SITE SWITCHING AND SURFACE RESTRUCTURING INDUCED BY NO ADSORPTION ON PT(110)

We present the first infrared vibrational study of the adsorption of N O on Pt(110) over a wide range of temperatures. Adsorption is strongly dependent on both temperature and coverage, with many different speci es being formed on the surface. Under all conditions, site switching i s observed during NO adsorption: at low coverages bridge-bonded specie s are formed on the surface, and at very high coverage NO switches to on-top sites. Other species, not previously reported, are also observe d, depending on both adsorption temperature and coverage. The clean Pt (110) surface exhibits a (1 x 2) surface reconstruction which can be l ifted by the adsorption of NO (or CO), depending on surface temperatur e and adsorbate coverage. In contrast to CO adsorption, the on-top sur face species shows different frequencies on the(1 x 2) and(1 x 1) surf ace phases, and this is deployed to identify the temperature at which the reconstruction begins to lift.