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IR spectroscopy of adsorbates on ultrathin metal films
Author(s) -
Pucci Annemarie
Publication year - 2005
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200541131
Subject(s) - raman spectroscopy , infrared spectroscopy , materials science , spectroscopy , absorption (acoustics) , metal , absorption spectroscopy , infrared , dipole , surface roughness , molecule , monolayer , conductivity , molecular vibration , analytical chemistry (journal) , chemistry , nanotechnology , optics , composite material , physics , organic chemistry , quantum mechanics , metallurgy , chromatography
Metal films with thickness in the nanometer range are optically transparent. With IR transmittance spectroscopy the in‐plane film conductivity with its correlation to the film‐growth process can be studied without electrical contacts and, on metal‐island films, adsorbate vibrations can be observed because of surface enhanced IR absorption (SEIRA). Their analysis enables insight into the adsorbate‐metal bonding and therefore gives information on the available adsorption sites and the crystalline facets correlated to. As in IR reflection absorption spectra dipole–dipole interaction of molecules on different sites modifies the vibration lines according to the degree of disorder (“atomic roughness”). Depending on that roughness IR spectra of adsorbate vibrations may be further modified because of their interaction with electronic excitations of the film. So, the limited facet size on cold‐condensed metal films leads to additional IR activity: Raman lines of certain centrosymmetric adsorbate molecules (C 2 H 4 ) are observed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)