Infrared reflection-absorption spectroscopic study on the adsorption structures of acrylonitrile on Ag(111) and Ag(110) surfaces

Infrared reflection-absorption spectra in CN stretching, CH2 out-of-plane w agging and CH2 twisting vibration regions were measured for acrylonitrile ( CH2-CHCN) exposed to Ag(111) and Ag(110) in increasing amounts at 77 K. The adsorbate on Ag(lll) takes on a series of discrete adsorption states; i.e. , an isolated state, associated states, and ordered and amorphous multilaye r states. The adsorbate on Ag(110) at lower exposures is in a state with th e CN group weakly coordinated to a silver atom (or silver atoms). The adsor bate on Ag(110) takes the associated state and the amorphous multilayer at larger exposures. On raising the temperature to 96 K, the amorphous states on both Ag(lll) and Ag(110) are converted to the ordered multilayer. The de sorption temperature of the ordered multilayer is below 99 K for Ag(110), w hile the temperature is above 107 K for Ag(lll); the result indicates the e ffect of the surface morphology on the stability of the ordered state. (C) 1999 Elsevier Science B.V. All rights reserved.