Knowledge Bank

The YH molecule has been generated in a molecular beam apparatus employing laser vaporization, and its visible spectrum has been re-investigated at low and high resolution. Several $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma -1\Sigma$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Pi -1\Sigma$ transitions, all with the same lower $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma$ state, have been observed in the 420-750 nim region. Many of the same bands were observed in the high tempereture emission experiment of Bernard and Bacis (Can. J. Phy.., 55, 1322 (1977)). They also observed strong transitions in the 550-560 me region, which they assigned as the (0.0) band of the $a3\Phi -X3△$ system. No triplet-type transitions have been observed in our low temperature experiment which suggests that the ground state of YH is a $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma$ state, in agreement with recent ab inittio calculations. Detailed analysis and comparisons will provided at the meeting.