IR spectroscopy of adsorbed dinitrogen: a sensitive probe of defect sites on Pt(111)

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Bibliographic Information

IR spectroscopy of adsorbed dinitrogen: a sensitive probe of defect sites on Pt(111). Arumainayagam, Christopher R.; Tripa, C. Emil; Xu, Jiazhan; Jr, John T. Yates. Department of Chemistry, Wellesley College, Wellesley, MA, USA. Surf. Sci. (1996), 360(1-3), 121-127. CODEN: SUSCAS ISSN: 0039-6028. Journal written in English. CAN 125:178211 AN 1996:448190 CAPLUS (Copyright 2001 ACS)

Abstract

Fourier transform IR reflection absorption spectroscopy (FT-IRAS) was used to probe the non-dissociative adsorption of N₂ on an atomically clean Pt(111) single crystal. In contradiction to a previous IRAS study of nitrogen adsorption on a Pt(111) foil at 120 K, no nitrogen IR (IR) band was obsd. on a fully annealed Pt(111) surface at 90 K. Following Ar⁺ ion bombardment, adsorption of nitrogen at 90 K produces an intense IR band at .apprx.2222cm^-1 attributed to the N-N stretching mode of mol. nitrogen adsorbed on defect sites produced by ion bombardment. Annealing the Ar⁺ ion sputtered surface to a temp. above .apprx.750 K completely suppresses the adsorption of nitrogen at 90 K. Based on these and other results, it is postulated that nitrogen adsorbs at 90 K mainly on monovacancies on platinum. It is suggested that this specific adsorption occurs by sigma donation from nitrogen to the base of monovacancy sites which possess a low d-electron d. compared to surface Pt atoms.