Electron energy loss spectroscopy (EELS) of CH3NH2 adsorbed on Ni(100), Ni(111), Cr(100), and Cr(111)

Adsorbed CH3NH2 has been studied on Ni(100), Ni(111), Cr(100), and Cr(111) at 300 K using electron energy loss spectroscopy. The vibrational spectra indicate that molecular CH3NH2 exists on all four surfaces with bonding through the nitrogen lone pair, although a substantial amount of dissociation also occurs on the chromium surfaces. Approximately one monolayer of surface species is the stable coverage on each surface at 300 K. The possible existence of coadsorbed dissociation products CH/sub x/ and NH/sub x/ is discussed. The CN stretch is anomalously broad on Ni (100) and Ni(111) but not detectably broadened on Cr(100), indicating a strong sensitivity of this bond to interactions with the Ni surfaces. A multiplicity of sites is indicated on Cr(111) by the breadth of all the peaks. The loss spectra exhibit striking intensity differences, which can be attributed partly to impact scattering and partly to intrinsic differences in the interaction of CH3NH2 with the different surfaces. A model explaining the linewidth and intensity differences is proposed