Laser-induced charge-transfer collisions of calcium ions with strontium atoms

Experimental studies of two laser-induced charge-transfer reactions in Ca and Sr are presented. In both reactions, a Ca ion collides with an Sr neutral in the presence of a laser field to produce a Ca neutral and an excited Sr ion. The two reactions differ in the final level of the ${\mathrm{Sr}}^{+}$ species. The collision cross sections associated with these reactions are studied as functions of applied laser frequency and power density. The largest cross section induced is equal to ${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$, obtained at a power density of 2×${10}^9$ W/${\mathrm{cm}}^2$. Differences in experimental results associated with the two reactions are explained qualitatively by an examination of the potential curves of the Ca${\mathrm{Sr}}^{+}$ quasimolecule.