Knowledge Bank

High resolution laser excitation spectroscopy has been used to record the $A~2E-X~2A1$ electronic transition of SrCH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ in a laser ablation/molecular jet source. SrCH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ was synthesized by the reaction of UV-ablated strontium atoms with a 1$\%$ mixture of tetramethyl tin in argon. Transitions arising from the K=1 $\leftarrow$ K=0, K=0 $\leftarrow$ K=1 and K=2 $\leftarrow$ K=1 sub-bands have been observed and assigned. Rotational and fine structure parameters have been determined for the $A~2$E state. An analysis of the spin-orbit and spin-rotation constants indicates that the $A~2$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 $A~2$E state. The rotational constants were used to estimate a structure for SrCH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ in the $A~2$E state. The geometry changes observed between the $X~2A1$ and $A~2$E states of SrCH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ are similar to those observed for CaCH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$. In addition, the $B~2E-X~2A1$ transitions of CaBH$\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}$ and SrBH$\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}$ 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.