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B4.5.1

Oriented Growth of Model Molecules of Polyethylene and Poly(tetrafluoroethylene) (n-C44H90 and n-C24F50) and Angle-resolved UPS Study of Their Intramolecular Energy Band Dispersion (E=E(k)) Relation Daisuke Yoshimura1, Takayuki Miyamae2, Sinji Hasegawa3, Yukinobu_Hosoi4, Yoko Sakurai4, Masato Yamamoto5, Hisao Ishii6, Yukio Ouchi4, Nobuo Ueno7, and Kazuhiko Seki1 1Research Center for Materials Science, Nagoya University, Furocho, Chikusa-ku, Nagoya 464-8602, Japan 2

Advanced Institute of Science and Technology,

3

Institute for Molecular Science, Okazaki 444-8585, Japan

4

Department of Chemistry, Graduate School of Science, Nagoya University,

Furocho, Chikusa-ku, Nagoya 464-8602, Japan 5

Department of Chemistry, College of Arts and Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo

142-8555, Japan 6

Research Institute of Electrical Communication, Katahira, Aoba-ku, Sendai 980-8577, Japan

7

Department of Materials Engineering, Faculty of Engineering, Chiba University,

Yayoicho, Inage-ku, Chiba 263-8522, Japan

ABSTRACT We report on the recent progress of our continued effort for the preparation and characterization of well oriented films of tetratetracontane (n-C44H90) and perfluorotetracosane (n-C24F50 ), which are good model molecules of fundamental polymers, polyethylene (CH2)n and poly(tetrafluoroethylen) (CF2)n, vacuum-deposited on metal surfaces. When the surface of the metal substrate was oxidized, the deposited chain molecules are aligned with their molecular axes vertically standing on the surface, while they lie flat on the surface when atomically clean Cu(100) surface was used. In the case of n-C44H90 on Cu (100), low-energy electron diffraction (LEED) studies revealed that the molecules were also azimuthally aligned with the chain axis almost parallel with the and axis, and infrared reflection-absorption spectroscopy (IR-RAS) enabled detailed studies of the film structure at increasing film thickness._By applying the technique of angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) to these flat-lying molecules, the intramolecular energy-band dispersion relation could be determined, The results agreed well with the results deduced from the previous work using vertically standing molecules assuming an inner potential V0. of –5 eV, confirming the validity of the estimation of V0.

Excellent agreement was found between the observed

and simulated spectra using the independent-atomic-center (IAC) approximation.

Also the value of the vacuum

level shift by molecular deposition was deduced for TTC/Cu(100) system to be – 0.3 eV. As for n-C24F50, the E(k) relation deduced in our previous study using vertically standing molecules showed discrepancy with band calculations. The detailed reexamination of the experimental data using IAC calculations for the previous report gave more realistic estimation of V0, and the newly deduced E (k) relation using this data showed good correspondence with theoretical band calculations, thus removing the difficulty in the previous work.