Study of femtosecond dynamics in vibrationally excited free bis(trifluoromethyl)ketene and metal carbonyl molecules induced by CO bond resonant excitation

Abstract

The dynamics of relaxation processes in free bis(trifluoromethyl)ketene (CF3)2CCO and Fe(CO)5 and Cr(CO)6 metal carbonyl molecules after multiphonon excitation of the C=C=O and C=O vibrations by femtosecond laser infrared radiation was studied. The temporal and spectral dependences of the relaxation of the excited vibrational states were measured. Kinetics with a characteristic decay time of about 5 ps was obtained for (CF3)2CCO molecules. Its behavior is interpreted as a manifestation of the intramolecular relaxation of the excited vibration states of the resonance mode. Kinetic curves with characteristic times of about 250–500 fs were observed for Fe(CO)5 and Cr(CO)6. The behavior of these curves depends on the mutual orientation of the polarizations of the pump and probe pulses.