Femtosecond infrared coherent excitation of liquid phase vibrational population distributions (v>5)

Femtosecond mid-infrared excitation of room temperature W(CO)6/n-hexane solutions resonant with the T1u CO-stretching mode transfers vibrational population to at least v=6. The population distribution in levels v=0 to v=5 was measured by transient infrared absorption spectroscopy. Resonance frequencies, anharmonic shifts and spectral broadening of observed ladder transitions were also characterized. Populating v=6 deposits ∼12 000 cm−1 in a single mode which is close to the dissociation energy of one W–C bond. These results constitute a significant step toward initiation and ultimate control of condensed phase, mid-infrared induced ground state reactions relevant to practical synthetic transformations.