title: Collisions between metastable hydrogen atoms at thermal energies
abstract: The complex interaction potentials arising in the approach of two metastable hydrogen 2s atoms are calculated and the cross sections for ionization, excitation transfer, and elastic scattering are predicted. The measured cross section for associative ionization at E = 4.1 meV equals 2x10(-15) cm (2). We calculate a total ionization cross section of 2x10(-13) cm (2), varying as E(-2/3) at higher energies. Thus it appears that dissociative ionization is the major ionization channel. We find also that double excitation transfer into two excited H(2p) atoms is still more probable with the large cross section of 9x10(-12) cm (2) at E = 4.1 meV varying as E(-1/2) at higher energies. The detection of the resulting Lyman alpha photons would provide a diagnostic test of our predictions.
authors.affiliation: Penn State University, Berks-Lehigh Valley College, Reading, Pennsylvania 19610-6009 and Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA.
authors.initials: RC
authors.lastname: Forrey
authors.initials: R
authors.lastname: Cote
authors.initials: A
authors.lastname: Dalgarno
authors.initials: S
authors.lastname: Jonsell
authors.initials: A
authors.lastname: Saenz
authors.initials: P
authors.lastname: Froelich