Spectroscopic characterization of vinylidene formed from isomerization of acetylene on Pd(111)

Abstract

Acetylene on the Pd(111) surface was studied with reflection absorption infrared spectroscopy (RAIRS). Upon adsorption of acetylene at 90 K, no vibrational peaks are observed. However, after annealing the surface to 300 K, peaks at 1095 and 1327 cm−1 due to the CC stretch and CH3 deformation modes of ethylidyne (CCH3) are observed. These peaks are accompanied by a peak at 1425 cm−1 that is assigned to the CC stretch mode of vinylidene. The experimental spectrum is in good agreement with a simulated spectrum from DFT calculations of vinylidene on a Pd19 cluster model of the Pd(111) surface.