Broadening of theDLines and the Relaxation of the Resonance Levels of Sodium Due to Collisions with Helium

Abstract

Calculated potentials for the NaHe molecule are used to obtain collision-induced widths and shifts for the sodium D lines together with cross sections for fine-structure transitions and the relaxation of the multipole polarizations of the resonance levels. The atomic collision is treated in an adiabatic approximation in which the colliding atoms form a molecular system which rotates during the collision. We find the resonance lines to be broadened equally and to be approximately 70% wider, and with associated shifts of an order of magnitude smaller, than expected on the basis of van der Waals forces. The dependence of the cross sections for relaxation of the multipole polarizations of the resonance levels on the molecular-coupling conditions and the rotation of the system during collision is discussed and indicates a limitation on the sum rule for these cross sections. Good over-all agreement with the existing experimental data is obtained.

Collisional depolarization of light alkali atoms excited to their lowest 2P levels

“…[4], is not a consequence of the expansion, eq. [3], but an essential postulate which is suggested by the considerations following eq. [2].…”

“…[I]- [3], we expand the orbital states given in eq. [3] into states which are referred to the internuclear axis v rather than to the space-fixed quantization axis (the P axis).…”

Formation of an alignment in collisions of laser excited sodium with xenon atoms

“…If we choose for the moment the vector k-k' as the z-axis of our system then the T-operator (first term only) assumes the form =e2 ~eo (2' 9 cg(o=0, ~o)=c2~e(o2). (3) Consider that the laser beam populates the sublevels mj= + 1/2 and mj=-1/2 of 3p2P1/2 through pure a-excitation, incoherently at equal rates. From these levels through the T-operator Eq.…”

“…A considerable number of articles [3][4][5][6] was devoted to the purpose of calculating the transition probabilities among the entire set of Zeeman substates of sodium 3p doublet. The aim to deduce a comprehensive transition operator which accounts for all of these,…”

Analysis of Broadening and Shift of the 326.1 nm Cd Line by He and Ne

“…For such small R values {1 -SiiSff-1}Αng.Αv., occurring in formula (2) oscillates so rapidly (see Fig. 2 and [3,5,8]) that in calculations of this integral it may be replaced by its mean value [38]. Therefore we may assume that for the Cd-Rg (Rg = He, Ne) systems we have the Hund case "c".…”