Fluorescence of cometary OH and CN

Thesis/Dissertation · Sat Jan 01 04:00:00 EST 1983

OSTI ID:5774734

Schleicher, D G

Calculations were performed of the fluorescent equilibrium of the molecules OH and Cn in the solar radiation field as a function of heliocentric radial velocity. For OH, comparisons of detailed, ultraviolet band profiles were made with the observed, high-resolution spectra of five comets. While a pure fluorescent equilibrium calculation is sufficient to reproduce the major variations seen in the band structure from one comet to another, some collisional quenching is required to match the detailed features. The fluorescence efficiency for the 0-0 band (A /sup 2/..sigma../sup +/-X/sup 2/..pi..) varies by a factor of 6 for radial velocities between -60 and +60 km s/sup -1/ at a heliocentric distance of 1.0 AU; the variation is less extreme for a distance of 0.25 AU. Relative intensities of the 1-0 and 1-1 bands also vary with velocity. The relative opulation inversion of the upper and lower levels of the X/sup 2/..pi../sub (3/2)/ ground state is also calculated for this same set of distances and velocities, with the results being consistent with 18 cm radio observations. For certain velocities, the inversion is found to vary significantly with heliocentric distance. Predictions of the infrared OH vibrational bands are made; the 1-0 band should be observable if a sufficiently high spectral resolution is employed. The rate of photodissociation of OH was also calculated as a function of heliocentric velocity, yielding a lifetime for OH (at 1 AU) ranging from 1.8 x 10/sup 5/ to 4.0 x 10/sup 5/s. For the same range of velocities, and using a new solar spectrum, the author recalculated the detailed structure of the CN violet 0-0 band.

• OSTI ID: 5774734
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500 -- Photochemistry
640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
FLUORESCENCE
HYDROXYL RADICALS
LUMINESCENCE
NITRILES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RADIATIONS
RADICALS
SOLAR RADIATION
STELLAR RADIATION