Kinetics of Nitrogen Atom Recombination

Herron, John T.; Franklin, J. L.; Bradt, Paul; Dibeler, Vernon H.

doi:10.1063/1.1730119

Cited by 80 publications

(32 citation statements)

References 12 publications

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“…The results of this work are consistent with [4,5] H+H,, the earlier observations of Johnson (7) and [6] H + H + H 2…”

Section: Resultssupporting

confidence: 92%

Hydrogen Atom Recombination on Glass Surfaces

Bader¹,

Gesser²

1972

Can. J. Chem.

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The adsorption and recombination of H atoms at temperatures between 77 and 110 "K have been studied on various silicate glass surfaces consisting of fused silica, porous Vycor with surface adsorbed water, and porous Vycor with chemically altered surfaces achieved by replacement of the surface functional hydroxyl group by chlorine, fluorine, and methoxy substituents.The concentration of adsorbed H atoms was determined by a measurement of the e.s.r. signal and the kinetics of the disappearance of the hydrogen atoms were observed to be second order in mobile atoms, consistent with a diffusion controlled recombination process.The results require that there be at least two types of surface adsorbed atoms, namely, weakly physically adsorbed atoms that are mobile and immobile. Identification of these adsorbed atom types with a particular surface functional feature leading to the adsorption is proposed.The activation energy for the second order decay of hydrogen atoms at the surface was found to vary from 1.0 to 2.3 kcal/mol, depending upon the chemical nature of the surface. A correlation between this activation energy and an electronegativity function of the surface group is presented.

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“…The results of this work are consistent with [4,5] H+H,, the earlier observations of Johnson (7) and [6] H + H + H 2…”

Section: Resultssupporting

confidence: 92%

Hydrogen Atom Recombination on Glass Surfaces

Bader¹,

Gesser²

1972

Can. J. Chem.

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“…The observation of Kauf~nan and I<elso (25) that, under corlditiorls similar t o those where essentially no a~ll~nollia destruction is observed (6,8), certain thermal effects appear to be caused by excited n~olecules would seem a t first sight contradictory to the present worlc. Note, however, that Dressler (26) has observed ground-state nitrogen in the first vibrational level as a compo~lent of active nitrogen.…”

Section: Efi~alje and -1rnrnoniasupporting

confidence: 44%

“…work. A multiorder origin for the second active species also serves to explain the observations that, when a microwave discharge is used so that the atoll1 concentration is very low even in the discharge tube, little or no ammonia destruction is found (6,8), and excited ~nolecules are not observed by mass spectro~netry (11,24).…”

Section: Efi~alje and -1rnrnoniamentioning

confidence: 92%

“…I t is seen in Table I that equation [8] is by itself sufficient to correlate the data. One thus co~~cludes that the ethylene reaction can be ac1equ'~tely esplailled in terms of a combination of reactioils [I] and [2] with [3] and/or [5], wliere pd -, 0, the last two processes being vdrieties of what iuay be called honzogeneozrs catalyzed recombination.…”

Section: Ethylenementioning

confidence: 99%

“…On the other hand, ordinary homogeiieous and surface decal-, as well as recombination catalj-zed by a Prodzict, mould necessarily be swamped in the presence of a large excess ol reactant, and \vould therefore have no effect whatsoever on a limiting reactivity.) By contrast, the destruction of ammonia by active nitrogen, while occurring to only a small extent, appears to be unaffected by moderate changes in temperature, is quite rapid (5), is accompanied by only partial quenching of the afterglo~v ((6, 7), ancl apparently does not iilvolve N atoms in the rate-controlling step (6,8). 3 The behavior of am~nonia is therefore, a t least s~iperficially, not consistent wit11 a combiilatioil of N atom attack plus catalyzed recoinbinatior~ and has, in fact, seeined to require an alternative explanation in which it is assuinecl that an active species other than the N atom is present in active nitrogen (see, for example, 5, 9, 10).…”

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confidence: 99%

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Catalyzed Recombination of Nitrogen Atoms, and the Possible Presence of a Second Active Speciesin Active Nitrogen

Kelly¹,

Winkler²

1960

Can. J. Chem.

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The reactions of ethylene, ethane, and ammonia with active nitrogen have been studied over the pressure range 0.3 to 4 mm zlsi7zg a n z~nlteated reaction vessel. The object was to determine why each reactant shows, as is well-lanown, a smaller extent of reaction a t lower temperatures than would be predicted from the atorn concentration. It was concluded that ethylene probably brought about ltomoge~zeot~s cczlalyred recoii~hinalion, i.e. the process N + C2H4 + N.C?H.,, followed by N + N.C?I-I< + N? + C?Hr. The over-all third-order rate constant appeared to be very large, about 1.8X10-28 cc2 1nolec~1le-~ seccl. The behavior of ammonia was quite different from that of ethylene and it was, in fact, possible to show that the extent of reaction was not governed by the instantaneous atom concentration a t all. The results can be explained qualitatively, however, if it is assumed that excited ll~olecules formed in the course of homogeneous atom decay constitute a second active species in active nitrogen. This view serves also t o explain the failure in such work as that of Kistialcowsky et al. to observe ammonia destruction or escited molecules when especially low atom concentrations are used. The few esperime~lts involving ethane were sufficient to show that the reactivity was low for a different reason than with ethylene.I11 a previous study ( I ) , active nitrogen was produced in a condensed discharge a t pressures between 0.3 and 4 IIIIII and under conditions of approximately complete initial dissociation. I t was then allowed to flo~v rapidly through a "decay tube" to a reaction vessel, where the limiting (i.e. maximum) rate of I-ICS production from ethylene or ethane a t 350' C was assumed to measure the flowrate of residual N atoms. Informntion on the rate constants for N atom decay was thus obtained. The present experiments have been co~lducted along similar lines, the same apparatus being used; however, the L L a~t i v i t y " of the active nitrogen has been derived with the reaction vessel z~nlzeated. 11Ieasurements were made of I-ICN production from ethylene and ethane, and also of the decomposition of ammonia.Ethylene and ethane are of particular interest a t lower temperatures since they are typical of several substances with which the extents of reaction a t all temperatures approach well-defined limiti~lg values as the flowrate of reactant is increased, yet these values are significantly temperature dependent and, except a t the highest temperatures, are substantially less than might be expected from the available N atom concentration (2, 3, 1). An explanation for such behavior has been given by Forst et al. (A), who suggested that N atoll1 reactions might be accompru~iecl by extensive recombination of the atonls catalyzed by the reactant. (Such a process is not eliniinatecl by increasing the flo\vrate of reactant provided it is of the same order in reactant as the main reaction. On the other hand, ordinary homogeiieous and surface decal-, as well as recombination catalj-zed by a Prodzict, mould ...

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