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Michael, J. V.

Publications and source records attributed to Michael, J. V..

32 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Absolute rate of the reaction of bromine atoms with ozone from 200 to 360 K

The rate constant for the reaction Br + O3 yields BrO + O2 has been measured from 200 to 360 K by the technique of flash photolysis coupled to time resolved detection of bromine atoms by resonance fluorescence (FP-RF). Br atoms were produced by the flash photolysis of CH3Br at a wavelength of 165 nm. O3 concentration was monitored continuously under reaction conditions by absorption at 253.7 nm. At each of five temperatures the results were independent of substantial variations in O3 concentration, total pressure (Ar), and limited variations in flash intensity (i.e., initial Br concentration). The measured rate constants obey the Arrhenius expression, k = (7.74 plus or minus 0.50) x 10 to the -12th exp(-603 plus or minus 16/T) cu cm/molecule/sec, where the error quoted is two standard deviations.

Michael, J. V.↗
NASA NTRS1978

Absolute rate of the reaction of hydrogen atoms with ozone from 219-360 K

Absolute rate constants for the reaction of atomic hydrogen with ozone were obtained over the temperature range 219-360 K by the flash photolysis-resonance fluorescence technique. The results can be expressed in Arrhenius form by K = (1.33 plus or minus 0.32)x10 to the minus 10 power exp (-449 plus or minus 58/T) cu cm/molecule/s (two standard deviations). The present work is compared to two previous determinations and is discussed theoretically.

Lee, J. H.↗
NASA NTRS1978

Absolute rate of the reaction of atomic hydrogen with ethylene from 198 to 320 K at high pressure

The rate constant for the H+C2H4 reaction has been measured as a function of temperature. Experiments were performed with high pressures of Ar heat bath gas at seven temperatures from 198 to 320 K with the flash photolysis-resonance fluorescence (FP-RF) technique. Pressures were chosen so as to isolate the addition rate constant k1. The results are well represented by an Arrhenius expression. The results are compared with other studies and are theoretically discussed.

Lee, J. H.↗
NASA NTRS1978

Absolute rate of the reaction of bromine atoms with ozone from 200-360 K

The rate constant for the reaction Br + O3 yields BrO + O2 was measured from 200 to 360 K by the technique of flash photolysis coupled to time resolved detection of bromine atoms by resonance fluorescence (FP-RF). Br atoms were produced by the flash photolysis of CH3Br at lambda 165nm.O3 was monitored continuously under reaction conditions by absorption at 253.7 nm. At each of five temperatures the results were independent of substantial variations in O3, total pressure and limited variations in flash intensity. The measured rate constants obeyed the Arrhenius expression, where the error quoted is two standard deviations. Results are compared with previous determinations which employed the discharge flow-mass spectrometric technique.

Michael, J. V.↗
NASA NTRS1977

Absolute rate constant for the reaction of atomic chlorine with hydrogen peroxide vapor over the temperature range 265-400 K

Rate constants for the reaction of atomic chlorine with hydrogen peroxide were measured from 265-400 K using the flash photolysis-resonance fluorescence technique. Analytical techniques were developed to measure H2O2 under reaction conditions. Due to ambiguity in the interpretation of the analytical results, the data combine to give two equally acceptable representations of the temperature dependence. The results are compared to previous work at 298 K and are theoretically discussed in terms of the mechanism of the reaction. Additional experiments on the H + H2O2 reaction at 298 and 359 K are compared with earlier results from this laboratory and give a slightly revised bimolecular rate constant.

Michael, J. V.↗
NASA NTRS1977

Absolute rate of the reaction of Cl/2P/ with methane from 200-500 K

Rate constants for the reaction Cl + CH4 yields HCl + CH3 were measured in the range 200-500 K by the plot flash photolysis-resonance fluorescence technique. An Arrhenius plot of the mean rate constant observed at 14 equally spaced temperatures is best fit by the expression k = 5.44 times 10 to the minus 19th times T to the exponent 2.50 times exp(-608/T) cu cm per molecule per sec. Appropriate expressions are also given for the rate constant in the two ranges 200-299 K and 299-500 K. These results are compared with a number of other existing determinations of the rate constant by other methods and in different temperature ranges. Most discrepancies are attributed to the nonlinear Arrhenius behavior.

Whytock, D. A.↗
NASA NTRS1976

Absolute rate of the reaction of Cl(p-2) with molecular hydrogen from 200 - 500 K

Rate constants for the reaction of atomic chlorine with hydrogen are measured from 200 - 500 K using the flash photolysis-resonance fluorescence technique. The results are compared with previous work and are discussed with particular reference to the equilibrium constant for the reaction and to relative rate data for chlorine atom reactions. Theoretical calculations, using the BEBO method with tunneling, give excellent agreement with experiment.

Whytock, D. A.↗
NASA NTRS1976

Absolute rate constants for O + NO + M /= He, Ne, Ar, Kr/ yields NO2 + M from 217-500 K

Rate constants for the reaction O + NO + M yields NO2 + M have been obtained at temperatures from 217-500 K in four different rare gases by a method combining flash photolysis with time resolved detection of O(3-P) by resonance fluorescence. The measured rate constants in Arrhenius form are (10.8 plus or minus 1.2) x 10 to the -33rd exp(1040 plus or minus 60/1.987 T) for helium; (9.01 plus or minus 1.16) x 10 to the -33rd exp(1180 plus or minus 70/1.987 T) for argon; (9.33 plus or minus 1.10) x 10 to the -33rd exp(1030 plus or minus 60/1.987 T) for neon; and (9.52 plus or minus 1.10) x 10 to the -33rd exp(1140 plus or minus 70/1.987 T) for krypton in units of cm to the 6th/sq molecule/s.

Michael, J. V.↗
NASA NTRS1976

Absolute rate of the reaction of C l(2P) with methane from 200-500 K

Rate constants for the reaction of atomic chlorine with methane have been measured from 200-500K using the flash photolysis-resonance fluorescence technique. When the results from fourteen equally spaced experimental determinations are plotted in Arrhenius form a definite curvature is noted. The results are compared to previous work and are theoretically discussed.

Whytock, D. A.↗
NASA NTRS1976

Absolute rate of the reaction of O/3-P/ with hydrogen sulfide over the temperature range 263 to 495 K

The technique of flash photolysis coupled with time resolved detection of O via resonance fluorescence has been used to obtain rate constants for the reaction of O(3-P) with H2S at temperatures from 263 to 495 K and at pressures in the range 10-400 torr. Under conditions where secondary reactions are avoided, the measured rate constants for the primary step obey the Arrhenius equation k = (7.24 plus or minus 1.07) x 10 to the -12th exp(-3300 plus or minus 100/1.987 T) cu cm/molecules/s. Experiments with D2S show that the reaction exhibits a primary isotope effect, in support of a hydrogen abstraction mechanism.

Whytock, D. A.↗
NASA NTRS1976

Absolute rate constants for O + NO + N2 yields NO2 + N2 from 217-500 K

Rate constants for the reaction O + NO + N2 yields NO2 + N2 from 217 to 500 K were obtained by a method combining the flash photolysis of NO with the time resolved detection of O by means of resonance fluorescence. The rate constants were found to obey the Arrhenius equation k = (15.5 plus or minus 2.0) x 10 to the -33rd exp((1160 plus or minus 70)/1.987 T) cm to the 6th/squared molecule/s, while the temperature dependence of k is described by k = 3.80 x 10 to the -27th/T to the 1.82 cm to the 6th/squared molecule/s.

Whytock, D. A.↗