The impact of gas‐surface reactions on mass spectrometric measurements of atomic nitrogen

Abstract

Recently, atomic nitrogen has been measured in the upper thermosphere with a mass spectrometer carried on the Atmosphere Explorer satellites. Only a small fraction of N atoms are directly measured by the mass spectrometer, however. The majority appear as NO, formed within the ion source. Occasionally a relatively large NO: signal has also been observed, showing a strong dependence on the ion source surface temperature. Comparison of a numerical simulation of the reactions leading to NO: with data obtained in circular orbits on AE-C provides insight into the pertinent chemical reactions. It demonstrates that the techniques used in open source neutral mass spectrometer operation--warmup and outgassing of the source before measurements--were successful in minimizing the effects of this contaminant. ß '/' *e% * * * ß •oo ø d' • ß ß o ø ß ß ß ßß ß ß ß .

Radiative contamination in rocket‐borne infrared photometric measurements

“…In these cases, a process involving dissociation of N 2 molecules cannot be considered responsible. Engebretson and Mauersberger [1979] discussed implications of interactions between reactive gases and the surfaces of satellite-borne mass spectrometers, and they found good agreement between data and the model for NO2 signals, providing insight into the pertinent chemical reactions. Torr et al [1977] suggested that NO recombines with O on the walls of the instrument to produce emission in the NO2 continuum contaminating the satellite airglow measurements at low altitude.…”

“…has also been observed in measurements of neutral constituents in the upper atmosphere by using a mass spectrometer carried on the Atmosphere Explorer Satellites [Engebretson and Mauersberger, 1979]. The presence of contaminating emission in airglow photometers on the Atmosphere Explorer satellites has been reported both in the visible region [Tort et al, 1977] and in the ultraviolet region [Yee and Abreu, 1983].…”

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

“…Substantial indirect evidence exists, however, that this process can take place on many of the materials exposed to the airstream, including Orbiter's doped-silica glass tiles. (Analogous surface-catalyzed formation of O 2 *»t and N 2 *»t would also be expected, 10 as well as further products of reaction of the labile species present in the out-of-chemical equilibrium thermosphere, such as O 3 t and * Nitrogen and oxygen atoms have been found to have high probability of recombining on metallic interior surfaces of satellite mass spectrometers, 22 and indeed they usually convert to molecules in spaceborne pressure gages with glass or metal walls. 23 In the laboratory these two species recombine into a single electronically excited state at room temperature on several poly crystalline metals 7 ' 8 and glass.…”

Excitation of N2 Lyman‐Birge‐Hopfield Bands emission by low Earth orbiting spacecraft

“…Additionally, the temperatures of the previously sunlit recombination areas would tend to decrease somewhat by radiative cooling during the data period, which can either increase or decrease reaction rates at constant reactant densities. Production of the precursors of N2(B) and O2(A ) on laboratory polycrystalline metals generally increases with decreasing temperature in the 400K-300K range [Halstead et al, 1985]; and in space, the rate of reaction of O with NO to NO2* on shuttle's protective tiles and purposefully exposed engineering materials [Swenson et al, 1986], and to NO 2 on the •netal walls of mass spectrometers [Engebretson and Mauersberger, 1979], is also lar.•er at low surface temperatures. In contrast the probability of NO 2 formation on 300K-325K Cu at low fractional participant coverage has a small positive temperature dependence [Halstead et al, 1985]; and--perhaps most apposite to the S3-4 observations--the recombination probabilities of N atoms (to all states) on several metal surfaces at higher temperatures show complex behavior [Halpern and Rosner, 1978].…”