18 December 1992 Optical emissions from oxygen atom reactions with adsorbates
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Although most optical materials are inert to the ambient low earth orbit environment, high velocity oxygen atoms will react with adsorbates to produce optical emissions from the ultraviolet into the infrared. The adsorbates arise from chemical releases or outgassing from the spacecraft itself. We have been investigating kinetic and spectral aspects of these phenomenon by direct observation of the 0.2 to 13 micrometers chemiluminescence from the interaction of a fast atomic oxygen beam with a continuously dosed surface. The dosing gases include fuels, combustion products and outgassed species such as unsymmetrical dimethylhydrazine (UDMH), NO, H2O and CO. The surface studied include gold and magnesium fluoride. In order to relate the results to actual spacecraft conditions these phenomena have been explored as a function of O atom velocity, dosant flux and substrate temperature. UDMH dosed surfaces exhibit spectra typical (wavelength and intensity) of carbonaceous surfaces. The primary emitters are CO, CO2, and OH. H2O dosed surfaces are dominated by OH and /or H2O emission while CO dosed surfaces are dominated by CO and CO2 emissions. The nitric oxide dosed surface produces a glow from 0.4 to 5.4 micrometers due to NO2* continuum emission. The emission was observed to increase by a factor of two upon cooling the surface from 20 degree(s)C to -35 degree(s)C.
© (1992) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
David B. Oakes, Mark E. Fraser, Mitzi Gauthier-Beals, Karl W. Holtzclaw, Mark Malonson, and Alan H. Gelb "Optical emissions from oxygen atom reactions with adsorbates", Proc. SPIE 1754, Optical System Contamination: Effects, Measurement, Control III, (18 December 1992); doi: 10.1117/12.140726; https://doi.org/10.1117/12.140726

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