15min:

MICHEL VERVLOET, Laboratoire de Photophysique Moléculaire du CNRS, Bâtiment 350, Université de Paris-Sud, 91405 Orsay Cedex, France; JAMES K. G. WATSON, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada, K1A OR6.

Electronic emission spectra of the neutral H₃ and D₃ molecules obtained with a Droege-Engelking corona discharge source were described at a previous symposium. The present work is concerned with analyses of these data for the complex of 3d, 3s, and 3p₀ upper states, where the symbols mean nl . The lower states are 3p₁ (for the infrared) and 2p₀ (for the visible). In H₃ a (3s, 3d₀) perturbation is recognised, in addition to the (3p₀, 3d₁) perturbation discussed previously. The decreased interference by H₂ or D₂ in these spectra has made it possible to improve the lower-state combination differences and constants. However, the standard deviations in the fits of the upper states of both H₃ and D₃ are still quite large. This is possibly due to numerous small perturbations by background states. It would also be desirable to replace the present effective Hamiltonians by a variational-type treatment of centrifugal effects.