Free Radical Processes in the Atmosphere

大气中的自由基过程

基本信息

批准号：
05237106
负责人：
WASHIDA Nobuaki
金额：
$ 48.32万
依托单位：
National Institute for Environmental Studies
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

项目摘要

The following studies were carried out during the 1993-1995 fiscal years.1] Free radical kinetirs related to atmospheric chemistry1. 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 … More 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_2Detection 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

1993-1995财年进行了以下研究：1]与大气化学相关的自由基动力学1．RO_2+NO、CH_2X+O_2、HS+O、NH_2+O、NHO+O和CH_3 + N 已通过脉冲激光光解和光电离质谱法的组合进行测量。2．采用激光诱导荧光技术测定 CF_2^<**> (v2) + O,NH_2^<**> (v2) + NO,HCO^<**> (v_1, v_2, v_3) + O_2 3研究了 O_3 在 Huggins 波段（308-326nm）的光解离，研究了 O_3 光吸收中 O (^1D) 产生的部分截面。 2]与大气化学相关的模型实验1.通过配备长光程傅里叶变换红外光谱仪的6-m^3光化学反应室对OH自由基引发的异戊二烯光氧化反应进行了实验研究。根据碳数计算，实际大气压为 30%，全球每年从异戊二烯产生的二氧化碳估计为 105 TgCyr^<-1>.2。使用配备紫外线增强型氙弧灯的 6 m^3 真空光化学室演示了 CFC（CFCl_3 和 CF_2Cl_2）、BFC（CF_3Br 和 C2H_4Br_2）、HCFC（CH_3CCl_2F、CF_3CHCl_2 和 CF_3CHCl）和 CH3Br 的破坏。通过催化循环产生臭氧紫外光光解卤化碳释放的 Br 原子的 CI 很明显，尽管链长远小于真实平流层中的链长：CFCI_3 约为 8，CF_3Br 约为 40。3] OH 监测方法的开发HO_2采用红外-紫外双共振(IR-DR)LIF法检测低浓度的OH自由基，测定限为1.3 * 10^9自由基cm^<-3>.4]大气中的非均相反应。为了分析活性物质从本体大气穿过水表面的传输过程，一种新颖的方法，称为“冲击流法”研究了水对 SO^2 的吸收，吸收系数强烈依赖于水的 pH 值，并表现出轻微的负温度依赖性。还研究了 OH 自由基的吸收，典型值为中性区小于 0.006。