Picosecond spectroscopy of van der Waals clusters

Citation

Willberg, Dean Michael (1994) Picosecond spectroscopy of van der Waals clusters. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/605h-j578. https://resolver.caltech.edu/CaltechETD:etd-04042008-110156

Abstract

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This thesis presents pump/probe picosecond spectroscopic investigations of the dynamics of van der Waals clusters. The first phase of these investigations was the construction of a laboratory specifically designed for van der Waals cluster research consisting of a molecular beam apparatus and a two-color picosecond laser system. It is possible to perform both time resolved laser induced fluorescence (LE), and multi-photon ionization (MPI) experiments in this laboratory. A description of the construction and operation of the laboratory, focusing on the laser system, is presented. A full account of the real-time studies of the vibrational predissociation of [...] clusters where [...] is given. The first set of experiments described is the measurement of the rates of vibrational predissociation for [...] clusters. The results for [...] are compared with a number of theoretical models of vibrational predissociation, specifically focusing on the dependence of the rates on the initially prepared vibrational state of the cluster. The results for the [...] cluster are described in terms of the competition between two relaxation channels: vibrational predissociation of the van der Waals cluster, and electronic predissociation of the [...] moiety. The second set of experiments are the analogous measurements of the rates of vibrational predissociation of [...] clusters. These results are compared with the [...] results, as well as with lifetime estimates available from high resolution spectroscopy. The final chapter in this series describes our investigation of vibrational predissociation and intramolecular vibrational energy relaxation in [...] clusters. The dynamics of these larger clusters are inherently more complicated than when n = 1, however, a quantitative model for the fragmentation of n = 2 clusters is presented. This thesis also presents a preliminary description of an ongoing MPI experiment on the dynamics of t-stilbene clusters.

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