HIGH RESOLUTION LASER EXCITATION SPECTROSCOPY OF SrCH$_{3}$, CaBH$_{4}$ AND SrBH$_{4}$
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Date
2006
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Publisher
Ohio State University
Abstract
High resolution laser excitation spectroscopy has been used to record the $\widetilde{A}\;^{2}\textrm{E} - \widetilde{X}\;^{2}\textrm{A}_{1}$ electronic transition of SrCH$_{3}$ in a laser ablation/molecular jet source. SrCH$_{3}$ was synthesized by the reaction of UV-ablated strontium atoms with a 1$\%$ mixture of tetramethyl tin in argon. Transitions arising from the K$^{\prime}$=1 $\gets$ K$^{\prime\prime}$=0, K$^{\prime}$=0 $\gets$ K$^{\prime\prime}$=1 and K$^{\prime}$=2 $\gets$ K$^{\prime\prime}$=1 sub-bands have been observed and assigned. Rotational and fine structure parameters have been determined for the $\widetilde{A}\;^{2}$E state. An analysis of the spin-orbit and spin-rotation constants indicates that the $\widetilde{A}\;^{2}$E state does not arise entirely from an atomic orbital of \textit{p} character. In addition, the Jahn-Teller coupling was found to be negligible in the zero-point vibrational level of the $\widetilde{A}\;^{2}$E state. The rotational constants were used to estimate a structure for SrCH$_{3}$ in the $\widetilde{A}\;^{2}$E state. The geometry changes observed between the $\widetilde{X}\;^{2}\textrm{A}_{1}$ and $\widetilde{A}\;^{2}$E states of SrCH$_{3}$ are similar to those observed for CaCH$_{3}$. In addition, the $\widetilde{B}\;^{2}\textrm{E} - \widetilde{X}\;^{2}\textrm{A}_{1}$ transitions of CaBH$_{4}$ and SrBH$_{4}$ have been observed. The metal borohydrides were synthesized in a jet source by reaction of UV-ablated metal atoms with a 5$\%$ mixture of diborane in argon. A rotational analysis is currently in progress and a comparison of the spectroscopic and structural parameters for both molecules will be presented.
Description
Author Institution: Department of Physics, University of Waterloo, 200 University Ave. West,; Waterloo, ON, N2L 3G1 Canada; Department of Chemistry, University of Waterloo, 200 University Ave. West,; Waterloo, ON, N2L 3G1 Canada