OBSERVATION AND ANALYSIS OF THE $2^{1}\Sigma^{+}_{g}$ STATE OF ${^{7}}Li_{2}$ and ${^{6}}Li_{2}$

Abstract

A transition in the $4700 - 7100 cm^{-1}$ region, from the previously unobserved $2^{1}\Sigma^{+}_{g}$ state of $Li_{2}$ to the $A^{1}\Sigma^{+}_{u}$ state has been observed in the Fourier Transform Infrared Spectrum of the Laser Induced Fluorescence excited by several lines of the argon ion laser. High resolution data have been obtained for seventeen vibrational levels of the $2^{1}\Sigma^{+}_{g}$ state of ${^{7}}Li_{2}$ and twelve levels of ${^{6}}Li_{2}$, thus establishing the vibrational numbering. Results of the rotational and vibrational analysis will be presented and discussed in relation to recent theoretical $predictions.^{1}$