| Co-Investigator(Kenkyū-buntansha) |
MATUMI Yutaka Hokkaido University, Associate Professor, 電子科学研究所, 助教授 (30209605)
AKIMOTO Hajime The University of Tokyo, Professor, 先端科学技術センター, 教授 (50101043)
YAMASAKI Katsuyoshi Niigata University, Associate Professor, 理学部, 助教授 (90210385)
KODA Seiichiro Dept.of Chemical System engineering, The University of Tokyo, Professor, 工学部, 教授 (10011107)
SHIBUYA Kazuhiko Tokyo Institute of Technology, Associate Professor, 理学部, 助教授 (30126320)
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| Research Abstract |
The following studies were carried out during the 1993-1995 fiscal years.
1] Free radical kinetirs related to atmospheric chemistry
1. Rate constants for reactions of RO_2 + NO,CH_2X + O_2, HS+O,NH_2+O,NHO+O,and CH_3 + N have been measured by a combination of pulsed laser photolysis and photoionization mass spectrometry.
2. Rate constants for reactions of the vibrationally excited free radicals, such as CF_2^<**> (v2) + O,NH_2^<**> (v2) + NO,HCO^<**> (v_1, v_2, v_3) + O_2 were determined by using laser induced fluorescence technique.
3. Photodissociation of O_3 at Huggins band (308-326nm) has been studied. The partial cross sections for the O (^1D) production in the photoobsorption of O_3 were determined.
2] Model experiments related to atmospheric chemistry.
1. The OH radical-initiated photooxidation of isoprene has been investigated experimentally by a 6-m^3 photochemical reaction chamber equipped with a long path length Fourier transform infrared spectrometer. The CO yield in the real atm
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osphere was evaluated as 30% on the carbon number basis, and global annual CO production from isoprene was estimated to be 105 TgCyr^<-1>.
2. Ozone destruction by CFC's (CFCl_3 and CF_2Cl_2), BFC's (CF_3Br and C2H_4Br_2), HCFC's (CH_3CCl_2F,CF_3CHCl_2, and CF_3CHCl) and CH3Br was demonstrated using a 6-m^3 evacuable photochemical chamber equipped with UV-enhanced Xe arc lamps. The decay of ozone by a catalytic cycle involving CI of Br atoms released from the photolysis of halocarbons by UV light was evident, although the chain length was far less than in the real stratosphere : It was about 8 for CFCI_3 and 40 for CF_3Br.
3] Development of a monitoring method of OH and HO_2
Detection of OH radicals in low concentration was carried out using an infrared-ultraviolet double resonance (IR-DR) LIF method. The detection limit was determined to be 1.3 * 10^9 radical cm^<-3>.
4] Heterogeneous reactions in the atmosphere.
In order to analyze the transport processes of active species from the bulk atmosphere across the aqueous surfaces, a novel method, named as "impinging flow method" was developed. The uptake of SO^2 by the water was studied and the uptake coefficient was strongly dependent on the pH value of the water and showed a slightly negative temperature dependence. The uptake of OH radicals was also studied and the typical value was 0.006 in the neutral region. Less
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