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A-1.5.1 Heterogeneous chemistry of chlorine contained molecules and radicals

[Contact Person]

Takashi Imamura
Team Leader
Ozone Layer Research Team
Global Environment Research Group
National Institute for Environmental Studies
Environment Agency
16-2 Onogawa, Tsukuba, Ibaraki, 305-0053, Japan
Phone +81-298-50-2406 Fax +81-298-50-2579

Total Budget for FY1996-FY1998

39,171,000 Yen (FY1998 ; 13,003,000 Yen)

Abstract

(1) A new detector of chlorine molecule using a spectroscopic method was developed. The characteristics of the detector are the following: (i) Cl₂ molecule can be detected by monitoring the UV emission at 257 nm following the excitation by the Kr resonance line (123.6 nm). (ii) Cl₂ can be detected in air. (iii) The most effective condition for the total pressure of air is 150 Torr. (iv) The linearity of the signal is guaranteed up to 100 ppmv of Cl₂ in air. (v) The detection limit is about 10 ppbv for 60 s accumulation. (vi) The interference from other atmospheric trace gases seems to be negligible. (2) The uptake coefficients of I₂ and NO onto aqueous solution were measured by using an impinging flow reactor and determined to be 2 x 10^-4 and < 2 x 10^-4, respectively. The uptake of acetone onto sulfuric acid was investigated using a wetted-wall flow reactor and was found to be limited by solubility. (3) Photodissociation of methyl iodide in the atmospheric window region, 190-210 nm, was investigated by using a time-resolved photoionization mass spectrometer. It was found that HI molecule as well as CH₃ and I was produced in the laser photolysis at 193 um. The formation yield of HI was determined to be 0.4±0.1.

[Key Words]

heterogeneous reactions, chlorine molecule, uptake coefficient, solubility, methyl iodide