The broadening of strong lines of Ca+, Mg+ and Ba+ by collisions with neutral hydrogen atoms

The theory of Anstee &38; O'Mara is extended to the line broadening of transitions of singly ionized atoms by collisions with neutral hydrogen atoms. The theory is used to calculate broadening cross-sections for strong lines of singly ionized calcium, magnesium and barium. The broadening cross-sections calculated are compared with both theoretical and empirical results of other workers.