Knowledge Bank

Several hydrogen bonded clusters of phenol with water, methanol and phenol were examined by spectral hole burning (SHB). The ground state is depopulated persistently on the time scale of the experiment by a tunable dye laser (burn laser). After a variable time delay (400 to 800 ns) the population of the ground state level is probed by a second dye laser. If probe and burn laser share a common ground state level, the fluorescence caused by the probe later is decreased [1]. Because of cluster and state selectivity of spectral hole burning, several intermolecular vibrations of Phenol. $(H2O)3$ could be assigned for the first time[2]. In opposite to Resonance Enhanced multiphoton Ionisation with time flight detection (REMPI-TOF) fragmentation of the clusters does not perturb the spectrum Different conformers of one cluster size can be distinguished by SHB. The phenol dimer provides an interesting example of a cluster with tow closely neighbouring elcectronically excited states. These excited states belong to the donor and the acceptor chromophore respectively. Spectral hole burning provides new insights in the vibrational structure of this cluster and in dynamic process between the different potential surfaces.