Tensorial depolarization of alkali atoms by isotropic collisions with neutral hydrogen

TL;DR

This paper calculates tensorial collisional components for alkali atoms with neutral hydrogen, providing power-law formulas to facilitate modeling atomic polarization in solar observations.

Contribution

It introduces simple power-law expressions for tensorial collisional components of alkali atoms, enabling efficient depolarization rate calculations.

Findings

Tensorial components obey simple power laws.

Results enable better modeling of atomic polarization profiles.

Facilitates treatment of D1-D2 lines in alkali atoms.

Abstract

Results. We consider the problem of isotropic collisions between an alkali atom and neutral hydrogen. We calculate the collisional tensorial components of general p and s-states, characterized by their effective principal quantum number $n^{*}$. It is found that the behaviour of the tensorial components obey simple power laws allowing quick calculations of the depolarizing collisional rates. As application, our results should allow a rigorous treatment of the atomic polarization profiles of the D1 -D2 lines of alkali atoms. Conclusions. Close coupling treatments of atomic collisions are needed to decipher the information encoded in the polarized radiation from the Sun. Important problems remain unresolved like the role of collisions in the Paschen-Back conditions.