Real-time observation of ultrafast ionization and fragmentation of mercuryclusters

We report on time-resolved multiphoton ionization and fragmentation dynamic s of free Hg-n-clusters (n less than or equal to 110) with femtosecond lase r pulses. Already at laser intensities of 10(11)W/cm(2) we observe prompt f ormation of singly, doubly, and triply charged Hg, 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 stat e dynamics common to all observed cluster sizes and charge states. Long-tim e (0-200 ps) transient ionization signals show caged dissociation and recom bination chromophore dynamics.