Research Staff: Lawrence P. Giver

Line positions and intensities for several hundred bands of CO₂ are tabulated in the HITRAN compilation of spectra of atmospheric interest. The intensities of most of the weak bands in this compilation have not been measured; the intensities have instead been determined from "Direct Numerical Diagonalization" (DND) as described in the literature. Many of these bands are significant absorbers in Venus' hot, dense atmosphere, since it is composed predominantly of CO₂. Some weak bands are prominent absorbers in the Venus near-infrared emission windows. Giver and Chackerian made laboratory measurements of the band at 4416 cm^-1 band, which is prominent in the 4040 to 4550 cm^-1 emission window, and therefore the correct intensity was important in the modeling work of others.

We have finished our measurements of the 01121-00001 perpendicular band at 5315 cm^-1 and 3 of its hot bands. The DND intensity computations for the combination perpendicular bands have not been regarded as reliable, so measurements of several of these bands can be used to improve the computations of the many other bands that cannot be measured. Indeed, our measured intensity for the 5315 cm^-1 band is about double the DND computed intensity adopted for the 1992 HITRAN computation.

Collaborators: Linda R. Brown, JPL; Charles Chackerian, Jr., SETI; Richard S. Freedman, SPRI

Point of Contact: Lawrence P. Giver, 650/604-5231, lgiver@mail.arc.nasa.gov