SPECTRAL-LINES AND DISTRIBUTION OF H-3(+) IN HIGH ROTATIONAL LEVELS

Infrared spectrum of the v(2) fundamental band of H-3(+) in high rotat ional levels has been studied. Three motives for this study were (i) t o provide laboratory data for the observation of astronomical objects in which a large abundance of H-3(+) exists at high temperature, (ii) to study kinetic energy distribution of H-3(+) in plasmas and to deter mine its rotational and translational temperatures, and (iii) to provi de information on high rovibrational states for the variational calcul ations on the intramolecular dynamic of H-3(+). In order to increase t he kinetic temperature, water-cooled plasmas with helium dominated gas mixtures with He/H-2 similar to 5/0.6 torr were used. The observed ro tational level in the ground state with the highest rotational quantum numbers was J = K = 15 which has the rotational energy of 5091.6 cm(- 1). It was found from the observed relative intensities of the rovibra tional transitions and linewidths that H-3(+) in the plasmas were in a pproximate thermal equilibrium with both rotational and translational temperature of similar to 1000 K. On the contrary, an analysis of the relative intensities of the H-3(+) spectral lines observed in our prev ious study of carbocation spectroscopy showed nonthermal rotational di stribution. A semiquantitative discussion is given on the observed res ults.