Energy distribution among reaction products. Part 1.—The reaction atomic hydrogen plus molecular chlorine

Charters, P. E.; Polanyi, J. C.

doi:10.1039/df9623300107

Cited by 76 publications

(12 citation statements)

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“…The observed population, N v, is related to the specific chemical rate, k (v), into vibrational level v, by the following general stationary state equation. 50 [Normally all quantum numbers referring to product states are primed to distinguish them from reactant states. To avoid confusion the primes have been omitted in Eq.…”

Section: Discussionmentioning

confidence: 99%

Energy Distribution Among Reaction Products. IV. X+HY (X ≡ Cl, Br; Y ≡ Br, I), Cl+DI

Maylotte

Polanyi

Woodall

1972

The Journal of Chemical Physics

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190

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The distribution of vibrational, rotational, and translational energies (symbolized by V′, R′, and T′) have been obtained for the products of the isotopic pair of reactions Cl + HI → HCl + I and Cl + DI → DCl + I. The experimental method was the ``arrested relaxation'' variant of the infrared chemiluminescence technique. Detailed rate constants k(V′, R′, T′) are reported in the form of contour plots for these reactions. The total detailed rate constants into specified vibrational quantum states for Cl+HI (summed over the rotational levels of each v′ level) are k(v′ = 1) = 0.22, k(v′ = 2) = 0.35, [k(v′ = 3) = 1.00], k(v′ = 4) = 0.74; and for Cl + DI, k(v′ = 1) ≈ 0.08, k(v′ = 2) = 0.14, k(v′ = 3) = 0.35, k(v′ = 4) = 0.73, [k(v′ = 5) = 1.00], k(v′ = 6) = 0.05 [relative to the highest rate constant k(v̂′) = 1.00, in each case]. Preliminary energy distributions are also reported for the products of two other reactions, Cl + HBr → HCl + Br and Br + HI → HBr + I, in the X + HY → HX + Y family (X and Y are halogen atoms). The members of this family of reactions channel a substantial fraction of the energy available to the products into vibrational and rotational excitation, and only a small fraction into relative translation. For the Cl+HI and also the Cl+DI reaction the fractions are f̄V′ + f̄R′ (= 0.71 + 0.13) = 0.84; in contrast to f̄T′ = 0.16. As a corollary there is a marked inverse correlation between vibrational and rotational excitation in the reaction products. Despite the fact that the detailed rate constants into specified product quantum states [k(v′, J′)] are markedly different for the isotopic pair of reactions, the fractional conversion of the available energy into vibration, rotation, and translation are in close agreement (to ∼ ± 1%). This close parallelism in f̄V′, f̄R′, f̄T′ is in accord with predictions from classical trajectory studies. It indicates the usefulness of such calculations even for the case of reactions which yield products with widely spaced (vibrational and rotational) quantum levels.

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Section: Discussionmentioning

confidence: 99%

Energy Distribution Among Reaction Products. IV. X+HY (X ≡ Cl, Br; Y ≡ Br, I), Cl+DI

Maylotte

Polanyi

Woodall

1972

The Journal of Chemical Physics

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190

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“…The stationary-state distribution for the lowest H-atom concentration is very similar to that obtained in Charters and Polanyi's experiments (2). The factors governing relative vibrational stationarji-state concentrations in Charters and Polanyi's experiments were adjudged to be the rates of chemical reaction into each vibrational level, the rates of radiation into and out of each level, and the rate of removal from the vessel by pumping.…”

Section: Variation In H -A T O M Concentrationmentioning

confidence: 54%

“…Even normal thermal collisions, however, would have a high collision efficiency. In Section 1, it will be shown that the translational-rotational temperature of the bulk of the gas is 1250 f 50 OK. At this temperature reaction [2], which has a n activation energy of ca. 6 Itcal/mole, would occur every 10-100 collisions (assunling a steric factor of 1-0.1).…”

Section: Resultsmentioning

confidence: 99%

“…6 Itcal/mole, would occur every 10-100 collisions (assunling a steric factor of 1-0.1). Since the v = 1 level of HC1 is 8.23 kcal above v = 0, [2] will form HC1 prinlarily in v = 0.…”

Section: Resultsmentioning

confidence: 99%

“…The C1 that collides with H ? in reaction [2] c o~~l d therefore have excess energy (Hz is present in excess and is the most liltely gas-phase 'coolant'). Even normal thermal collisions, however, would have a high collision efficiency.…”

Section: Resultsmentioning

confidence: 99%

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The Hydrogen–chlorine System in the Mm Pressure Range: I. Energy Distribution Among Vibrationally Excited States

Findlay¹,

Polanyi²

1964

Can. J. Chem.

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\;\;hen atomic plus n~olecular hyc!rogen corning from a Wood's discharge 1-ube are nlixccl with niolecular chlorine, infrared emission is observed (1). At low reagent pressures, -10-2 lnln Hg, this emission can be related to the relative rate of the react-ion H + Cls + HClt, f C1 proceeding to form HC1 in vibrationally escitetl states v = 1-6, of the grou~ld electronic state. In the present work this system has been investigatecl for the first time a t -100X. the reagent pressure (-1 111111 IIg). The reaction was shown to proceed by a chain mechan~sm. The translatio~ial-rotational temperature was 1300 f 100 "I< under the experirne~ltal conditions nor~nally used. T h e vibrational distribution was notable for the presence of vibrators in levels v = 7 and S, which are respectively 4 and 10 kcal higher in energy than the exothermicity of the H + C12 reaction. The population in these levels appeared to be related to that in the levels with v < 6; it was proposed that vibrational-vibrational eschange among these lower levels was responsible for populating the higher ones. A simple nod el yieldecl a collisio~l efficiency for HClt,=, f HClt,,o -+ HClt,,7 + HCll,-0, of .Z1,~l = 6 X lo3 collisions per transfer. Addition of HCI to the reaction mixture brought about a redistribution among vibrationally excited states indicative of a fast vibrational transfer, HCl,,o + HCIt,-? + 2 HClt,-l.At reduced pressure of HCIt the stationary-state distribution among higher vibrational states approximated closely to that observed a t lo-? mm Hg total pressure (where collisional deactivation is insignificant), suggesting that collisional deactivation was not of major importance even a t the pressure used in the present work. In order t o account for the high translational-rotational temperature, in the absence of substantial vibrational deactivation, it was necessary to suppose that the greater part of the energy liberated by the reaction H + Cls went directly into translational and rotational motion of the products. INTRODUCTIOX

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Chemiluminescence

Bronstein¹,

Kricka

Givens

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Chemiluminescence is the emission of light from chemical reactions at ordinary temperatures. The reactions of chemiluminescence produce a reaction intermediate or product in an electronically excited state, and radiative decay of the excited state is the source of the light. Chemiluminescence relates to fundamental molecular interactions and transformations and its study provides access to basic elements of reaction mechanisms and molecular properties, efficient chemiluminescence can provide an emergency or portable light source, chemiluminescence provides means to detect and measure trace elements and pollutants for environmental control or clinically important substances, and classification of the bioluminescent relationship between different organisms defines their biological relationship and pattern of evolution. Liquid‐phase, gas‐phase, and solid‐phase chemiluminescence are discussed as well as bioluminescence, which is characteristic of numerous marine and a few land organisms. The applications of chemical light include marking and illumination and several types of analyses such as flow injection, hplc, direct metal, titration indicators, immunoassay, bacteria and biomass determination, and air pollution.

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Energy distribution among reaction products. Part 1.—The reaction atomic hydrogen plus molecular chlorine

Cited by 76 publications

References 5 publications

Energy Distribution Among Reaction Products. IV. X+HY (X ≡ Cl, Br; Y ≡ Br, I), Cl+DI

Energy Distribution Among Reaction Products. IV. X+HY (X ≡ Cl, Br; Y ≡ Br, I), Cl+DI

The Hydrogen–chlorine System in the Mm Pressure Range: I. Energy Distribution Among Vibrationally Excited States

Chemiluminescence

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