Rubidium D1 and D2 atomic lines’ pressure broadened by ground-state helium atoms

Abstract

Full quantum calculations are performed to determine the spectral broadening of the rubidium D1 and D2 lines induced by collisions with helium perturbers. The potential curves of the low-lying RbHe molecular states, as well as the corresponding transition dipole moments, are generated theoretically with ab initio methods based on SA-CASSCF-MRCI calculations, including the spin–orbit effects. The absorption and emission coefficients at wavelengths lying between 650 and and temperatures ranging from 100 to 3000 K are determined. The absorption profile reveals it is dominated by the free–free transitions, whereas the emission spectral shape arises from the free–free and bound–free transitions. The resulting red- and blue-wing profiles are compared with previous experimental and theoretical works.