STUDY OF VIBRATIONAL AND ROTATIONAL STATES OF ALKALI DIMERS IN A NOZZLE BEAM

Abstract

The internal states of $Na_{2}$ dimers in a supersonic nozzle beam have been characterized using white light and laser-induced fluorescence as a probe. With white light excitation the vibrational bands in the $Na_{2} B^{i} {\Pi}_{u} -X^{1}\Sigma_{g}^{+}$ flourescence spectrum are well resolved. The analysis of the band intensities gives the vibrational distribution of $Na_{2}$ molecules in the nozzle beam. This corresponds to a Boltzman distribution corresponding to a vibrational temperature of $153 \pm 5^{0} $K. The measurement of vibrational-rotational line intensities in the laser-induced fluorescence gives a rotational temperature of about $55^{0} $K. So far, no evidence for the presence of highly vibrationally excited dimers, as suggested by Gordon et al.