Applied Surface Science, Vol.169, 282-286, 2001
Inner shell excitation and dissociation of condensed formamide
Carbon and nitrogen K-shell excitation and dissociation of condensed formamide at 96 K were studied by near edge X-ray absorption fine structure (NEXAFS) recorded by total electron yield (TEY), total ion yield (TN) and photon-stimulated desorption (PSD) yield of H+ measurements. It was found that electronic transitions from the C Is or the N Is to the sigma* (C-FI and/or N-H) enhanced ion yields of H+ from the C-H and/or N-H functional groups. This selective dissociation indicates that the corresponding unoccupied molecular orbital has an antibonding character of the C-H and/or N-H. To investigate the molecular orientation of condensed formamide, incidence-angle-dependent TEY-NEXAFS spectra were measured. The CNO plane of the adsorbed formamide molecule is determined to be tilted away from the surface by an averaged angle of about 42 degrees.