Rate constants for the reaction of CO2+ with O, O2 and NO; N2+ with O and NO; and O2+ with NO
TL;DR: In this article, the authors measured the reaction of CO2+ with atomic oxygen in a flowing afterglow system at 295°K at a rate constant 2.6 × 10−10cm3/sec and appeared to produce both O2+and O+ as product ions, approximately in the ratio 5:3.
About: This article is published in Planetary and Space Science.The article was published on 1970-08-01. It has received 160 citations till now. The article focuses on the topics: Reaction rate constant.
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TL;DR: In this paper, the first in situ measurements of the ionosphere of another planet were obtained by retarding potential analyzers of the Viking landers, and the results were presented with attention to: (1) the determination of the peak ion concentration at several altitudes, (2) the measurement of ion temperatures, and (3) an equatorward horizontal ion velocity observed at various heights.
Abstract: The first in situ measurements of the ionosphere of another planet were obtained by retarding potential analyzers of the Viking landers. These results are presented with attention to: (1) the determination of the peak ion concentration in the ionosphere layer at several altitudes, (2) the measurement of ion temperatures, and (3) an equatorward horizontal ion velocity observed at various heights. Both landers entered the ionosphere layer at solar zenith angles near 44 deg, and more structure was observed in the height profiles of ionospheric quantities on Viking 2, although the profiles were similar in shape to those of Viking 1.
488 citations
TL;DR: In this article, a model based upon Viking data is constructed of the Martian atmosphere, and a comprehensive quantitative discussion is given of the measurements of the ultraviolet dayglow, and detailed assessment is made of the heating of the neutral and ionized components of the atmosphere arising from the absorption of ultraviolet solar radiation.
Abstract: A model based upon Viking data is constructed of the Martian atmosphere, and a comprehensive quantitative discussion is given of the measurements of the ultraviolet dayglow. A detailed assessment is made of the heating of the neutral and ionized components of the atmosphere arising from the absorption of ultraviolet solar radiation.
297 citations
TL;DR: In this article, the effects of spin changes on the efficiencies and product distributions of gas-phase ion-molecule reactions are analyzed, and the examples discussed include metal- as well as non-metal containing systems, with some emphasis on various types of bond activation by "naked" transition-metal cations and structurally simple cationic transition metal oxides.
287 citations
TL;DR: Viking measurements of the Martian upper atmosphere indicate thermospheric temperatures below 200°K, temperatures much colder than those implied by remote sensing experiments on Mariner 6, 7, and 9 and Mars 3 as mentioned in this paper.
Abstract: Viking measurements of the Martian upper atmosphere indicate thermospheric temperatures below 200°K, temperatures much colder than those implied by remote sensing experiments on Mariner 6, 7, and 9 and Mars 3. The variability in thermospheric temperature may reflect an important dynamical coupling of upper and lower regions of the Martian atmosphere. Absorption of extreme ultraviolet solar radiation can account for observed features of the ionosphere and provides an important source of fast N and O atoms which may escape the planet's gravitational field. Isotopic measurements of oxygen and nitrogen impose useful constraints on models for planetary evolution. It appears that the abundance of N_2 in Mars' past atmosphere may have exceeded the abundance of CO_2 in the present atmosphere and that the planet also has copious sources of H_2O. The planet acquired its nitrogen atmosphere early in its history. The degassing rate for nitrogen in the present epoch must be less than the time-averaged degassing rate by at least a factor of 20.
263 citations
TL;DR: The relative outgassing rates of H2O and CO2 on Mars are comparable with terrestrial values, although absolute rates for Mars are lower by a factor of 103.
Abstract: Photochemical reactions in the martian exosphere produce fast atoms of oxygen, carbon, and nitrogen and provide large escape fluxes of these elements. They appear to play a crucial role in the evolution of the martian atmosphere. The relative outgassing rates of H2O and CO2 on Mars are comparable with terrestrial values, although absolute rates for Mars are lower by a factor of 103. Nitrogen is a trace constituent, less than 1 percent, of the present martian atmosphere.
256 citations
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TL;DR: This chapter describes the experimental and analytical techniques that have been developed for flowing afterglow applications to the quantitative study of ion–neutral reaction processes, and the dc discharge was found to be advantageous.
Abstract: Publisher Summary This chapter describes the experimental and analytical techniques that have been developed for flowing afterglow applications to the quantitative study of ion–neutral reaction processes. Most other techniques for the measurement of ion–molecule reaction rate constants are inherently unsuited for the examination of an ion reacting with a neutral where the neutral has the lower ionization potential, and sufficient data for this generalization did not exist prior to the flowing afterglow results. Charge transfer reactions of negative ions have sometimes been useful in establishing relative electron affinities of molecules, which are often difficult to measure. Positive ion charge-transfer reactions have, on occasion, been useful in establishing relative ionization potentials of molecules, generally known or better measured in more direct ways. The dc discharge had other advantages over the microwave discharge as well. Its geometrical configuration was more compatible with the detailed flow analysis, and it was more easily incorporated in metal flow tubes, which were soon found to be advantageous.
408 citations
TL;DR: In this article, a pulsed, flowing afterglow has been used to measure rate constants at room temperature for the following reactions involving NO: N2++NO→NO++N2,k1≈5(+1,−3)×10−10cm3/sec,N++O2↗NO++O↘N+O2+,k5≈1(+0.1, −0.2,−0.6)× 10−9cm3 /sec.
Abstract: A pulsed, flowing afterglow has been utilized to measure rate constants at room temperature for the following reactions involving NO: N2++NO→NO++N2,k1≈5(+1,−3)×10−10cm3/sec,N++NO→NO++N,k2=8(+1,−4)×10−10cm3/sec,O2++NO→NO++O2,k3≈8(+2,−5)×10−10cm3/sec,O++NO→NO++O,k4≤2.4×10−11cm3/sec. In addition the following related reactions have been measured: N++O2↗NO++O↘N+O2+,k5≈1(+0.1,−0.6)×10−9cm3/sec,N2++O2→O2++N2,k6≈1(+0.2,−0.6)×10−10cm3/sec,O2++N→NO++O,k7≈1.8(+0.2,−0.9)×10−10cm3/sec. Some additional information concerning the end products of N++O2 is offered.
139 citations
TL;DR: In this article, the rate constant for the reaction O(4S)+CO2(1Σ)→O(2Π)+CO(1 Σ)+15eV was measured to be 12±04×10−9cm3/sec in a pulsed flowing afterglow system.
Abstract: The rate constant for the reaction O+(4S)+CO2(1Σ)→O2+(2Π)+CO(1Σ)+15eV is measured to be 12±04×10−9cm3/sec in a pulsed flowing afterglow system This reaction violates the Wigner spin‐conservation rule and is probably the fastest such reaction to have been observed
90 citations
TL;DR: The importance of ion-neutral reactions in controlling the abundance of ions in the earth's ionosphere has been widely discussed in a number of theoretical papers [Bates, 1955; Bates and Nicolet, 1961; Norton et al., 1963; Nicolet and Sunder, 1963; Dalgarno, 1964; Ferguson et al..
Abstract: Following the initial suggestion by Bates and Massey [1947], the significance of ion-neutral reactions in controlling the abundance of ions in the earth's ionosphere has been widely discussed in a number of theoretical papers [Bates, 1955; Bates and Nicolet, 1961; Norton et al, 1963; Nicolet and Sunder, 1963; Dalgarno, 1964; Ferguson et al., 1965a, Donahue, 1966]. Further indications for the predominant effects of ionic reactions have been provided by actual measurements of ion density profiles with rocket-borne mass spectrometers [Johnson, 1961; Taylor and Brinton, 1961; Holmes et al., 1965]. However, until recently, the relative importance of many reactions in the ionosphere could not be assessed because a detailed knowledge of the individual thermal rate coefficients was either lacking or rather uncertain as a review of Paulson [1964] demonstrated. Since then, efforts in several laboratories have resulted in the experimental determination of many of the required rate constant values.
41 citations
TL;DR: In this article, the ion chemistry is discussed and model ionospheres are constructed and compared with the Mariner IV electron concentration, and two interpretations seem possible: (1) the ions are mostly atomic (probably O+) and the peak electron concentration occurs at a neutral concentration of about 109 cm−3, and (2) the ion are mostly molecular (possibly with O2+ dominant) and the ion concentration occurs in a neutral atmosphere with a rate coefficient of about 5 × 1010 cm −3.
31 citations