Real-time observation of ultrafast ionization and fragmentation of mercury clusters.

We report on time-resolved multiphoton ionization and fragmentation dynamics of free Hg _n-clusters ( n≤110) with femtosecond laser pulses. Already at laser intensities of 10¹¹ W/cm² we observe prompt formation of singly, doubly, and triply charged Hg _n clusters. In pump-probe experiments short-time (0–5 ps) oscillatory modulations of the transient Hg _n ⁺ and Hg _n ²⁺ signals are observed which indicate an intermediate state dynamics common to all observed cluster sizes and charge states. Long-time (0–200 ps) transient ionization signals show caged dissociation and recombination chromophore dynamics. [ABSTRACT FROM AUTHOR]