COLL 144

Density functional theory (DFT) calculations and measurements using reflection absorption infrared spectroscopy have been used to characterize the following three aminocarbynes on Pt(111): CNH₂, CNHCH₃, and CN(CH₃)₂. Gaussian 98 was used with the B3LYP functional and a 6-311G** basis set along with effective core potentials for the Pt atoms. The surface was modeled with metal clusters containing one to nine Pt atoms representing different adsorption sites. The calculated frequencies and relative intensities were used to simulate spectra for direct comparison with the experimental spectra. The best results for each aminocarbyne were obtained for a two-Pt atom model representing bonding at a two-fold bridge site. It was found that better agreement between experimental and simulated spectra could be achieved more effectively by increasing the size of the basis set used for the adsorbate atoms than by increasing the size of the metal cluster.