Collisional broadening of the Na D lines by xenon in high-pressure sodium arcs

Abstract

The shape of the Na D emission line wings is measured in a high-pressure sodium lamp with xenon buffer gas operated at two low values of the arc power. Under these conditions the collisional broadening of the quasi-static far wings by xenon is dominant. The author has calculated the shape of the far wings with several available sets of Na-Xe X 2 Sigma 1/2, A 2 Pi 1/2,3/2 and B 2 Sigma 1/2 interaction potentials using the classical quasi-static line-broadening theory. None of these sets gives completely satisfactory agreement with the measured Na D wings. The author proposes modifications to the available potentials and obtains good agreement with the measured blue and red Na D line wings (550-750 nm) and with the measured positions of the satellites at 560.2 and 590.9 nm. The proposed Na-Xe interaction potentials are valid for Na-Xe internuclear distances between about 0.3 and 0.9 nm.