lett. 548 (2012)90.
[4] Y. Hikosaka et al., Phys. Rev. Lett. 98 (2007)
183002.

1128 Ⅲ03-

Ⅲ -3. Chemistry
BL5B
BL5B

Zeeman Quantum Beat in Helium Fluorescence Decay Curve
T. Kaneyasu1, Y. Hikosaka2 and H. Iwayama3, 4

SAGA Light Source, Tosu 841-0005, Japan
Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
3
UVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
4
The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan1

2

When several quantum paths connect the initialand final states of atomic transition, the quantum
interference among these paths may cause quantum
beat in the physical observables of the system. The
quantum beat has been frequently observed influorescence decay following coherent excitation of
the atomic and molecular system using lasers [1]. In
that case, the laser pulse prepares the atomic system
in a coherent superposition of the several states. Thismethod can be applied to the atomic excitation usingsynchrotron radiation because it may cause coherent
excitation of several levels within a bandwidth of themonochromatized light. We planned to use thequantum beat phenomena to study the magnetic
sublevel population in the vortex-atom interaction [2].
As a first step of the quantum beat study, weobserved the Zeeman quantum beat in helium
fluorescence decay curve.
The experimental scheme is shown in Fig. 1. The
experiments were performed at BL5B. The
fluorescence decay curve was measured using the
VUV pulse provided by the single bunch operation of
the UVSOR ring. We observed the UV or visible
fluorescence following the 1s→np (n=4-7) excitationof helium atoms at the VUV wavelength region. A
weak magnetic field of several tens of Gauss wasapplied to the interaction region. The direction of themagnetic field was parallel to the photon propagation
axis. This magnetic field induced the Zeeman shift ofthe magnetic sublevels Mj=±1 which caused theinterference in the decay paths. Thus it was expectedthat the fluorescence decay curves show beatstructure which oscillates at frequency 2ω according
to the Zeeman shift energy of ħω.
Figure 2 shows the measured decay curves
following the 1s→6p excitation. In accordance with
the interference model described above, we foundthat the beat structure was superimposed on the decay
curve and its oscillating frequency increased when
the solenoid coil current increased. The observed beatfrequency agrees well with the Zeeman shiftestimated by the magnetic field measurement.
Furthermore the beat structure vanished when themagnetic field was parallel to the electric field vectorof the VUV pulse (not shown here). This is because
the dipole-allowed magnetic sublevel is limited to
Mj=0 in this configuration. These results strongly
support the reliability of the quantum beatmeasurement using the synchrotron radiation.

Fig. 1. (a) Experimental setup for observing thehelium Zeeman quantum beat. The magnetic field
was produced by solenoid coils. Helium atoms were
excited by the VUV pulses of 178 ns repetition. The
UV or visible fluorescence was detected by aphotomultiplier tube. (b) Energy level diagram of thehelium atom and excitation/decay pathways in thepresent study.

Fig. 2. Fluorescence decay curves of the 1s6p
excited state of helium. The wavelength of theexcitation pulse was set to 51.2 nm while thewavelength of the fluorescence was 345 nm.
[1] H. Bitto and J.R. Huber, Opt. Comm. 80 (1990)
185.
[2] A. Afanasev et al., Phys. Rev. A 88 (2013)
033841.

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BL6U
BL6U

Mass Spectra of Xenon Difluoride in Coincidence with the F KVVand Xe M45N45N45 Auger Electrons
M. Kono1, 2, 3, F. Yamashita4, H. Iwayama5, 6, K. Okada4 and E. Shigemasa5, 6

School of Science and Technology, Kwansei Gakuin University, Sanda 669-1337, Japan
2
Senri International School of Kwansei Gakuin, Minoh 562-0032, Japan
3
RSPE, Australian National University, Canberra, ACT 2601, Australia
4
Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
5
UVSOR Synchrotron 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

Ⅲ-3

Xenon difluoride attracts the attention of X-ray
spectroscopists because it has similar binding
energies among Xe 3d5/2, Xe 3d3/2 and F 1s subshells[1]. Southworth et al. [2] have recently measured thepartial ion yield curves of XeF2 and found that the
charge state distribution of Xeq+ shifts down
compared to the Xe atom case. Our previous study[3] has been concerned with the Auger spectra to get
an insight into the molecular electronic states leading
to the production of Xeq+. The results show that at theσ* resonance the F KVoVo peak is most intense,
while the Xe M5N45N45 transitions are dominant at
the shape resonance. Here the symbol Vo meansouter- valence orbitals. By comparison of our resultswith the study by Southworth et al., there exists a
strong correlation between the Auger transitions andfragmentation channels. In order to justify thisdirectly, here we conducted the Auger-electron–
photoion coincidence (AEPICO) measurements.
The present experiments were performed on thesoft X-ray beamline, BL6U, and its setup has been
described elsewhere [4]. In brief, a monochromatizedlight beam of synchrotron radiation was irradiated atright angles to the effusive beam of the sublimated
XeF2 sample. The pressure of the main chamber was
kept at 1.0 × 10−3 Pa during all the measurements.
Auger electrons traveling through a double toroidal
analyzer tube were detected with a position sensitive
detector. Pass energies of the analyzer were set to 400
eV. Each electron detection triggered a pulse ofelectric field applied across the interaction region,
extracting photoions toward a time-of-flight mass
spectrometer. The coincidence data were obtained as
list-mode files, containing a series of the detected
electron positions and the ion-arrival time andpositions. The photon energy was set at 707.3 eV inthis study.
Mass spectra of the photoions coincident withparticular Auger electrons can be obtained byextracting the electron kinetic-energy region ofinterest from the acquired data. The most abundantphotoion is F+ for both the F KVoVo and Xe
M4N45N45 regions, while the charge distribution of
Xeq+ differs from each other. The Xe M4N45N45AEPICO spectrum is shown in Fig. 1. The maximum

yield of Xeq+ comes at the trivalent ion, which is incontrast with the atomic Xe case where the exclusive
production of Xe4+ is observed [5]. Based on the
proposed transition channel for the Xe4+ production
following the M45N45N45 Auger process of Xe [5], thelower-charged Xe ions are presumably formed
through similar transition channels leading to theelectron configurations with the holes in the 5πu and10σg orbitals. Since the latter orbital has an F 2p
character, the charge(s) can be put on fluorine as well,accounting for the formation of the F+ and F2+ ions.

Fig. 1. The photoion mass spectrum of xenon
difluoride in coincidence with the Xe M4N45N45
Auger electrons. The spectral data were acquired at
the photon energy of 707.3 eV.
[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] F. Yamashita, M. Kono, H. Iwayama, K. Okada
and E. Shigemasa, UVSOR Activity Report 44(2017) 111.
[4] R. Tateishi, T. Kaneda, H. Iwayama, M. Kono, K.
Okada and E. Shigemasa, UVSOR Activity Report 43(2016) 104.
[5] Y. Tamenori, K. Okada, S. Nagaoka, T. Ibuki, S.
Tanimoto, Y. Shimizu, A. Fujii, Y. Haga, H. Yoshida,
H. Ohashi and I. H. Suzuki, J. Phys. B: At. Mol. Opt.
Phys. 35 (2002) 2799.

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BL6U

Site-specific Production of H3+ by Core Ionization of CH3Cl
H. Fujise1, 2, H. Iwayama1, 2 and E. Shigemasa1, 2

UVSOR Synchrotron 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

The trihydrogen cation, H3+, is an interesting
molecule which plays a key role in reactions that leadto complex molecules characterizing interstellar
clouds [1]. H3+ can be produced from fragmentation
reactions of several hydrocarbon molecules using
intense laser fields [1], soft X-rays [2], and electron
impact [3]. Previous results, irradiating soft X-rays tochloromethane, CH3Cl, suggested that H3+ waspreferentially produced and related to the site-specificAuger final states obtained after the core ionization of
the Cl 2p electron [4]. However, the detailed
production mechanism is still unknown. In this study,
we investigate the site-specific production
mechanism of H3+, and its responsible ionic state ofCH3Cl2+, by core ionization with soft X-rays andAuger-electron-ion coincidence measurements, aswell as comparing the results with deuterated
chloromethane, CD3Cl.
Experiments were performed on the soft X-ray
BL6U. Radiation from the undulator was
monochromatized and focused onto the interaction
region of an Auger-electron-ion coincidence
spectrometer. The target gas was introduced into theinteraction region by effusion from a capillary tube:
produced Auger-electrons were energy-analyzed by
the double toroidal analyzer (DTA). Ions in theinteraction region were extracted towards the ion
momentum spectrometer by an applied pulsed
electric field, according to each electron detection.
The electron pass energy of the DTA was set to 200
eV, and the corresponding energy resolution was ~1.9
eV. The photon energy used for Cl 2p core ionization
was 220 eV.
Figure 1(a) shows the total Auger spectrum andcoincidence Auger spectrum after the Cl 2p coreionization of CH3Cl. The coincidence spectrum is
extracted from the total Auger spectrum, using thetime-of-flight information of H3+. The vertical lines
above the experimental data are the theoreticallycalculated Auger final states, along with their valence
electron configuration, which are listed on the right.
The coincidence Auger spectrum has a single peak at~31 eV, which is hardly observed in the case of the C
1s core ionization [4]. This indicates that the H3+
formation process occurs site-specifically through the
Cl 2p core ionization, with a relation with the 3e-2
Auger final states. To give further insight into themolecular dynamics of the dissociation mechanism of
H3+, a comparison experiment was conducted, using
deuterated chloromethane, CD3Cl. Figure 1(b) shows

the total Auger and coincidence Auger spectra after
the Cl 2p core ionization of CD3Cl. The coincidence
Auger spectrum in Fig. 1(b) has a similar spectral
profile compared to the CH3Cl case in Fig. 1(a),where the only difference seen is the lower
coincidence detection rate of the D3+ fragment ions.
The similar spectral profile strongly suggests thesame 3e-2 Auger final states involved in the
dissociation mechanism. Furthermore, because thedeuterium atom is twice as heavy than the hydrogenatom, molecular motion around the deuterium atom isrepressed. The lower abundance of D3+ implies thatmolecular deformation due to vibrational motion
around the C-D bond is suppressed, which resulted indecreasing the abundance of D3+.

Fig. 1. Total Auger spectra (black) and coincidence
Auger spectra (red) following Cl 2p core ionizationfrom (a) CH3Cl and (b) CD3Cl.
[1] J. H. D. Eland, Rapid Commun. Mass Spectrom.
10 (1996) 1560
[2] S. Pilling et al., Mon. Not. R. Astron. Soc. 375(2007) 1488.
[3] K. Hoshina et al., J. Chem. Phys. 129 (2008)
104302.
[4]H. Iwayama and E. Shigemasa, UVSOR Activity
Report 2015 43 (2016) 107.

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BL6U
BL6U

Intermolecular Coulombic Decay of Core Excited Nitrogen Molecular
Clusters
H. Iwayama1, 2

UVSOR Synchrotron 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

Intermolecular Coulombic decay is an efficientelectronic relaxation of excited molecules placed in aloosely bound chemical system (such as a hydrogenbounded or van-der-Waals-bounded cluster). This
decay process ionize neighboring molecules to
excited one and eject low-enegy electrons, whichplay an important role in DNA damage induced
ionizing radiation. Recently, it was proposaled thatemission site and energy of the electron released
during this process can be controlled by coupling the
ICD to a resonanct core excitation [1]. These
properties may have consequences for fundmental
and applied radiation biology. In this work, weinvestigated ICD process of core excited nitrogenmolecule clusters by using Auger-electron ion
coincidence technique. Since ICD process lower the
double ionization threshold, we measured binding
energy of Auger states corresponding to double
ionizations. Compared to isolated nitrogen molecules,
we observed lowering of double ionization thresholdfor nitrogen molecular clusters.
The Auger-electron-ion coincidence measurements
were performed on the undulator 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 220K. The
stagnation pressure is 8 bar. The average cluster size
was estimated to be ~10 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 molecularions of N2+ and fragment ions of N+. For clusterednitrogen, we observed cluster fragment ions of (N2)n+(n≧2) and (N2)nN+ (n≧1) in addition to N2+ and N+
ions.
To investigate double ionization thresholds, we
explore the events where we detected two fragment
ions in coincidence with an Auger electron. Figure 2
shows Auger spectra in coincidence with two
fragment ions for (a)isolated and (b)clusterednitrogen. The binding energy distribution of Auger
states resulting in double ionizations for nitrogenmolecular clusters are significantly lower thanisolated nitrogen molecules. The enhancement aroundbinding energy of 45 eV corresponds to the ICD
process of core excited nitrogen molecular clusters.
Analysis in more detail is in progress.

Fig. 1. Time-of-flight mass spectra for (a) N2
molecules and (b) clusters.

Fig. 2. Coincidence Auger spectra with two
fragment ions for nitrogen molecules and clusters.
[1] K. Gokhberg, et al., Nature 505 (2014) 661.
[2] R. Flesch, et al., Phys. Rev. Lett. 86 (2001) 3767.

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BL6B
BL6B

Microfluidics of Liquid Mixtures for Infrared Microscopy
M. Nagasaka1, 2, A. A. Vu1, 3, H. Yuzawa1, N. Takada1, M. Aoyama1, E. Rühl3 and N. Kosugi1, 2Institute for Molecular Science, Okazaki 444-8585, JapanSOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan3
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 the liquid phase[1]. Recently, X-ray diffraction in the hard X-ray
regime has been used for a variety of systems byusing microfluidics [2]. Previously, we applied
infrared (IR) microscopy to characterize microfluidic
flows [3], but the microfluidic channel was notcompletely sealed at that time. Recently, we have
improved the microfluidic cell for soft X-ray
absorption spectroscopy and successfully observed alaminar flow in the mixed part of the microfluidic
system [4]. In this study, we have used it for IR
microscopy.
The experiments were performed by using the IR
microscopy setup IRT-7000 at BL6B. A T-shape
microfluidics setup with the width of 50 μm is madefrom PDMS resin which is covered by a 100 nm
Si3N4 membrane. The spatial resolution of 30 × 30
μm2 is reached by using a ×16 Cassegrain mirror. IR
spectra are taken by detecting the reflected infrared
light by an MCT detector.
Figure 1 shows IR spectra of pyridine and watertaken from the mixed part of the microfluidic cell, at
positions shown in Fig. 2. The IR spectra correspondto the OH stretching vibration of water around 3392
cm−1 and the CH stretching vibration of the pyridine
ring around 2936 cm−1, respectively. The absorbanceof water and pyridine at different positions is
obtained from the fitting results of the IR spectra toboth the vibrational peaks.
Figure 2(a) shows the 2D image of the absorbanceof water. Pyridine (P) flows from the upper side, andwater (W) from the lower side. The water-pyridine
mixture (M) flows to the right-hand part after thejunction of the liquids. In the mixed part of the
microfluidic flow, the absorbance of water showshigh intensity at Y = 120 μm. On the other hand,
Figure 2(b) shows the 2D image of the absorbance ofpyridine, which shows high intensities at Y = 150 μm.
These results suggest that the mixed part of the
microfluidic flow is evidently laminar between Y =120 and 150 μm. IR microscopy enables us toobserve both chemical compounds separately by
selecting their respective vibrational modes.
[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., UVSOR Activity Report 2016(2017) 116.
[4] M. Nagasaka et al., in this volume.

Fig. 1. IR spectroscopy of pyridine (P) and water(W) in the mixed part of the T-shape microfluidic cell,at positions shown in Fig. 2.

Fig. 2. The 2D images of the absorbance of (a) waterand (b) pyridine in the T-shape microfluidic cellobtained from IR spectra at different positions.

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