Abstract
Absolute cross sections for the electron capture process H++X to H(2s)+X+ have been determined for protons in He, Ne, N2 and O2 at 16 keV and for Ar and H2 within the range 12-28 keV. A nitric oxide filled photoionisation chamber has been used to record the Lyman alpha radiation emitted by electric field quenching of fast metastable H(2s) atoms formed in single collisions. Unlike previous measurements by Andreev (1966) full account has been taken of the polarisation of the quench radiation. The present results, which involve smaller uncertainties, are found to agree on average to within 4% of the cross sections at 16 keV reported by Andreev.