Knowledge Bank

Optical-optical double resonance experiments on CaF have been performed using two cw dye lasers. The $E\prime \mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Pi -A2\Pi$ and $A2\Pi -X2\Sigma +$ transitions are sequentially pumped by Rhodamine 110 and 6G dye lasers respectively. The $E\prime \mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Pi$ state ($T0\sim 34490cm-1,Bo\sim 0.358cm-1$) has not been observed previously and a vibration-rotation analysis is in progress. $E\prime \mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Pi -B2\Sigma +$ fluorescence allows analysis of the $B2\Sigma +$ state [preliminary constants $To=18830(2)cm-1,we=571.5(5),wex3=3.0(2),Bo=0.3439(5)cm-1$. The differences between these constants and those in $Rosen1$ are due to a large separation between bandheads and origins and to an error in the previous B-X rotational $analysis2$ In addition, the double resonance fluorescence spectrum contains a cascade $Z-A2\Pi$ transition. The Z state is either $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma$ or $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Delta$ and has $To\sim 30170cm-1,Bo=0.362cm-1$. Semi-empirical and SCF-CI calculations of the electronic structure of CaF will be discussed with particular emphasis on the location on the lowest energy $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Delta$ state.