Ultrafast Dissociation Dynamics Induced in [Fe(CO)] Xe Mixed Clusters by Resonant Femtosecond Infrared Laser Radiation.

Real-time dissociation dynamics induced in [Fe(CO)] Xe mixed molecular clusters by femtosecond IR radiation in the 5 μm region was studied for the first time by means of time-resolved methods based on resonant excitation of C≡O vibrations in the molecular core of the cluster and photoionization probing (λ = 400 nm) of its decay products. It was found that IR-excited clusters in the initially cold particle beam are heated and dissociated as a result of relaxation processes, giving rise to free neutral Xe aggregates and Fe(CO) molecules. Thus, the formed particles are the origin of signal variations from Xe and Fe(CO) ions, which grow on a picosecond time scale.

IVR Dynamics of Vibrational Levels of the ν Mode in (CF)C═C═O Molecules Excited by Resonant IR Femtosecond Radiation.

The intramolecular dynamics of vibrational levels (up to v = 5) of the ν mode in the (CF)CCO molecule that is induced by a multiphoton selective excitation of this mode by resonant femtosecond IR radiation has been studied. The times of intramolecular vibrational energy redistribution (IVR) from each vibrational level to remaining molecular modes have been determined. In accordance with theoretical predictions, a decrease in the IVR time with increasing quantum number v has been observed for the first time.

Ultrafast dissociation dynamics of [Fe(CO)5](n) clusters induced by femtosecond IR radiation.

Using the femtosecond time-resolved infrared pump-visible probe technique, we have measured for the first time the ultrafast dissociation dynamics of [Fe(CO)5]n clusters induced by IR resonant excitation of C≡O vibrational modes in the 5-μm region. Free Fe(CO)5 molecules formed as a result of the cluster dissociation have been ionized by the femtosecond laser radiation at λ = 400 nm and have been detected with a time-of-flight mass-spectrometer. The temporal dependence of the yield of free molecules has been measured under different conditions of the IR laser excitation.

Intramolecular vibrational dynamics in free polyatomic molecules with C═O chromophore bond excited by resonant femtosecond IR laser radiation.

In nine polyatomic molecules, we have studied the intramolecular redistribution of vibrational energy from chromophore C═O group excited by a resonant femtosecond IR laser radiation at a wavelength of ∼5 μm. All experiments have been performed in the gas phase using the IR-IR pump-probe technique in combination with the spectral analysis of the probe radiation. For molecules with one C═O end group, characteristic times of intramolecular vibrational redistribution (IVR) lie in the range between 2.