Infrared line shapes of ethylidyne on the Pt(111) surface

We have measured the temperature dependence of the infrared line shapes of three fundamental vibrations of the ethylidyne species, ≡C–CH3, on the Pt(111) surface. Each of the three line shapes possesses distinctly different properties. The C–C stretch shows the strongest temperature dependence. The...

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Veröffentlicht in:The Journal of chemical physics 1988-09, Vol.89 (6), p.3861-3869
Hauptverfasser: MALIK, I. J, AGRAWAL, V. K, TRENARY, M
Format: Artikel
Sprache:eng
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Zusammenfassung:We have measured the temperature dependence of the infrared line shapes of three fundamental vibrations of the ethylidyne species, ≡C–CH3, on the Pt(111) surface. Each of the three line shapes possesses distinctly different properties. The C–C stretch shows the strongest temperature dependence. The full width at half-maximum (FWHM) varies quadratically with temperature from 6 cm−1 at 82 K to 10 cm−1 at 350 K. The frequency of the C–C stretch shows a linear shift from 1125 cm−1 at 82 K to 1117 cm−1 at 350 K. The symmetric C–H stretch shows a temperature independent frequency of 2883 cm−1 and only a small change in full width from 4.1 cm−1 at 82 K to 5.1 cm−1 at 300 K. The symmetric CH3 bend has an unusually narrow full width of 1.2 cm−1 at 82 K which increases to 2.4 cm−1 at 350 K while its frequency remains constant within the experimental error. The results are discussed in terms of current theories of vibrational line broadening for molecules adsorbed on metal surfaces.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.454861