Free Radical Processes in the Atmosphere

在1993-1995财政年度进行了下列研究。1与大气化学有关的自由基动力学1。采用脉冲激光光解和光电离质谱联用技术，测定了RO_2 + NO、CH_2X + O_2、HS+ O、NH_2 +O、NHO+O和CH_3 + N反应的速率常数.用激光诱导荧光技术测定了CF_2^**>（v_2）+O，NH_2 ^**>（v_2）+ NO，HCO^**>（v_1，v_2，v_3）+ O_2等振动激发自由基反应的速率常数.本文研究了O_3分子在Huggins带（308- 326 nm）的光解。确定了O_3光吸收过程中O（^1D）产生的部分截面。2]与大气化学有关的模式实验。在6 m^3的光化学反应室中，用长光程傅里叶变换红外光谱仪研究了OH自由基引发的异戊二烯光氧化反应。在真实的大气压下的CO产率 ...更多信息 根据碳数计算，大气层的二氧化碳排放量为30%，全球每年由异戊二烯产生的二氧化碳排放量估计为105 TgCyr^<-1>. 2。利用一个6 m^3的真空光化学室，用紫外增强的氙灯，演示了CFC’s（CFCl_3和CF_2Cl_2）、BFC’s（CF_3Br和C2H_4Br_2）、HCFC’s（CH_3CCl_2F，CF_3CHCl_2和CF_3CHCl）和CH 3Br对臭氧的破坏。臭氧的衰减是通过一个催化循环进行的，其中涉及到卤烃在紫外光作用下光解释放出的溴原子的氯原子化，尽管其链长远小于真实的平流层中的链长：用红外-紫外双共振法测定了低浓度OH自由基的含量。IR-DR）LIF方法。检测限为1.3 * 10^9自由基cm^<-3>4]为了研究大气中活性组分在水表面的迁移过程，发展了一种新的方法--撞击流法。研究了水对SO^2的吸收，吸收系数强烈依赖于水的pH值，并显示出轻微的负温度依赖性。OH自由基的吸收也进行了研究，在中性区域的典型值为0.006。少

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