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 (435Kb)
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47,395,000 Yen (FY1995; 12,941,000 Yen)
¡¡The following two studies were carried out in order to understand chemical processes among tropospheric trace gases.
[1] Rate Constants for Reactions of¡¡Substituted Methyl Radicals with O2
Reactions of the substituted methyl radicals CH2OCH3, CH2NH2, CH2I, and CH2CN with O2 have been studied by a combination of pulsed laser photolysis and photoionization mass spectrometry. The reactivity is greatly enhanced by substituting one of the hydrogen atoms of a methyl radical with the electron-donating substitutents, -OCH3 and -NH2. The rate constants obtained at 298.5K were (6.5 ¡Þ 0.7)¡ß 10-12 and (3.5 ¡Þ 0.4)¡ß 10-11 in units of cm3 molecule-1 s-1 for CH2OCH3 and CH2NH2, respectively. The reactivity is reduced for CH21 and CH2CN, which have the electron-withdrawing substitutents, -I and -CN. The rate for the reaction of CH21 with O2 was (1.6¡Þ0.2)¡ß 10-12 cm3 molecule-1 s-1. The reactivity of substituted methyl radicals was discussed by the correlation with ionization potentials and electronegativities of radicals.
[2] Measurements of Rate Constants for HO2+NO and NH2+NO Reactions.
Absolute rate constants for HO2+NO, NH2+NO reactions were measured by a photoionization mass spectrometry coupled with a laser flash photolysis. HO2, and NH2 radicals were photoionized by an Ar resonance lamp and were detected as their parent ions (HO2+ and NH2+). The rate constants were determined to be
k (HO2 + NO) = (6.5¡Þ2.0)10-12 cm3 molecule-1 s-1
k (NH2 + NO) = (1.9¡Þ0.3)10-11 cm3 molecule-1 s-1
Both rates are consistent with those previously reported.
Free Radical, photoionization Mass Spectrometry, Rate Constant, HO2, NH2, Substituted Methyl Radical