Knowledge Bank

The assignments of the emission spectra of $Ca2$ in the red and in the green has been the subject of discussion recently at this Symposium (1) and in the literature (2,3). A definitive set of assignments has not yet been agreed upon. We have calculated the potential energy curves and transition moments of the ground $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g+$ and $1,2\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma 1u$ states of $Ca2$ using a first order CI approach. These calculations support the assignment of the observed red and green emission spectra of $Ca2$ to transitions between the ground state and the $1,2\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma +u$ states, respectively. Prediassociation of the $1\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma +u$ state by the $1\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\pi u$ state is shown the be possible.