Excitation of the 3p3PIsub(u) level of H2 by electron impact

The excitation cross-section of the 3p 3PIsub(u) level of H2 has been measured for electrons from energy threshold to 100 eV. The intensities of the emitted lines are compared to the Balmer lines whose excitation cross-sections from H2 are known. The effects of dissociation, cascade, polarisation and pressure are discussed. The maximum excitation cross-section is found to be 3.30 x 10-18 cm2 +- 50% at 22.5 eV. (author)