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

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

Rate constant for the reaction of hydroxyl radical with formaldehyde over the temperature range 228-362 K

Absolute rate constants for the reaction OH ? H2CO measured over the temperature range 228-362 K using the flash photolysis-resonance fluorescence technique are given. The results are independent of variations in H2CO concentration, total pressure Ar concentration, and flash intensity (i.e., initial OH concentration). The rate constant is found to be invariant with temperature in this range, the best representation being k sub 1 = (1.05 ? or - 0.11) x 10 to the 11th power cu cm molecule(-1) s(-1) where the error is two standard deviations. This result is compared with previous absolute and relative determinations of k sub 1. The reaction is also discussed from a theoretical point of view

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

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

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

Upper atmosphere research: Reaction rate and optical measurements

The objective is to provide photochemical, kinetic, and spectroscopic information necessary for photochemical models of the Earth's upper atmosphere and to examine reactions or reactants not presently in the models to either confirm the correctness of their exclusion or provide evidence to justify future inclusion in the models. New initiatives are being taken in technique development (many of them laser based) and in the application of established techniques to address gaps in the photochemical/kinetic data base, as well as to provide increasingly reliable information