Electronic spectroscopy of some metal-containing free-radicals

Laser-induced fluorescence (LIF) spectroscopy has been used to probe the properties of some metal-containing free-radicals. These radicals were formed using three different techniques; fragmentation through electric discharge, laser ablation and laser photolysis and were studied in a supersonic jet expansion.;A dispersed fluorescence spectroscopic study of the zinc-monoethyl free radical was performed. From this work vibrational frequencies, particularly of the Zn-C stretching and the Zn-C-C bending modes, have determined for both the X˜ and A states. In addition several peaks in the excitation spectrum reported by Povey et al. (22500--24000 cm-1) have been assigned.;Recently Professor T.A. Miller and co-workers at Ohio State University recorded rotationally-resolved LIF spectra of ZnC2H5 in the 22500--23100 cm-1 region. This study complemented the dispersed fluorescence work described above, so the author was asked to generate a model and interpret this spectra.;A Hamiltonian model to simulate rotational structure of asymmetric top molecules which includes spin-rotation terms has been written by the author to form part of a spectral simulation program. This program was used to simulate the rotationally resolved LIF spectra of ZnC2H5 detailed above. Unfortunately a complete analysis has not been possible but values for the A, B and C rotational constants for many of the bands are presented here along with a analysis of the observed values of spin-rotation constants.;Finally, LIF spectra of a new electronic transition of BaOH, the D˜2sum+ - X 2sum+ system has been observed. Also, the C˜ - X˜ system was reinvestigated. The C˜ - X˜ system is particularly interesting because it shows much more complexity than might be expected from previous studies. Vibrationally and partially rotationally resolved spectra are reported for both systems and the C˜ - X˜ region offers some evidence that the molecule may be bent in the excited state with a large spin-rotation interaction coupling.