CO ADSORPTION ON ULTRATHIN MGO FILMS GROWN ON A MO(100) SURFACE - AN IRAS STUDY

CO adsorption on MgO ultrathin films grown on a Mo(100) surface is studied using infrared reflection absorption spectroscopy (IRAS), CO adsorbed on 7 ML of MgO shows a stretch frequency at 2178 cm-1 which is blue-shifted relative to that of gas-phase CO (2143 cm1). This blue-shift is believed to arise from electron charge donation from the CO5-sigma orbitals to the MgO surface. The heat of adsorption of CO on 7 MI, of MgO is estimated to be 9.9 kcal/mol using an isothermal adsorption method. CO adsorbed on the MgO thin films desorbs between 100 and 180 K, as indicated by temperature-programmed desorption.