Measurement of the broadening and asymmetry of the calcium resonance line (422.7 nm)

Abstract

The broadening parameters of the calcium resonance line (422.7 nm) perturbed by rare gases have been obtained by laser fluorescence so as to be free of instrumental broadening. The data have been fitted directly to a more sophisticated lineshape which was found to describe the data to a much higher degree of accuracy than the usual Voigt profile. This modified lineshape (the asymmetric speed-dependent Voigt profile ASDVP) includes the effect of finite collision time and of correlations between pressure broadening and emitter speed. The values obtained for broadening by the rare gases He, Ne, Ar, Kr and Xe are as follows: 24.4, 14.9, 27.8, 28.9 and 33.7*10-24 mK m3 (full Lorentzian widths). The collision time asymmetry parameter, b, has also been measured for each of these gases, and the following values obtained: +1.04, +0.3, -0.7, -1.35 and -2.24*10-4 mK-1. A negative value indicates greater intensity in the red wing.