Vibrational energy redistribution in Cp *Ir(CO) 2 (Cp *=η 5-pentamethylcyclopentadienyl) studied by broadband transient infrared spectroscopy

Abstract

Picosecond vibrational energy dynamics involving the symmetric (2020 cm −1 and asymmetric (1953 cm −1) CO-stretching modes of Cp *Ir(CO) 2 in room temperature n-hexane is measured using mode specific infrared excitation followed by broadband infrared multichannel probing to generate a transient spectrum. The recovery of the transient bleaching and absorption bands, following 2020 or 1953 cm −1 excitation, yields a v=1 CO-stretching lifetime T 1=28±7 (1σ) ps. The transitions from v=1 vibrational states give rise to new absorption features in the transient spectra at 2008, 1994, 1941 and 1930 cm −1. The time evolution of these absorptions monitors rapid energy redistribution and equilibration (<10 ps) between the symmetric and asymmetric CO-stretching modes prior to ground state recovery.