SERS-active sites on various copper substrates

Autor: Andreas Bruckbauer, M. Sinther, Andreas Otto, A. Goussev, C. Siemes, Annemarie Pucci
Rok vydání: 2001
Předmět:
Zdroj: Journal of Raman Spectroscopy. 32:231-239
ISSN: 1097-4555
0377-0486
DOI: 10.1002/jrs.692
Popis: The wavenumbers of the Raman bands of ethylene adsorbed on Cu in ultra-high vacuum depend on the surface structure of the copper substrate. Thus it is possible to differentiate between ethylene adsorbed at Cu(110) sites, Cu(111) sites and surface defect sites of unknown configuration. These latter are the ‘SERS-active sites.’ Only when these sites are annealed does the distance dependence of SERS follow the expectations from the electromagnetic model of SERS. In the presence of the SERS-active sites, also the signal of ethylene at (111) sites shows a ‘first layer effect.’ Ethylene adsorbed on cold-deposited copper films shows strong infrared absorption at the same wavenumber as the ethylene at SERS-active sites in Raman scattering, irrespective of the Raman–infrared exclusion rule for the free centrosymmetric ethylene molecule. This raises the possibility that SERS-active sites are also infrared-active sites. The SERS-active sites at stepped Cu surfaces decorated by 3 nm of cold-deposited copper anneal below 200 K, whereas they prevail beyond 400 K on Cu island films. Copyright © 2001 John Wiley & Sons, Ltd.
Databáze: OpenAIRE
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