A comparison of single-, double-, triple-bonded and aromatic CN compounds on Pd(111) and (100): II. HREELS and TDS of HCN on Pd(111)

Abstract

On Pd(111) a single chemisorbed HCN surface species with a CN stretch frequency of 191 meV, corresponding to HCN, is observed over the complete temperature range measured, from 100 K up to the desorption temperature of chemisorbed HCN at 425 K. CN ads remains at higher temperature. An imine-like η 2(C, N) bond, where the HCN angle is less than 180° is probable. At low temperature ( <140 K) HCN forms multilayers of a hydrogen bonded solid with v(CN), v(CH) and γ(HCN) at 257, 388 and 102 meV respectively. Dimerization and catamerization of adsorbed HCN may be monitored using the bulk libration at 26 meV and the C-H stretching mode. Strong multiple scattering effects are observed in solid HCN films.