Premium
Infrared background of spacecraft in low‐Earth orbit attributable to ion chemistry
Author(s) -
Dressler Rainer A.,
Murad Edmond
Publication year - 1995
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/95gl03418
Subject(s) - infrared , excited state , infrared spectroscopy , spectral line , ion , luminescence , atomic physics , physics , materials science , chemistry , optics , astronomy , quantum mechanics
A diurnal variation in the infrared background radiation observed on Spacelab 2 suggests that ion chemistry plays a part in the generation of those infrared emissions. Because water is the major contaminant in the environment of spacecraft in low earth orbit, it is thought to be the source of vibrationally excited and infrared active H 2 O + formed in O + ( 4 S) + H 2 O charge‐transfer reactions. H 2 O + infrared luminescence spectra (0.01 µm FWHM) are calculated for the predicted nascent vibrational distribution as well as for steady‐state conditions assuming a charge‐transfer relative velocity of 7.8 km s −1 , the low‐Earth orbital velocity. The calculated luminescence spectra exhibit an intense band between 3 and 3.5 µm, attributable to symmetric stretch deexcitation, and a minor band between 6 and 8.5 µm associated with bending vibrational transitions. The effect of charge‐transfer product rotational temperature, H 2 O partial pressure, and motional electric field on the infrared background spectra are investigated.