CO-induced removal of the Pt{1OO}-hex reconstruction studied by RAIRS

Reflection-absorption infrared spectroscopy (RAIRS) has been used to follow the GO-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 x 10(-10) mbar, a band assigned to linear CO on the hex surface starts to appear at 2069 cm(-1). At 2 x 10(-9) mbar a second band assigned to linear CO adsorbed at nucleating (1 x 1) areas is observed at 2080 cm(-1). Between 2 x 10(-8) and 5 x 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 x 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 GO-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.