The broadening of d–f and f–d transitions by collisions with neutral hydrogen atoms

The theory of Anstee & O'Mara for the broadening of spectral lines owing to collisions by neutral hydrogen atoms is extended to d–f and f–d transitions of neutral atoms. Width cross-sections are tabulated against effective principal quantum numbers for the upper and lower states of the transition, for a relative collision velocity of 104 m s−1. The cross-sections are fitted to a variation with velocity of v−α, and results for the velocity parameter α are similarly tabulated. The data are tested by application to d–f spectral lines in the solar spectrum. The derived abundances are consistent with those for meteorites.