Pressure broadening of the sodium $3s$-$3p$ resonance lines by helium atoms.

Quantum mechanical calculations are performed of the emission and absorption profiles of the sodium $3s$-$3p$ resonance lines under the influence of a helium perturbing gas. We use carefully constructed potential energy surfaces and transition dipole moments to compute the emission and absorption coefficients at temperatures $T=158$, $240$, $403$, $500$, $1000$, $2000$ and $3000$~K at wavelengths between $500$ nm and $760$ nm. Contributions from quasi-bound states are included. The resulting red and blue wing profiles are compared with previous theoretical calculations and experimental measurements. Supported in part by NSF and NASA.