Spectroscopy On Mass-Selected Neutral Clusters: Femtosecond Dynamics Of The Ground State Of Ag-N

We demonstrate a novel scheme for the investigation of the ultrafast dynamics of neutral mass‐selected molecules and clusters applying it to Agn clusters. It relies on the creation of neutral particles at a certain time by detaching the electron from the corresponding mass selected anions with an ultrashort laser pulse, and ionizing them by a second laser pulse after a well defined time delay Δt. The intensity of the positive ion signal as a function of the delay interval between the fs laser pulses is a measure of the time‐dependent Franck‐Condon factor for photoionization of a neutral molecule which was prepared by a vertical detachment process from a low lying vibrational state of the negative ion. In this way, we probe the vibrational motion in the ground state of the neutral starting from the equilibrium geometry of the anion. As the electronic ground state is usually not predissociated, we are able to follow the dynamics of the system without perturbation by fragmentation. In this contribution we wi...