Infrared emission from NO2(asterisk) and NO(asterisk) desorbed from spacecraft surfaces

Abstract

Earth orbits. The principal discrete NO 2 features are the v 3 fundamental sequence near 6.2 am and v l + v 3 intercombination bands near 3.6 urn; in addition, the manifold of overlapping electronic transitions of this molecule extends to ~ 3 am. NO recombined from N and O would emit its familiar fundamental and first overtone bands above 5.3 and 2.7 am. The long radiative lifetimes of the upper vibrational states lead to infrared emission from volumes having dimensions comparable with or greater than those typical of spacecraft, with correspondingly reduced column-intensities in most view projections. From the spectroscopic properties of these molecules we estimate the numbers of photons that would be emitted in each infrared band sequence per recombination reaction and the resulting radiances relative to those of the observed visible glow from NO 2 * and anticipated ultraviolet glow from NO*.