BL3U

Construction of the 2m-Long in-Vacuum Undulator Beamline BL3U

T. Hatsui, H. Setoyama, S. Masuda, N. Kondo*, E. Nakamura*, Shigemasa*, N. Kosugi
Dept. of Vacuum UV photoscisence, Institute for Molecular Science, Okazaki 444-8585 Japan*UVSOR facility, Institute for Molecular Science, Okazaki 444-8585 JapanThe undulator beamline BL3U has been designed
and constructed for photoelectron spectroscopy (PES),
soft x-ray absorption spectroscopy (XAS), and soft
x-ray emission spectroscopy (XES) for the energy
range from 60 to 800 eV. A soft x-ray emission
spectrometer generally requires small beam size at thesample position, because a smaller opening of thespectrometer entrance slit is needed to achieve higher
energy resolution. Such a beam is usually produced
by refocusing optics downstream of the exit slit. In
our case, the adoption of such refocusing optics isimpossible, due to the very limited space. On theother hand, a monochromator with short arm lengths
is utilized with a small exit-slit opening for obtaining
practical resolution. It is feasible to carry out XES
studies at the exit-slit position, if the monochromator
has a constant exit-arm length. We have designed avaried-line-spacing
plane(VLSP)
grating
monochromator in order to satisfy high energy
resolution and small width of the exit-slit opening.
Figure 1 represents the layout of the beamline BL3U
at the UVSOR facility. The in-vacuum plane
undulator composed of 50 periods of 3.8 cm period
length is installed in a straight section, where theelectron beam parameters are sx=602 mm, Vx'=49.9mrad, Vy=61.3 Pm, and Vy'=40.6 mrad. The brillianceand total flux calculated by using SPECTRA ver.
7.0.5 [1] are shown in Figure 2. The cylindricalmirror M0 vertically focuses the beam on theentrance slit S0 with the demagnification of 1/7.57.
The typical beam size at the entrance slit S0 is a full
width at half maximum (FWHM) of 22 Pm. Due tothe short arm length, the entrance-slit opening
corresponding to the resolving power of E/'E=104
becomes smaller than the beam size. This mismatch
causes the beam loss of 12-63%. Varied-line-spacing
parameters are calculated by minimizing theaberrations in the energy range of interest. The
analytical solution of the aberrations for an
S0-M1-VLSP-S1 optical system derived by Amemiya
et. al. [2] is used. The obtained parameters give
resolving power higher than E/'E=104 in the photon
energy range of 50-800 eV by using threeinterchangeable gratings with the center groove
densities of 1200, 600, and 240 l/mm. G
In the XES setup of Figure 1, the beam ishorizontally focused on the exit slit by aplane-elliptical mirror M2X, which is locateddownstream of the VLSP gratings. A sample is placed
at 5-10 mm downstream of the exit slit S1X. In themulti-purpose setup, the beam is focused on the exitslit S1 only vertically and then refocused in the bothdirections on the sample by a toroidal mirror M2. TheM2X mirror and the exit slit S1X are designed to beeasily interchangeable with the exit slit S1. In theXES setup, the beam on the sample is designed tohave a gaussian distribution with FWHM of 60 Pm
horizontally. The vertical beam size is close to theopening of the exit slit S1X. Although the beam isdiffracted by the exit slit S1X, the vertical size of thebeam can be down to ~10 Pm; in the multi-purpose
setup, the beam size at the sample position istypically 30(v) x 170 (h) Pm2.
The commissioning has started from March 2004.
The fitting of the N 1s ĺS* resonance spectrum(Fig.3) gives the monochromator resolution of 7200,
where the Lorentzian width of 109 meV was assumed[3]. The resolution is lower than the designed value.
The reason was found to be the misalignment of thegratings. Improvement of the alignment is now underprogress.
Top View

XES Setup

S0

S1X

M1: Spherical G: VLSP
R=88.826 m

in-vacuum
M0: Cylindricalplane undulator R=47.253 m

sample176°

M2X: Plane-Elliptical
r1=11.7 m
r2=0.5 m
M2: Toroidal
R=81.65 m
ρ= 37.23 mm

Multi-purpose setup S1

sample176°

70005300

3100
6000

4009100

Side View

2203

5009500

11703

G

M2X

800
12203

13003

14603

S1X
sample

176°
177°

1600

173°

M1

S1

M0

M2

sampleFig. 1. Schematic layout of the BL3U.

Total Ion Yield (couFig. 2. Theoretical estimates of the undulator
brilliance and flux, and the photon flux at sample
position.
43x10
Gaussian width = 55.5 m(not optimized yet)210400.0

400.5

401.0

401.5

Wavelength,402.0402.

Fig. 3. Total ion yield spectrum of nitrogen moleculeusing the grating with groove density of 1200 l/mm.
[1] T. Tanaka, and H. Kitamura, J. Synchrotron Rad. 8,(2001) 1221.
[2] K. Amemiya, et. al., J. Synchrotron Rad. 3, (1996)
282.
[3] H. Ohashi et. al., Nucl. Instr. And Meth. A
467–468 (2001) 533.

37

BL3U

Design of a Transmission Grating Spectrometer for X-ray Emission Studies
T. Hatsui, E. Shigemasa*, N. Kosugi
Dept.of Vacuum UV photoscience, Institute for Molecular Science, Okazaki 444-8585 Japan*UVSOR facility, Institute for Molecular Science, Okazaki 444-8585 Japan
High resolution soft x-ray emission spectroscopy(XES) in combination with synchrotron radiation asincident soft x-rays has been extensively studied since
the development of a high energy resolution
spectrometer by J. Nordgren et. al [1]. The design of
their grazing-incidence spectrometer is based on theRowland circle mount. In this case, the horizontal
acceptance angle is mainly limited by the detector
size. In order to achieve higher resolution, theRowland radius, R, or the spectrometer size, should
be larger due to the relationship of O'Ov R. The
detector size is however limited. It is therefore
desirable to design a novel optical system which canfocus the emitted x-rays not only in the (vertical)
dispersion direction but also in the other (horizontal)
direction. In addition, recent advances make thecharge-coupled devices (CCD) a promising soft-x-ray
detector. It is however not a trivial problem to adopt itin the high resolution Rowland spectrometer, since
the CCD detectors have low quantum efficiency at
the small grazing-incidence angle. In this report, we
propose a novel spectrometer design for highresolution soft x-ray emission studies.
Figure 1 shows the schematic layout of atransmission-grating spectrometer (TGS). In order tofocus the emitted x-ray both horizontally andvertically, a Wolter type I mirror is introduced as theprefocussing mirror with a magnification of 10. The
Wolter mirror consists of hyperboloidal and ellipticalsurfaces. The grazing-incidence angle of 1 degree
gives a collection angle of 1.5 x 10-3 sr. A
free-standing transmission plane grating with its
groove density of 10 000 lines/mm is placed at 67
mm downstream at the edge of the Wolter mirror, inthe normal incidence geometry. A back-illuminated
CCD, of which the position is changed along theRowland torus with scanning the photon energy, islocated at 1400 mm downstream from the grating.
For evaluating the aberrations of TGS, aray-tracing code TGSGUI is originally developed byone of the authors (T.H.). In the case of a rectangularsource, the Wolter mirror has considerable amount ofthe aberration. Figure 4 presents a spot diagram at thedetector position for the 0th order diffraction with arectangular source of 1(v) x 200(h) Pm2. This result
suggests that the aberration is negligible for thissource size. Figure 4 (right) indicates a spot diagramof the 1st order diffracted rays of 320 eV at thedetector with a rectangular source of 1x200 Pm2.
Other aberrations arise from the plane figure of thegrating [2]. The diagram however indicates that thepresent TGS has small amount of the aberrations. The
resolving power better than 5000 is possible. The
spatial resolution of the detector should be very high,which is estimated to be about 1 Pm, in order toachieve such a high resolution.

Fig. 1. Spot diagram of the 0th (top) and 1st (bottom)
order diffraction at the detector with a rectangularsource of 1(v)x200(h) Pm2 (top).
[1] Nordgren, et.al., Rev. Sci. Instrum. 60, 1690-1696(1989).
[2] Beuermann, K.P. et.al., Applied Optics
17,2304-2309 (1978).

Fig. 1. Schematic layout of the transmission-grating
spectrometer (TGS) (up). A cross sectional view isalso shown (bottom).

38

BL4B

X-ray Magnetic Circular Dichroism Measurements at BL4B
T. Nakagawa, H. Watanabe, K. Maruyama, T. Yokoyama
Department of Molecular Structure, Institute for Molecular Science, Okazaki 444-8585 Japan
X-ray magnetic circular dichroism (XMCD) is a
powerful technique to investigate element-specificmagnetization. Moreover, by using so-called sum
rules, orbital and spin magnetic moments areseparately obtainable, which are hardly derived byother conventional magnetic measurements. We haveconstructed a new ultrahigh vacuum (UHV) chamberfor XMCD and surface XAFS (X-ray absorption finestructure) measurements at BL4B in upgraded
UVSOR-II. Here, basic performance of our XMCD
measurement system is described.

current from the sample, and a microchannel plate(MCP) is also available for the partial electron yielddetection with a retarding field under the remanentcondition. XMCD spectra are taken by changing thehelicity of the X rays or the direction of the magneticfield. Most equipments such as the upstream slit, themonchromator, the magnet and the detection systems
are controlled by the LabView software.

Results
In order to show the performance of BL4B and theXMCD system, we have recorded Co LIII,II-edge
XMCD of 3 monolayer (ML) Co on Cu(001). The
substrate Cu(001) was cleaned by repeated cycles ofAr+ sputtering and annealing to ~900 K (electronbombardment from the rear side). Cleanliness andorder of Cu(001) were verified by XAFS and LEED,respectively. Co was deposited from the Omicron
EFM3 evaporator. Co is known to grow epitaxially onCu(001) with a layer-by-layer pseudomorphic fashionand to show the in-plane easy axis.
Figure 2 show the XMCD spectra, taken at the
x-ray incidence angles of 30q (grazing incidence,close to the easy axis) and 90q (normal incidence,along the hard axis). It took around 12 min. to recorda parallel or antiparallel spectrum. A signal-to-noise
ratio is fairly well. The normal incidence spectra
show much weaker XMCD signals because themagnetization is not saturated at 2000 G.
We have performed the sum rule analysis. Theorbital moment ml of 0.164 (PB) and the effective spin
moment ms of 1.65 (PB) for the T=30q spectra, while
ml/ms= 0.095 for the T=90q ones. These values are
consistent with previously reported values.

Apparatus
BL4B is a bending magnet station, where avaried-line-spaced grating monochromator is installed.
Circularly polarized X rays are obtained by placing a
newly installed slit (located in the upstream of thefirst mirror) upward or downward with respect to theelectron orbit plane. A polarization factor Pc of ~0.70
was obtained with a reasonable photon intensity andan energy resolution E/'E of ~700 at the energy
range of 600-1000 eV.
Figure 1 shows the inside of the UHV chamber. AnAu-coated Fe electromagnet allows us to apply astatic magnetic field of maximum 3000 G during
XMCD measurements. The X ray is introduced
through the holes at the center of the magnet poles,
and its propagating direction is thus always parallel or
antiparallel to the magnetic field.
The UHV chamber is evacuated by turbo molecular
pumps, a non- evaporation getter and a Ti sublimation
pump. The base pressure is around 1u10-10 Torr.
Standard surface cleaning equipments such as an ion
gun, a heater and a LEED/RHEED optics are installed.
Metals and gases can be deposited by commercial
evaporators and leak valves, respectively. A sample
can be cooled down to ~100 K using liq. N2. The
sample can be rotated in both the polar and azimuthal
directions with respect to surface normal.
The signals were detected usually by a drain

Fig. 2 Co LIII,II-edge XMCD of 3 ML Co/Cu(001)at the x-ray incidence angles of 30q and 90q.

Fig. 1 Inside look of the UHV chamber.

39BL5U

Present Status of High-resolution Angle-resolved Photoemission
Spectroscopy Apparatus at BL5U

T. Ito, S. Kimura, K. Takahashi1, K. Soda2, T. Takeuchi3, K. Shinba2, T. Kondo3,
T. Nakagawa4 and N. Kosugi
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 Japan
1
Synchrotron Light Application Center, Saga University, Saga 840-8502, Japan2
Department of Crystalline materials Science, Nagoya University, Nagoya 464-8603, Japan
3
Research Center for Advance Waste and Emission Management, Nagoya University, Nagoya464-8603, Japan
4
Department of Molecular Structure, Institute for Molecular Science, Okazaki 444-8585, Japan
Functionalities (superconductivity, magnetism, etc.)
originating from the electronic structure near theFermi level (EF), especially the Fermi surface of solids,
thin films and surfaces. To pursue the experimental
investigation of the functionalities of materials, wehave constructed a new high-energy-resolution
photoemission apparatus for the helical undulator
beam line BL5U.
Figure 1 shows a present status of the apparatus
installed at BL5U [1]. The most striking point is a
new type hemispherical photoelectron analyzer,MBS-Toyama ‘Peter A-1’, with which we haveachieved the world record of the experimental
energy-resolution 'E~1.2 meV, which has been
evaluated from the fitting of the PES spectrum near EFofAuby
temperature-dependent
Fermi-distribution-function broadened by Gaussian(Fig. 2).
To evaluate the improvement of the photoemission
spectrometer for BL5U, the XPS spectrum of Si(111)
7x7 surface obtained by the present apparatus iscompared with that by the previous one (Fig. 3). In
Figure 3, the present spectrum seems to have someadvantages to the previous one, i.e., the better S/N, thesharper double peak structures originating from Si 2p
spin orbit splitting, in spite of the compatible
experimental conditions (photon energy, temperature,sizes of slits, surface preparation). The observed
differences strongly suggest the improved efficiency
as well as the energy resolution of the present
spectrometer, though the upgrade of UVSOR isresponsible for the better S/N.
Finally, we will briefly comment on the future issues
for the experimental study of the functional materials
at BL5U. After the upgrading UVSOR and thereplacement of the photoemission apparatus, someweak points were revealed. Then, we plan theupgrade of BL5U in April 2004; (1) change of thespherical-mirror adjuster with high efficient watercooling, (2) installation of new spherical grating fornormal incident region (hQ=5~30 eV), and (3)installation the cooling system at the entrance slit.

Fig. 1High-resolution photoemission spectroscopy
apparatus at BL5U.

Fig. 2 PES spectrum around EF of Au film obtained byusing He ID photons at 5 K (red circles). The
results of fitting is superimposed (blue line).

[1] S. Kimura et al., UVSOR Activity Report 2002,
75.

Fig. 340Si 2p photoemission peaks obtained with theprevious (blue) and present (red) apparatus
installed at BL5U.

BL6B

Construction of the new IR and THz beam line BL6B

S. Kimura1,2, E. Nakamura1, T. Nishi2, K. Hayashi1
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 Japan2
Department of Structural Molecular Science, Graduate University of Advanced Studies,Okazaki 444-8585, Japan1

At the beginning of FY2004, the new infrared(IR) and terahertz (THz) beam line BL6B isconstructed. The design concept and the expected
performance have been already reported. [1,2] In
this paper, the configuration of the Fourierinterferometers and the end stations and the future
plan are reported.
The configuration of the beam line is shown in
Figure 1.
IR-synchrotron radiation (IRSR) iscollected by a perfect focusing mirror, so-called“magic mirror” set in the bending duct B6. IRSR isguided by two plane mirror and is focused at the first
focusing point. The polarization is changed fromhorizontal at the emission point to vertical by the twoplane mirrors. The first focusing point was shifted
about 300 mm to the outside of the storage ring
because of the installation of a newly installedradiation shield.
The ultra-high vacuum in the storage ring and in
the front-end part is separated at the window
exchanger with a diamond and a z-cut-quartz
windows before the first focusing point. IRSR isguided to two interferometers, one is old Michelson
FT-IR (Bruker IFS66v) and the other newly installed
Martin-Puplett FT-FIR (JASCO FARIS-1). Since
the new FT-FIR is rapid-scan type, higher accuracy ofintensity is expected. The covering wave number
range is from less than 10 cm-1 up to 20,000 cm-1.
The IRSR after two interferometers is guided tothe free port. Before the upgrading, a conventional
sample chamber was located at the position. To
support higher level experiments, users can set theirown chambers to the port. The old conventional
sample chamber and the old infrared magneto-optical
apparatus can be also located, of course.
In the near future, a commercial IR microscope
will be installed. The microscope will cover not
only IR region but also THz region because thebrilliance in the THz region is much higher thanconventional light sources. The THz microscope
will be a good probe for vibrations of large moleculein a small region and a metal-insulator imaging.
[1] S. Kimura et al., UVSOR Activity Report 2002, p.
78 (2003).
[2] S. Kimura et al., Proc. SRI2003.

Magic mirror
B6
BL6U
First focusing
point
Martin-Puplett
FT-FIR

Radiation
shieldMichelson
FT-IRFreeport

IR microscope(planned)

Fig. 1. Schematic figure of top view of the new infrared and terahertz beam line BL6B.

41

BL8A

Carbon Contamination of SR Mirror

M. Tadano1, E. Nakamura2, M. Hasumoto2,
T. Naito1, J. Urakawa1
1
High Energy Accelerator Research Organization, 1-1OhoTsukuba 05-080, Japan
2
Institute for Molecular Science, Okazaki 444-8585, Japan
Carbon contamination on SR irradiated mirror
was investigated as a series of the BL8A experiment
Vacuum pump oil was checked as one factor as
contamination to the mirror surface in the experimentof the preceding year.[1] We experimented by puttingin oil in a vacuum in order to advance contaminationon the surface of a mirror. Moreover, since it wasassumed that oil dissociated to a carbon simple
substance by irradiation, it tried how to apply anelectric field to the processed thing. The effect of theelectric field was investigated in this experiment byusing the carburizing technique.
Although much time was spent on experimentpreparation, the very interesting result was given. In
the environment where electric fields differ, the result
from which the amount of generation of a carbon
contamination differs was obtained.(fig.1)
The
progress of the carbon contamination was measured
under oil molecule existence that was apply the SR for
4 hours. Fig.2 shows the reflectivity reduction of thesurface of the mirror in each condition. The reflectivity
reductions were 73% for +1.5kV, 65% for withouthigh voltage and 50% for -1.5kV, respectively. Fig.3
shows the profile of the SR irradiation mirror as acontour color plot. The clear electric field dependence
was confirmed. From this result, we can conclude thatthe electric field at mirror surface is effective forreduce the carbon contamination. However, since
there is few measurement data, the quantities talk isnot made.
In this experiment, it is not experimenting inchanging voltage etc. Change of the reflectanceaccompanying voltage change is an interesting point.
It expects that the same data is obtained also in purevacuum environment. More exact investigation isneeded about dependence of the strength of an electricfield, and dependence of vacuum conditions. Although
this time was only found out delaying condition, things
were not made to removing contamination. We need
the further experiment for find out the other method of
the carbon contamination.

Fig.1. Picture of the contaminated copper mirror.

Fig.2. Reflectivity of irradiated mirror.
upper line: Plus High Voltage,
middle line: No High Voltage,
lower line: Minus High Voltage.

Fig.3. Mirror surface scan at after experiment.
upper round area: No High Voltage,
middle round area: Minus High Voltage,
lower round area: Plus High Voltage.
(unit at the time of measured [Volt].)[1] M.Tadano et.al. UVSOR Activity Report2002 P80[2] T.Naito et.al UVSOR Activity Report2000,P6342