Determination of low pressure broadening and shift rates for K, Rb, and Cs collisions with rare gases from Anderson Tallman theory

Abstract

A mathematical method is described to compute the pressure dependent spectrum of the D 1 and D 2 lines of atomic cesium in the presence of argon. The method is based on the Anderson Tallman unified theory of pressure broadening in which the spectrum is determined form the Fourier transform of the auto-correlation function. The method uses modified potential energy surfaces of the ground and excited states that correlate to the 2 S 1/2 ground state and the 2 P 1/2 and 2 P 3/2 excited states at large inter-nuclear separation. These surfaces are used to form interaction difference potentials to determine the auto-correlation function. In addition to being able to compute pressure dependent spectra that exhibit asymmetry and far wing structure the method also allows us to compute the low pressure shift and broadening rates of the Lorentzian line core.