Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 18: Adsorption an Oberflächen I

O 18.8: Vortrag

Dienstag, 9. März 2004, 13:00–13:15, H38

SERS and infrared spectra of NO on cold-deposited Cu — •Matthias Lust¹, Andreas Priebe¹, Andreas Otto², and Annemarie Pucci¹ — ¹Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, D-69120 Heidelberg, Germany — ²Lehrstuhl für Oberflächenwissenschaft, Universität Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany

SERS-spectra of nitric oxide (NO) on cold-deposited (<50K) Cu show the reduction of NO. Depending on exposure we observe two different strong dinitrogen stretch bands, vibrations of nitrous oxide (N₂O), and a broad band of vibrations of atomic oxygen-copper vibrations, but no signal of NO.

For FTIR spectroscopy at an incident angle of 80^o, the copper samples were similarly prepared by deposition and exposure at low temperature. In contrast to SERS-measurements the IR spectra show a strong signal of NO but also one dinitrogen band and the nitrous oxide signals could be seen.

We show several experiments that should help to understand the different results of SERS- and IR spectroscopy. In principal, the difference in the observed species may be due to a photochemical reaction during the 647.1 nm laser irradiation and thereby leading to a complete reduction of NO during the acquisition of SER spectra or due to heating up of the sample, or a yet unknown effect of SERS. At present these hypotheses are under investigation.