6Surfacescience,
photochemistry
andOthers
123

BL4A

Development of Differential Pump System for Studies the Effects of XeF2
Etching of Si and SiO2 Induced by Synchrotron Radiation

1

T. Y. Chiang1, T. Makimura2, K. Murakami2, N. Nakai3, H. Uno1, R. Tero1,3, T. Urisu1,3
Dept. of Vacuum UV photo-science, Institute for Molecular Science, Okazaki 444-8585 Japan
2
Institute of Applied Physics, Tsukuba Univ., Tsukuba 305-8577 Japan
3
Graduate University for Advanced Studies, Okazaki 444-8585 JapanAn etching system was constructed to clarify thedifference between synchrotron radiation (SR)-induced reaction and dark reaction in XeF2 etchingof Si experiment at the beam-line BL4A1 in theUVSOR last year, and an etching rate of 0.9 μm/min
on Si surface was achieved. A XeF2-flow chamber
isolated and evacuated independently with a LiF
window is installed in the end-station beam chamber,in order to avoid the damage of vacuum pressure andevacuation instruments in the beam-line. However,the LiF window is damaged easily owing to theviolent collision of photon. So an apparent result can
not be observed at long-time performances thatescape the balance of selective and non-selective
reactions of XeF2 Etching on Si.
In order to eliminate the constraint imposed by thedamage on the entrance window of the reaction cell, a
differential pump apparatus system has beendeveloped. The entrance window is replaced by anaperture and a sequence of pressure stages which
reduce a pressure of 0.5 Torr in the reaction cell to
10-9 Torr in the pre-mirror chamber as shown in Fig.1and Fig. 2. By means of this technology a higher
energy resolution and a beam size of 1 mm in theenergy direction can be obtained.
The non-condensed beam spot of incident beam
after pre-mirror chamber is about 1010 mm2. Inorder to focus the beam trajectory to pass through theaperture, a paraboloid mirror is designed to condense
the divergent incident beam. As illustrated in Fig. 3,
the horizontal beam profile far from pre-mirror is
expected to be condensed at sample position.
A part of the beam condensed apparatus wasfabricated and an extremely high etching rate andspacial resolution was obtained from a performance
test of Teflon etching. After the setting up of new
etching chamber, we are planning to study the SR
irradiation effects on the material selectivity ofetching between Si and SiO2, to find whether there
exist an anisotropic character in desorption reactionof XeF2 etching induced by synchrotron radiation.
Etcher Gas Injected
10—— Reaction Cell—— Mirror ChamberPressure [Torr]

1x10 -1—— 3rd Chamber

1x10 -3

1x10 -5

1x10 -7051015202530Time [sec]Fig. 2 Characteristic of the pressure variation indifferential pump system after etcher gas injected bysimulation - The system restrains the variation ofpressure from etcher injection, and obtains
achievement of experiment pressure.

Fig. 3 Schematic optical layout of beam condenser
systemFig. 1 Schematic section view of the etching chamber, beam converged on the sample surface by moving theposition of the condenser mirror.

124

BL8B2

Electronic Structure of Pentacene Thin Film Converted fromIBM Type Precursor and Vacuum Deposit
R. Sumii 1, A.Takahara 2, K. Kanai 1 , K. Seki1,31
Research Center for Materials Science, Nagoya University, Nagoya 464-8602, Japan2
Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 812-8581,
Japan
3
Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan
contribution from σ and  orbitals. Supplemental
penning ionization electron spectroscopy (PIES)
study indicated that this difference of intensity around3eV comes from the film structure. Similar structure
difference between spin-coat and evaporated film arereported for other compound [2].
Moreover, XPS study at the S2p region also showedthat the adduct part is completely removed from thefilm by heating. These results indicate that the IBM
type pentacene precursor can give high quality
pentacene film from the view point of electronic
structure.

Introduction
Pentacene has high hole mobility, and many studies
have been performed on it. Pentacene film can be
fabricated only by vacuum deposition due to its poor
solubility to solvent. But recent study reported highly
soluble pentacene precursor shown in Fig.1 (IBN typeprecursor), which can be spin-cast to form a film [1].
A retro Diels-Ader reaction caused by heating
converts this precursor to a pentacene. In this study,
we performed a UPS study of the change of thepentacene precursor film to pentacene, showing thatthe same electronic structure are that for a vacuum
deposited film was actually observed.
OCH3150°C Heat

Heatedprecursor

Intensity / arb.unit

NO S

Precursor

Pentacene

Fig. 1 IBM type pentacene precursor

calc

Experimental

Precursor

The pentacene vacuum deposition film wasdeposited on a Au/Si substrate. The pentacene
precursor film was prepared by the spin coating of theprecursor solution of chloroform. Spin coated film
was heated at 150°C under nitrogen atmosphere about
10 minutes. UPS measurements were performed forthese films at BL-8B2 of UVSOR facility.

calc

1086420-2Binding Energy / eVFig. 2 UPS spectra of pentacene precursor film before(bottom) and after (top) heating compared with thetheoretically simulated results.

Results and discussion
Figure 2 shows the UPS spectra of pentacene
precursor film before and after heating. The binding
energy in this figure is given with respect to the Au
Fermi level. We see a clear change between
pentacene precursor and heated film can see at theregion of the HOMO peak. Heated precursor film
show the HOMO peak at 1.5-1.6eV while theprecursor film does not show such peak at this energy.
The simulated spectra by molecular orbital
calculations for these spectra also show good
agreement with the observed spectra.
Figure 3 shows the UPS spectra of vacuum
deposited pentacene film and the heated pentacene
precursor film. These spectra are very similar, exceptthat the peak intensity is a little different at around
0-4eV. This structure is ascribed to the combinedVacuum deposit

Intensity / arb.unit

Heated precursor

1086420-2Binding Energy / eVFig. 3 UPS spectra of vacuum deposited pentacene
film and heated pentacene precursor film.
[1] A. Afzali, C. D. Dimitrakopoulos, T. L. Breen,
J. Am. Chem. Soc. 124 (2002) 8812
[2] H. Ozaki, J. Chem. Phys. 113 (2000) 6361

125

BL4B

X-ray Magnetic Circular Dichroism of Co Nanorods Grown
on Cu(110)-(23)N surface

X.-D. Ma1, T. Nakagawa1,2, F. M. Leibsle3, T. Yokoyama 1,2
1
Department of Structural Molecular Science, The Graduate University for Advanced Studies(Sokendai), Okazaki, Aichi 444-8585, Japan2
Department of Molecular Structure, Institute for Molecular Science (IMS), Okazaki, Aichi
444-8585, Japan3
Department of Physics, University of Missouri at Kansas City, 5110 Rockhill Road,Kansas City, Missouri 64110, U. S. A.
axis is [001] that is perpendicular to the rod axis. The
shape anisotropy does not determine the magnetic
easy axis. Figure 2(b) shows the anisotropic XMCD.
The inset of Fig. 2(b) gives the XMCD normalizedwith the edge jump. The [001] spectrum yields themost intense XMCD among the three directions of[001], [1-10] and [110], confirming that the present
magnetic anisotropy is derived from the anisotropic
spin-orbit interaction. Moreover, one can note that theorbital magnetic moment is rapidly enhanced on theformation of nanorods (<2 ML), as shown in Fig.
2(c).

Magnetic properties of nanorods are hot subjects inrecent years. York et al. [1] discovered selfassembled Co nanorods on Cu(110)-(23)N that are~1 nm thick and well separated with each other up toas much as ~2 ML (monolayer). In the present work,
we have investigated the magnetic properties of theCo nanorods by combining x-ray magnetic circulardichroism (XMCD) with the magneto-optical Kerr
effect (MOKE) measurements.
The experiments were performed at soft X-ray
varied line monochromator station Beamline 4B. The
Co nanorods on Cu(110)-(23)N were grown along
the [1-10] direction. The Co LIII,II-edge XMCD weretaken with the polarization factor of 0.70 at ~90 K.
Figure 1 shows the Auger electron spectra (AES)
and the LEED patterns. The N-KLL AES intensity isfound to be kept constant on Co deposition, implyingthat the N atoms are located always at the surface
even after deposition of Co. On the contrary, theCu-MNN AES is reduced quickly with the Codeposition, suggesting that Cu does not migrate on/in
the Co rods so significantly. On the other hand, theLEED patterns show (16) superstructure as in Figs.
1(d) and 1(e), consistent with the previous STM
observation. This implies successful preparation of
the Co nanrods.
Figure 2(a) depicts the anisotropic magnetization
curves taken by MOKE. The hysteresis accompanied
by remanent magnetization can be seen only along
the [001] direction, implying that the magnetic easy

[1] S.M York et al., Phy. Rev. B 64 (2001) 033411.

Fig. 1 (a) N-KLL and (b) Co, Cu-MNN AES andLEED (c-e) of the Co nanorods on Cu(110)-(23)N.

Fig. 2(a) Magnetic curves taken by MOKE. (b) Co L-edge XMCD normalized with the LII peak, together
with those normalized with the edge jumps in the inset. (c) Ratio of the orbital/spin magnetic moment as afunction of the Co thickness, together with the thermally averaged spin magnetic moment in the inset.

126

BL6B

Terahertz Spectroscopy of Protein Powder

X. Jin 1 , J. Li 1 , M. Shinjo 1 , S. Kimura 2 , H. Kihara1
Department of Physics, Kansai Medical University, 18-89 Uyama-Higashi, Hirakata573-1136, Japan
2UVSOR Facility, Institute for Molecule Science, and School of Physical Sciences, The
Graduate University for Advanced Studies (SOKENDAI), Myodaiji, Okazaki 444-8585, Japan1

10Transmission (a.u.)

Biological polymers are expected to exhibit broadvibrational spectral features in terahertz regime
corresponding to functionally relevant, global andsubglobal collective modes on the picosecondtimescale. This is supported by theoretical moleculardynamics studies and normal mode calculations [1,2].
Due to the strong frequency-dependent terahertz
attenuation of water, these studies should have dry, orpartially hydrated samples. Here we report theterahertz spectra of representative proteins having
various secondary structures, myoglobin, lysozyme,
-synuclein, -lactoglobulin and src-SH3 domain.
All experiments were done at terahertz beam line
BL6B at UVSOR-II. The thickness of the samples wasaround 0.1 mm. The wavenumber range we monitored
was 10-250 cm-1. Each spectrum was accumulated 100times. The final spectra were divided by cell spectrum
in order to subtract influence of the cell. All
measurements were accumulated five times to getgood S/N ratio.
Myoglobin is rich in -helices. Figure 1 shows its
terahertz spectrum. -Lactoglobulin is rich in -sheets(Figure 2). Lysozyme is one of  proteins (Figure 3).
-synuclein does not form any secondary structures
and takes only random coil (Figure 4). Src-SH3 forms
-sheets mostly (Figure 5).
Results show significant difference between
-synuclein and other proteins at around 20 – 130
cm-1.

864
201060110

160210

Wavenumber (cm-1)

Transmission (a. u.)

Fig.2 Terahertz spectroscopy of B lactoglobulin
10864
201060110

160210

Wavenumber (cm-1)

Fig.3 Terahertz spectroscopy of lysozyme

Transmission(a. u.)

10[1] Brooks, B. and Karplus, M. (1983) Proc. Natl.
Acad. Sci. 80: 6571-6575[2] Tama, F., Gadea, F.X., Marquues, O., andSanejouand, Y.H. (2000) Proteins 41: 1-7864201060110160210

Wavenumber (cm-1)

10Transmission(a. u.)

Transmission (a. u.)

Fig.4 Terahertz spectroscppy of A synuclein

864201060110160

Wavenumber (cm-1)

1086420210

Fig.1 Terahertz spectroscopy of myoglobin

1060110160

Wavenumber (cm-1)

210

Fig.5 Terahertz spectroscopy of src-SH3 domain

127