Collisional de-excitation of 5-26 keV metastable hydrogen atoms

A technique in which the H(2s) metastable population of a fast hydrogen atom beam is modulated by electric field quenching has been used to study the collisional de-excitation 5-26 keV H(2s) atoms in passage through H2, He, Ne, Ar and Kr. Cross sections σsub(2s,2p) for 2s-1s de-excitation via the 2p state have been determined for the first time and shown to account for no more than about 15% of the total cross section for de-excitation. Checks have also been made on previously measured total cross sections for collisional destruction and cross sections for one-electron loss by H(2s) atoms. (author)