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Title: Orientation of pentacene molecules on SiO{sub 2}: From a monolayer to the bulk

Abstract

Near edge x-ray absorption fine structure (NEXAFS) spectroscopy is used to study the orientation of pentacene molecules within thin films on SiO{sub 2} for thicknesses ranging from monolayers to the bulk (150 nm). The spectra exhibit a strong polarization dependence of the {pi}{sup *} orbitals for all films, which indicates that the pentacene molecules are highly oriented. At all film thicknesses the orientation varies with the rate at which pentacene molecules are deposited, with faster rates favoring a thin film phase with different tilt angles and slower rates leading to a more bulklike orientation. Our NEXAFS results extend previous structural observations to the monolayer regime and to lower deposition rates. The NEXAFS results match crystallographic data if a finite distribution of the molecular orientations is included. Damage to the molecules by hot electrons from soft x-ray irradiation eliminates the splitting between nonequivalent {pi}{sup *} orbitals, indicating a breakup of the pentacene molecule.

Authors:
; ; ; ;  [1];  [2];  [2]
  1. Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20991250
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 126; Journal Issue: 15; Other Information: DOI: 10.1063/1.2717161; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION; ABSORPTION SPECTROSCOPY; CRYSTALLOGRAPHY; FINE STRUCTURE; IRRADIATION; ORIENTATION; PENTACENE; POLARIZATION; SEMICONDUCTOR MATERIALS; SILICON OXIDES; SOFT X RADIATION; SPECTRA; THIN FILMS; X-RAY SPECTROSCOPY

Citation Formats

Zheng, Fan, Park, Byoung-Nam, Seo, Soonjoo, Evans, Paul G., Himpsel, F. J., Materials Science Program University of Wisconsin, Madison, Wisconsin 53706 and Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin 53706, and Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706. Orientation of pentacene molecules on SiO{sub 2}: From a monolayer to the bulk. United States: N. p., 2007. Web. doi:10.1063/1.2717161.
Zheng, Fan, Park, Byoung-Nam, Seo, Soonjoo, Evans, Paul G., Himpsel, F. J., Materials Science Program University of Wisconsin, Madison, Wisconsin 53706 and Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin 53706, & Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706. Orientation of pentacene molecules on SiO{sub 2}: From a monolayer to the bulk. United States. doi:10.1063/1.2717161.
Zheng, Fan, Park, Byoung-Nam, Seo, Soonjoo, Evans, Paul G., Himpsel, F. J., Materials Science Program University of Wisconsin, Madison, Wisconsin 53706 and Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin 53706, and Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706. Sat . "Orientation of pentacene molecules on SiO{sub 2}: From a monolayer to the bulk". United States. doi:10.1063/1.2717161.
@article{osti_20991250,
title = {Orientation of pentacene molecules on SiO{sub 2}: From a monolayer to the bulk},
author = {Zheng, Fan and Park, Byoung-Nam and Seo, Soonjoo and Evans, Paul G. and Himpsel, F. J. and Materials Science Program University of Wisconsin, Madison, Wisconsin 53706 and Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin 53706 and Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706},
abstractNote = {Near edge x-ray absorption fine structure (NEXAFS) spectroscopy is used to study the orientation of pentacene molecules within thin films on SiO{sub 2} for thicknesses ranging from monolayers to the bulk (150 nm). The spectra exhibit a strong polarization dependence of the {pi}{sup *} orbitals for all films, which indicates that the pentacene molecules are highly oriented. At all film thicknesses the orientation varies with the rate at which pentacene molecules are deposited, with faster rates favoring a thin film phase with different tilt angles and slower rates leading to a more bulklike orientation. Our NEXAFS results extend previous structural observations to the monolayer regime and to lower deposition rates. The NEXAFS results match crystallographic data if a finite distribution of the molecular orientations is included. Damage to the molecules by hot electrons from soft x-ray irradiation eliminates the splitting between nonequivalent {pi}{sup *} orbitals, indicating a breakup of the pentacene molecule.},
doi = {10.1063/1.2717161},
journal = {Journal of Chemical Physics},
number = 15,
volume = 126,
place = {United States},
year = {Sat Apr 21 00:00:00 EDT 2007},
month = {Sat Apr 21 00:00:00 EDT 2007}
}