DISSOCIATION ENERGY OF CALCIUM MOLECULES

Abstract

The ground state dissociation energy of $Ca_{2}$ is determined using laser photoluminescence. Laser excited A $^{1}\Sigma_{u}^{+}$ state levels radiate to the X $^{1}\Sigma_{g}^{+}$ state resulting in observed vibrational progressions from $v^{\prime} = 0$ to the dissociation limit (for example, $v^{\prime} = 32$ at $J = 284, which are smoothly joined to an oscillatory continuum. The discrete-continuum junction, providing an accurate measure of the dissociation energy, has been measured for several J values between 28 and 160. Extrapolation to $J = 0$ yields the true dissociation energy of $1065.9 \pm 2 cm^{-1}$. High resolution data has been fit to Dunham coefficients emcompassing every bound level of the ground state. RKR potential curves have been calculated which extend to internuclear separations greater than 1.0 nm. Relative Franck-Condon factors for discrete transitions have been calculated and agree closely with measured intensities.