Wavelength dependent photofragmentation of organometallic molecules in a molecular beam

The photo fragmentation of organometallic molecules has been studied but these studies have been mainly conducted in narrow regions in the visible region or at certain laser lines in the ultraviolet. These studies have shown that organometallic molecules generally undergo an explosive mechanism in which the ligands are lost simultaneously. The studies described here suggest that this may not be the case for all organometallic molecules and that some unusual photo fragmentation processes occur.;Mass spectroscopic studies in the visible region between 410--690 nm in the gas phase using a pulsed molecular beam have been obtained. The wavelength dependences were further examined by obtaining REMPI spectra of selected ions. Luminescence experiments and laser-assisted chemical deposition experiments were also performed in an attempt to correlate the gas phase photo fragmentation to thin film formation.;Pd(hfac)2 was found to have a very sensitive wavelength dependence with regards to the formation of Pd+ and PdC+. Although both ions are observed at some wavelengths, tuning the wavelength by less than one nanometer results in the signal due to PdC+ disappearing below the limits of detection. This wavelength was further examined by recording REMPI spectra of both Pd+ and PdC+. A variety of other hfac ligand containing molecules were also studied.;A completely different type of wavelength dependence was observed in the case of chromocene. At some wavelengths of excitation, the intensity of the molecular ion was found to be larger than that of the bare metal ion. This unusual wavelength dependent fragment was correlated to the initially accessed excited states of the chromocene molecule.;(eta4-cycloocta-1,5-diene)(eta5-cyclopentadienyl)cobalt was studied to study the different fragmentation pathways that may be present in a molecule with two different ligands. The most interesting observation is that the two different ligands could be lost individually with the loss of a particular ligand being preferred at different regions of excitation. In addition, the coordinated ligand was found to undergo extensive fragmentation.;The gas phase photofragmentation of Cu[OCHMeCH2NMe2] 2 was also studied. Copper production was observed in both our mass spectroscopic and luminescence experiments but the resulting films were found to be highly contaminated with carbon and oxygen.