NH2 FORMATION IN THE REACTION OF H-ADS WITH NO ON THE PT(100)-(1X1) SURFACE

The reaction of a saturated layer of H-ads with NO on the unreconstruc ted Pt(100)-(1 x 1) surface at 300 K has been studied by high-resoluti on electron energy loss spectroscopy (HREELS) and temperature programm ed reaction spectroscopy (TPRS). The NH2ads species is produced as an intermediate of the reaction. The vibrational losses of NH2ads at 480 cm(-1) (v(Pt-NH2) stretching), 825 cm(-1) (omega(NH2) wagging), 1450 c m(-1) (delta(NH2) scissors), 3298 cm(-1) (v(s)(NH2) symmetric stretchi ng) and 3388 cm(-1) (v(as)(NH2) asymmetric stretching) are observed. T he hypothesis of the formation of NH2(ads) is supported by modeling by means of the Wilson GF matrix method and the simplest valence force a pproximation. The reaction of an adlayer consisting of a 1:1 mixture o f H-ads/D-ads with NO produces an isotopic mixture of NH2ads ND2ads an d NHDads. The vibrational spectra of NH2ads and its isotopic counterpa rts ND2ads and NHDads have been discussed in detail. Based on the deta iled analysis of the vibrational modes, the NH2ads species is suggeste d to occupy the bridge adsorption place with C-2v symmetry. (C) 1997 E lsevier Science B.V.