Balmer alpha emission in collisions of fast H2molecules with N2, O2, H2O and CH4

Balmer alpha emission resulting from the passage of 10-100 keV H 2 molecules through N 2 , O 2 , H 2 O and CH 4 has been studied experimentally. For H 2 O and CH 4 Doppler-shifted and unshifted H alpha emissions were separately recorded. Cross sections have been determined for (i) the production of fast H(3s) atoms, (ii) total H alpha emission from the fast projectile and (iii) H alpha emission arising from dissociative excitation of H 2 O and CH 4 .