CO on Ni(100): observation of a high-frequency IR band at 2200 cm−1

Abstract

Abstract The infrared spectrum of CO adsorbed on Ni(100) displays an additional high-frequency band at about 2200 cm −1 co-existing with the IR bands due to terminal and bridging CO at temperatures below 130 K. The 2200 cm −1 band is attributed to the internal stretching mode of CO molecules weakly bonded to those Ni surface atoms which are charged due to bonding to subsurface oxygen. The considerable blue-shift of 70 cm −1 with respect to the vibration frequency of free CO is assumed to arise from a Stark effect.