Free Radical Processes in the Atmosphere

在1993-1995财政年度进行了下列研究。[1]大气化学中的自由基动物。用脉冲激光光解和光电离质谱相结合的方法测定了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振动激发自由基CF_2^<**> (v2) + O、NH_2^<**> (v2) + NO、HCO^<**> (v_1, v_2, v_3) + O_2的反应速率常数。研究了O_3在Huggins波段（308-326nm）的光解作用。测定了O_3光吸收过程中生成O （^1D）的部分截面。与大气化学有关的模式实验。在6 m^3的光化学反应室中，用长程傅立叶变换红外光谱仪对OH自由基引发异戊二烯的光氧化进行了实验研究。以碳数为基础，估算实际大气中CO产量为30%，估计全球每年异戊二烯CO产量为105 TgCyr^<-1>.2。在6 m^3的可疏散光化学室中，用紫外增强氙弧灯，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对臭氧的破坏作用。紫外光催化卤代烃光解释放的Br原子的链式循环对臭氧的衰变是明显的，尽管链式长度远小于实际的平流层：CFCI_3约为8，CF_3Br约为40。[3]采用红外-紫外双共振（IR-DR） LIF法对低浓度的OH自由基进行了检测。测定的检出限为1.3 * 10^9自由基cm^<-3>.4]。为了分析大气中活性物质在水表面的运移过程，提出了一种新的方法——“碰撞流法”。研究了水对SO^2的吸收，吸收系数与水的pH值密切相关，与温度呈轻微负相关。对羟基自由基的吸收也进行了研究，在中性区典型值为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