Search

Dynamics of intra-cluster processes induced by femtosecond UV laser radiation in molecular clusters of CF3I and ICF2COF molecules is studied. The measured time constants of the observed reactions are within the range from 1 ps to dozens of picoseconds.

Usingthe femtosecond time-resolved infrared pump–visibleprobe technique, we have measured for the first time the ultrafastdissociation dynamics of [Fe(CO)5]nclusters induced by IR resonant excitation of CO vibrationalmodes in the 5-μm region. Free Fe(CO)5moleculesformed as a result of the cluster dissociation have been ionized bythe femtosecond laser radiation at λ = 400 nm and have beendetected with a time-of-flight mass-spectrometer. The temporal dependenceof the yield of free molecules has been measured under different conditionsof the IR laser excitation. We have proposed a model that describeswell experimental results and makes it possible to calculate the temporalprofile of the cluster temperature in terms of the concept of theevaporative ensemble. The rates of the intramolecular and intraclustervibrational relaxation in [Fe(CO)5]nclusters have been estimated. [ABSTRACT FROM AUTHOR]

Real-time dissociation dynamics induced in [Fe(CO) 5 ] n Xe m 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) 5 molecules. Thus, the formed particles are the origin of signal variations from Xe + and Fe(CO) 5 + ions, which grow on a picosecond time scale. It is concluded that the initial laser excitation of C≡O vibrations in clusterized molecules is followed by the process of cluster dissociation accompanied with the formation of free neutral particles according to the hierarchy of binding energies: weakly bound shells of Xe atoms are evaporated first and much faster than the Fe(CO) 5 molecules from the cluster core. The characteristic times of relaxation processes as well as the cluster temperature were estimated., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)