Temperature and Pressure Dependence Study of the Reaction of IO Radicals with Dimethyl Sulfide by Cavity Ring-Down Laser Spectroscopy

Abstract

The reaction of IO radicals with dimethyl sulfide was studied using cavity ring-down laser spectroscopy. The reaction rate constant shows both a temperature and pressure dependence. At 100 Torr total pressure, the reaction has reached its high-pressure limit and has a rate constant of (2.5 ( 0.2) × 10 -13 molecule -1 cm 3 s -1 at 298 K. On the basis of the Arrhenius plot in the region of 273-312 K, the reaction has a negative activation energy (E a ) -18.5 ( 3.8 kJ mol -1 ). The atmospheric implications of these findings are discussed. In light of these new data, DMS oxidation by IO can compete with oxidation by the hydroxyl radical in the marine boundary layer. Quoted uncertainties are one standard deviation from regression analysis.

Theoretical study of adducts of dimethyl sulfide with hydroperoxyl and hydroxyl radicals

“…It has also been shown that DMS is oxidized by chlorine atom, and that this is probably important in the atmosphere [9][10][11]. DMS oxidation by halogen oxides in the gas phase [12][13][14][15], and via heterogeneous reactions [16], for example, with aqueous phase ozone (O 3 ) [17,18], may also be important. Some model calculations over predict the concentration of DMS in the marine boundary layer (MBL), suggesting that there may be a missing sink [19].…”

Tropospheric Halogen Chemistry

“…The total number and size distribution of CCNs determine the microphysical and therefore also radiative properties of clouds. These slow rate coefficients have been challenged by Nakano et al (2003), suggesting a significantly faster rate coefficient, but Gravestock et al (2005) and Dillon et al (2006) have confirmed the earlier, slower-rate coefficients. DMS is the most important precursor for SO 2 and sulfate aerosol in the remote MBL.…”

Environmental effects of large igneous province magmatism: a Siberian perspective

“…(Table: [78]). Nakano et al [943] have employed a laser flash photolysiscavity ring down spectroscopy technique to investigate the temperature and pressure dependence of the rate constant. These investigators report that the 298 K rate constant increases from 1 to 25 x 10 (Table: 06-2, Note: 06-2) Back to Table I61.…”