Destruction of 0.1-3000-eV metastable hydrogen atoms in collisions with helium and argon

Total deactivation cross sections for collisions of metastable H (2 $sup 2$S) on He and Ar have been measured in the energy range 0.1--3000 eV. At low collision energies an apparatus designed to utilize time-of-flight techniques was used, while at the high energies an apparatus that employed beam-attenuation techniques was used. The cross sections are found to be on the order of 10$sup - 14$ cm$sup 2$ at the lowest energies and decrease slowly to approximately 10$sup - 15$ cm$sup 2$ at the highest energies. The experimental data were analyzed to obtain information about the difference in potential energies, $delta$V (R), between the two $sup 2$$Sigma$ molecular states arising from the H(n=2)+He and Ar separated atoms. Our analysis also shows that the dominant deactivation mechanism of H(2 $sup 2$S) at energies less than 500 eV is excitation to H(2 $sup 2$P), which rapidly radiates to the ground state.