EXCIMER FORMATION DYNAMICS IN PURE AND MIXED NAPHTHALENE CLUSTERS

The excited-state dynamics of the pure naphthalene clusters and of the mixed clusters involving two naphthalenes solvated with durene have been investigated as a function of the excess vibrational energy of the initially excited clusters. All of the clusters studied exhibit excimer fluorescence, depending strongly on the excess vibrational energy and on the solvation number. The isomerization rate has been measured by detecting a buildup in the excimer fluorescence and used as a probe of the cluster geometry. The trimer requires an excess energy of 870 cm-1 to promote the excimer formation with a rise time of 32 ns, suggesting a structurally less favorable process, The dimer and tetramer undergo rapid isomerization at much lower energies. The solvent addition is found to impede excimer formation, due to geometry restriction. The singly solvated cluster exhibits an excimer evolution time as slow as 60 ns.