Molecular Constants for the Ground Electronic State of Hydrogen

The resolution and accuracy of ground-based and space-craft spectroscopy of solar system bodies has improved dramatically over the last decade. This has driven the demand for high resolution and high accuracy laboratory spectroscopic measurements of molecules having significance for planetary atmospheres. Given the importance of H₂ for planetary atmospheres, the results from the most recent and most accurate measurements(1-6) have been compiled for easy reference. These include measurements of the line positions, line strengths, shifts in line position due to density, and self broadening parameters for the ground electronic state of molecular hydrogen. This paper also presents an improved set of vibration-rotation constants for the ground electronic state. A non-linear least squares procedure was used to fit all of the laboratory measurements for the approximately 35 observed transitions in the 0-0 through the 5-0 bands. Terms to the fifth order in the vibrational quantum number v and to the fourth order in J(J+1) produced a fit with an rms standard deviation of 0.006 cm(-1) . This work has been supported in part by NASA Grant NAGW 1765 and by Denison University. References: (1) Bragg, S. L. 1981, PhD Dissertation, Washington University. (2) Bragg, S. L., Brault, J. W., and Smith, W. H. 1982, ApJ, 263, 999. (3) Ferguson, D. W., Rao, K. N., Mickelson, M. E., and Larson, L. E. 1993, J. Mol. Spectrosc., 160, 315. (4) Jennings, D. W., Rahn, L. A., and Owyoung, A. 1985, ApJ Let, 291, L15. (5) Jennings, D. E., Weber, A., and Brault, J. W. 1987, J. Mol. Spectrosc., 126, 19. (6) Rao, K. N., Mickelson, M.E., and Trauger, J. T. 1990, J. Mol. Struct., 217, 85.