Regensburg 2002 – scientific programme
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SYBM: Physik biologischer Materie
SYBM 401: Physics of biological matter: Poster
SYBM 401.19: Poster
Tuesday, March 12, 2002, 18:00–19:30, H37
Vibrational Properties of Cytosine Films Grown onto H-Si(111) Surfaces — •S. Silaghi, G. Salvan, C. Himcinschi, A. Das, A. Yu. Kobitski, C. Crainic, M. Friedrich, T.U. Kampen, and D.R.T. Zahn — Institut für Physik, Technische Universität Chemnitz, 09107 Chemnitz, Germany
Raman and Infrared spectroscopy are applied for the optical characterization of the DNA base cytosine (C4H5N3O). Films with different thicknesses were grown by Organic Molecular Beam Deposition on H-Si(111) surfaces under Ultra High Vacuum conditions. Raman spectra were recorded in a backscattering geometry in a micro-Raman configuration using the 514.5nm (2.41eV) and 488nm (2.54eV) lines of an Ar+ laser (P=1mW) for excitation. Appearance of external modes, i.e. phonons, indicates the crystallinity of cytosine films. IR measurements were recorded using s and p polarized light for an incidence angle of 60o revealing a polarization dependence of vibrational bands related to CH and NH2 deformations in cytosine films. No changes in the conformational structure of the cytosine molecule in films were observed. The experimentally observed internal vibrational modes of the cytosine molecule are in good agreement with calculated ones using Gaussian 98 calculations with a B3LYP/6-31G(d) basis set.