Laser spectroscopy of metal-containing molecules and Fourier transform spectroscopy of small molecules.

Abstract

Metal containing molecules were studied in the gas phase. These compounds were synthesized in a Broida-type oven by the high temperature reaction between metal atoms and appropriate oxidants. The laser-induced fluorescence technique was employed to detect the products from these reactions. These inorganic molecules, consisting of a metal atom bonded to a single ligand, are ionic and can be represented by the structure M⁺L⁻(M = Ca, Sr, Ba and Cu). The BaOH and BaOD molecules were studied at low resolution. The band origins were found and the vibrational assignments were carried out for the òΠ-X²Σ⁺ transition, which has been previously seen. The nominally forbidden Ã' ²Δ-X² Σ⁺ transition was observed for the first time for alkaline earth polyatomics. Three electronic transitions were detected for the metal monohydrosulphides and metal monothiolates. The spectra are consistent with a bent Ca-S-R structure. Some Ca-S and Sr-S stretching frequencies were determined from the spectra. The B¹A"-X¹A' transition of CuOD molecule was rotationally analyzed at high resolution using the filtered laser excitation technique. Rotational lines up to K', K" = 7 sub bands have been measured. Molecular constants were obtained for the ground and excited states by fitting these lines to a asymmetric rotor Hamiltonian. These constants will be helpful for assigning the red systems of CuOH and CuOD. The emission spectra of boron containing compounds, BC, BH and BD, were recorded using a high resolution Fourier transform spectrometer. These compounds were made in a B₄C/Cu composite-wall hollow cathode lamp. The B⁴Σ⁻-X⁴Σ⁻ transition of BC was observed near 17900 cm⁻¹. The ground state internuclear separation was found to be 1.488A. The rotational constants for different vibrational levels were obtained from fitting the rotational lines. The A¹Π-X¹Σ transition was analyzed for BH and BD in order to find accurate rotational line positions and precise molecular constants. The rotational lines of BH were fit to a Dunham-type expression and equilibrium molecular constants were obtained. The vibrational levels of the A¹Π state are very anharmonic. During the course of the study of BD, the A¹Σ⁺-X¹Σ⁺ transition of CuD was also observed. This spectrum contained rotational lines from both ⁶³CuD and ⁶⁵CuD isotopomers and improved molecular constants were obtained by the analysis of the data.