Kinetics of the reaction Cl + HO₂ = HCl + O₂, using molecular modulation spectrometry

Abstract

The rate constant for the reaction (I), C1+ HOz -HCI + 0 2 , was measured using molecular modulation spectrometry to investigate HOz radical kinetics in the modulated photolysis of ClyH2-02 mixtures at 760 torr pressure. HOz was monitored directly in absorption at 220 nm, and k l was determined from computer simulations of the observed kinetic behavior of HOz, using a simple chemical model. The results gave kJk4 = 3.OtFh exp[+(2120 f 370)/T]where k s is the rate constant for the reaction of C1 with Hz. A consensus value of kq gave kl = 6.9 X lo-" cm3/molecule sec, independent of temperature in the range of 274338 K with an overall uncertainty of f50%. The relative importance of reaction (1) for the conversion of C1 to HC1 in the stratosphere is discussed briefly.

Effects of water, ammonia and formic acid on HO2 + Cl reactions under atmospheric conditions: competition between a stepwise route and one elementary step

“…The potential importance of the Cl reaction with the HO 2 radical has led to a number of publications and, as a result, the kinetics of the HO 2 + Cl reaction have been studied experimentally for a range of temperatures. 8,[13][14][15][16] Lee et al 16 measured the rate constant of eqn (1) in a discharge-ow system with far infrared laser magnetic resonance within the temperature range 250-420 K. Similarly, Dobis et al 8 used mass spectrometry to measure the rate constant ((4.45 AE 0.06) Â 10 À11 cm 3 per molecule per s) of the reaction of eqn (1) in the temperature range 243-368 K. Both of these investigations showed that the rate constant in eqn (1) does not change within the measured temperature range. In another experiment, Hickson et al 9 used the discharge-ow resonance uorescence technique coupled with infrared diode laser spectroscopy to measure the rate constant for the reaction in eqn (1) within the temperature range 226-336 K. Their results show that the rate constant in eqn (1) derived from kinetic experiments expressed in Arrhenius form was (1.6 AE 0.2) Â 10 À11 exp[(249 AE 34)/T] cm 3 per molecule per s. The theoretical aspect of the kinetics and mechanism for the reaction of eqn (1) have not yet been investigated.…”

A Study of Gas-Phase Mercury Speciation Using Detailed Chemical Kinetics

“…As an example, an increase in the value of the factor from 4.1 × 10 13 to 4.1 × 10 15 resulted in a small increase in Hg conversion to 0.1%. As the rate of this reaction has been measured experimentally, 17,18 it is unclear whether such modifications can be justified.…”

Kinetics and mechanism of the reaction of Cl atoms with HO2 radicals

“…These results are in good agreement with those obtained from HO 2 decay kinetics in excess of Cl. All the results for k 1 from the present work are shown in Figure 5 together with the data obtained in previous temperature-dependent studies of reaction (1) [5,8,9]. The continuous straight line in Figure 5, resulting from the least-squares analysis of the present data, provides the following Arrhenius expression: …”