Probing the structure of metal cluster-adsorbate systems with high-resolution infrared spectroscopy

High-resolution infrared Laser spectroscopy was used to obtain rotationally resolved infrared spectra of adsorbate-metal complexes. The method involve s forming the bare metal clusters in helium nanodroplets and then adding a molecular adsorbate (HCN) and recording the infrared spectrum associated wi th the C-H stretching vibration. Rotationally resolved spectra were obtaine d for MCN-Mg-n (n = 1 to 4). The results suggest a qualitative change in th e adsorbate-metal cluster bonding with cluster size.