Atomic oxygen-metal surface studies as applied to mass spectrometer measurements of upper planetary atmospheres

Sjolander, Gary W.

doi:10.1029/ja081i022p03767

Cited by 21 publications

(8 citation statements)

References 11 publications

(9 reference statements)

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“…Earlier estimates of the rate coefficients have shown that the effect of wall recombination of O atoms must be taken into account; we found that this effect is large when the wall is clean but slowly decreases to become negligible after O atoms have been flowing for an extended time. This observation is consistent with previous studies of different metallic surfaces, in which Sjolander found that the initial probability of O atom loss on clean surfaces was close to unity, while after a few hours, the probability of loss decreased to an acceptable level. We found a similar effect in our study of the reaction between C 10 H 8 + and O atoms; the apparent rate coefficient was first found to be ∼75% lower than the value reported in this paper.…”

Section: Methodssupporting

confidence: 93%

Reactions of Cations Derived from Naphthalene with Molecules and Atoms of Interstellar Interest

et al. 1999

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The chemistry of naphthalene radical cation and its derivatives (C10Hn +, n = 6,7,8,9) has been studied with molecules and atoms of interstellar interest in a selected ion flow tube. The radical cation C10H8 + is unreactive with H2, CO, H2O, and NH3 but reacts with H, O, and N atoms. Adduct formation is the only channel detected in the case of reaction with H atoms, but additional channels contribute in reactions between C10H8 + and O and N atoms; these latter reactions proceed through novel reaction pathways via C and CH abstraction, leading to the formation of the stable compounds CO and HCN, respectively. The closed-shell naphthylium cation C10H7 + is essentially unreactive with atoms but associates via nucleophilic addition with most of the molecules studied. The reaction kinetics are close to saturation in the accessible helium pressure range. The naphthyne radical cation C10H6 + does not react with H2, CO, or H2O but forms an adduct with NH3 at a moderate rate. Reactions with atoms were found to be very similar to those of C10H8 +. The implications of these results for the stability of polycyclic aromatic hydrocarbon cations in the interstellar medium are briefly discussed.

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Section: Methodssupporting

confidence: 93%

Reactions of Cations Derived from Naphthalene with Molecules and Atoms of Interstellar Interest

et al. 1999

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“…In some cases, particularly with high ambient densities associated with operation at low altitudes, it is necessary to differentially pump the device with consequent increases in instrument mass, power consumption, and overall complexity. Although careful attempts to quantify these features and calibrate instruments are usually made before flight, e.g., as in Cross, 39 both flight 35 and ground-based 40 tests indicate that achieving an accuracy of better than Ϯ50% for AO number densities is difficult.…”

Section: A Mass Spectrometersmentioning

confidence: 99%

“…The mass analyzer is unable to distinguish doubly ionized molecular oxygen (O 2 2ϩ ) from singly ionized AO ͑O ϩ ͒, because the mass/charge ratio is the same, while doubly ionized AO (O 2ϩ ) will be rejected altogether. Other complicating factors include the thermalization and/or recombination of incoming atoms in the ionizer stage, 35 and reactions of AO with contaminants both inside and outside the instrument. 36,37 It is reported in the literature that problems associated with recombination of AO within the device can be limited by the use of titanium for all internal surfaces of the spectrometer.…”

Section: A Mass Spectrometersmentioning

confidence: 99%

Satellite and rocket-borne atomic oxygen sensor techniques

Osborne¹,

Harris

Roberts

et al. 2001

Review of Scientific Instruments

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Neutral atomic oxygen (AO)—the dominant atmospheric species at typical low Earth orbit altitudes—is responsible for the erosion, or other degradation, of many satellite materials. Therefore, AO has become an important consideration for spacecraft designers and manufacturers. The study of AO is also of interest to atmospheric physicists because it is involved in many of the chemical reactions occurring naturally in the mesosphere and lower thermosphere. Both these groups rely on atmospheric models for computer-based simulation and prediction of atomic oxygen concentrations. Such models require, or are enhanced by, empirical input data—that is, actual measurements of AO number densities. A review is presented of the different measurement techniques that, to date, have been used on satellites and sounding rockets to perform AO studies. Rather than reporting results from every sensor application, this article takes a more general view of the experimental methods, using example devices to highlight their advantages and disadvantages. New or promising equipment, or techniques that could be exploited for performing such measurements, are also described. We attempt some semiquantitative comparison of the techniques, although the most appropriate experimental method for any given flight opportunity depends heavily on the mission conditions and science goals. Our emphasis is on missions where the available mass and power are limited. In these situations the most suitable established device is probably that of the thin film actinometer. If more risk can be assumed then a more promising, but as yet unqualified, method is that of the fiber-optic reflectance sensor. However, since both these devices are nonreusable, it is shown that semiconducting sensors may be better for long duration, mass- and power-limited applications.

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“…In the past, mass spectrometric measurement of atomic oxygen, a major constituent of the thermosphere at all altitudes, has been complicated by the presence of surface adsorption and recombination. Recent laboratory experiments using atomic oxygen beams [Lake and Mauersberger, 1974;Sjolander, 1976] have augmented prior empirical studies based on satellite data by providing a more detailed understanding of atomic oxygen-metal surface reactions. It is now customary on satellite-borne mass spectrometers to use the signal of O•.…”

Section: Introductionmentioning

confidence: 99%

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

Engebretson¹,

Mauersberger²

1979

J. Geophys. Res

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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 .

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Atomic oxygen-metal surface studies as applied to mass spectrometer measurements of upper planetary atmospheres

Cited by 21 publications

References 11 publications

Reactions of Cations Derived from Naphthalene with Molecules and Atoms of Interstellar Interest

Reactions of Cations Derived from Naphthalene with Molecules and Atoms of Interstellar Interest

Satellite and rocket-borne atomic oxygen sensor techniques

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

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