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The rate constant of the reaction of NO3 radical with CF3I was determined by a relative rate method using a Fourier transform infrared (FTIR) spectrometer smog chamber with a long path length gas cell. As a result, the upper limit of the rate constant was determined to be <2.2 × 10−18 cm3 molecule−1 s−1 in 100 Torr of total pressure at 298 K, which suggests that CF3I emitted into the atmosphere accumulates during night. The rate constant of the reaction of NO3 with I(2P3/2) was also measured using time-resolved cavity ring-down spectroscopy. The rate constant showed no pressure dependence in the range of 100-500 Torr of total pressure at 298 K and was determined to be (3.9 ± 1.0) × 10−11 cm3 molecule−1 s−1. The present result is different from the previous ones and is about half of that reported most recently. From this rate constant, it is likely that the reaction of NO3 radical with I(2P3/2) does not have a much influence on the loss of I(2P3/2) and the formation cycle of IO radical in the atmosphere. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 649-660, 2012 [ABSTRACT FROM AUTHOR]

The rate constant of the reaction of NO3 radical with CF3I was determined by a relative rate method using a Fourier transform infrared (FTIR) spectrometer smog chamber with a long path length gas cell. As a result, the upper limit of the rate constant was determined to be <2.2 × 10−18 cm3 molecule−1 s−1 in 100 Torr of total pressure at 298 K, which suggests that CF3I emitted into the atmosphere accumulates during night. The rate constant of the reaction of NO3 with I(2P3/2) was also measured using time-resolved cavity ring-down spectroscopy. The rate constant showed no pressure dependence in the range of 100-500 Torr of total pressure at 298 K and was determined to be (3.9 ± 1.0) × 10−11 cm3 molecule−1 s−1. The present result is different from the previous ones and is about half of that reported most recently. From this rate constant, it is likely that the reaction of NO3 radical with I(2P3/2) does not have a much influence on the loss of I(2P3/2) and the formation cycle of IO radical in the atmosphere. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 649-660, 2012 [ABSTRACT FROM AUTHOR]

Abstract: The reaction of NO3 with C2H5I was studied using time-resolved cavity ring-down spectroscopy. The rate constant of NO3 +C2H5I reaction was determined to be (2.4±0.4)×10−13 cm3 molecule−1 s−1 at 298K and showed no pressure dependence in the range of 25–100Torr of N2 diluent. The determined value of the rate constant suggests that the reaction of NO3 with C2H5I would play an important role in the iodine cycle at night. [Copyright &y& Elsevier]

Abstract: We have applied time resolved cavity ring-down spectroscopy to a kinetic study of the reaction of NO3 with NO2 in 20–700Torr of N2 diluent at 298 and 283K. By fitting the data to Troe’s expression with F c =0.6, the low-pressure and high-pressure limiting rate constants of this reaction were determined to be (298K)=(3.1±0.8)×10−30 cm6 molecule−2 s−1 and (298K)=(1.6±0.3)×10−12 cm3 molecule−1 s−1. These rate constants thus determined were 10–40% larger than those recommend in the NASA/JPL database. [Copyright &y& Elsevier]

Abstract: We have applied cavity ring-down spectroscopy to a kinetic study of the reaction of NO3 with CH2I2 in 25–100Torr of N2 diluent at 298K. The rate constant of reaction of NO3 +CH2I2 is determined to be (4.0±1.2)×10−13 cm3 molecule−1 s−1 in 100Torr of N2 diluent at 298K. The rate constant increases with increasing pressure of buffer gas below 100Torr. The reaction of CH2I2 with NO3 has the potential importance at nighttime in the atmosphere. [Copyright &y& Elsevier]

We have applied cavity ring-down spectroscopy to a kinetic study of the reaction of NO3 with CH3I in 20−200 Torr of N2 diluent at 298 K. The rate constant of the reaction of NO3 + CH3I was determined to be (4.1 ± 0.2) × 10-13 cm3 molecule-1 s-1 in 100 Torr of N2 diluent at 298 K and is pressure-independent. This reaction may significantly contribute to the formation of reactive iodine compounds in the atmosphere. [ABSTRACT FROM AUTHOR]

The adduct formation in the reactions of Cl and Br atom with dimethyl sulfide (DMS) is studied theoretically and experimentally. The rate constants of the forward reaction at several temperatures and pressures are determined from the rise and decay time profiles of the adduct, Cl−DMS, using cavity ring-down laser spectroscopy. The high-pressure limit rate constant for the Cl−DMS adduct formation is determined to be k1a(high) = (2.2 ± 0.2) × 10-10 cm3 molecule-1 s-1. The rate constant of Cl with DMS at atmospheric pressure is k1 = (3.6 ± 0.2) × 10-10 cm3 molecule-1 s-1. Error bars are 1σ. The Arrhenius plot of the forward reaction has a negative temperature dependence for 278−318 K. The calculated equilibrium constants of the reaction Cl and Br with DMS at 300 K are KClDMS = 2.8 × 10-12 and KBrDMS = 7.7 × 10-15 cm3 molecule-1, respectively. The binding energy (D0) is calculated to be 17.7 kcal mol-1 for Cl−DMS, and 14.1 kcal mol-1 for Br−DMS. D0(Br−C) is in fair agreement with the previously reported experimental value, 12 ± 1 kcal mol-1. The results are discussed in comparison with previous experimental reports of the bromine atom adduct, Br−DMS. Atmospheric implications regarding the fate of the X−DMS adducts (X = Cl and Br) in the troposphere are discussed. [ABSTRACT FROM AUTHOR]