CO-induced removal of the Pt{100}-hex reconstruction studied by RAIRS

Abstract

Reflection–absorption infrared spectroscopy (RAIRS) has been used to follow the CO-induced removal of the Pt{100}-hex surface reconstruction at 387 K and a range of ambient CO pressures. After ca. 3 min exposure at 5 × 10–10 mbar, a band assigned to linear CO on the hex surface starts to appear at 2069 cm–1. At 2 × 10–9 mbar a second band assigned to linear CO adsorbed at nucleating (1 × 1) areas is observed at 2080 cm–1. Between 2 × 10–8 and 5 × 10–8 mbar, the intensity of the CO absorption band increases dramatically and its frequency shifts to 2086 cm–1, consistent with linear CO on the extended (1 × 1) surface. Visual LEED observation confirms that this dramatic change of the spectrum is caused by the lifting of the hex reconstruction. In this way the initiation of the CO-induced removal of the Pt{100}-hex reconstruction is observed at CO coverages as low as ca. 0.01 monolayers (ML) by RAIRS. Recent room-temperature RAIRS data of Martin, Gardner and Bradshaw are reassigned on the basis of the present data.