Mode-specific intermolecular vibrational energy transfer. I. Phenyl selenocyanate and deuterated chloroform mixture

Vibrational energy transfer from the first excited state (2252 cm-1) of the C-D stretch of deuterated chloroform (DCCl3) to the 0-1 transition (2155 cm-1) of the CN stretch of phenyl selenocyanate (C₆ H₅ SeCN) in their 1:1 liquid mixture was observed with a pump/probe two-color two dimensional infrared spectroscopic technique. The mode-specific energy transfer can occur mainly because of the long vibrational lifetime of the CN stretch first excited state (∼300 ps) and the relatively strong hydrogen-bond between the C-D and CN (calculated H-bond formation energy in gas phase ∼-5.4 kcal/mol). The mode-specific energy transfer is relatively low efficient (only ∼2%), which is mainly because of the relatively short vibrational lifetime (∼9 ps) of the C-D stretch first excited state and the big donor/acceptor energy mismatch (97 cm-1) and the slow transfer kinetics (1/ kCD→CN =330 ps).