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.

© 2022 The Authors. Published by American Chemical Society.