Surface Chemistry of HNCO and NCO on Pd(100)

The interaction of HNCO with Pd(100) has been studied with reflection absorption infrared spectroscopy. Following the adsorption of HNCO at 100 K, a fraction of the adsorbed HNCO desorbs at 115−125 K and another part dissociates at 120−140 K yielding adsorbed H and NCO species. NCO locates in top-site position having significant lateral repulsive interaction between them. On clean surface, the NCO species was found to decompose readily to adsorbed CO and N on warming to 300 K. Preadsorbed oxygen atoms resulted in the significant stabilization of NCO; the asymmetric stretch of it was detected up to 380 K. Neither NCO nor HNCO were identified in the NO + CO reaction even at high pressure (1−10 mbar) and at elevated temperature (500−650 K). The presence of hydrogen did not help the formation of this species.