α,β-蒎烯气相臭氧化速率常数的测定

对α 蒎烯、β 蒎烯和O3的大气反应进行了初步实验室模拟 ,利用长光程傅里叶变换红外光谱技术结合相对速率法测得在 1 0× 10 5Pa,2 96± 3K条件下 ,α 蒎烯、β 蒎烯和O3气相反应的速率常数分别为2 83× 10 17cm3·molecule-1·s-1和 1 4 8× 10 17cm3·molecule-1·s-1。     

氮氧化物与α-蒎烯、β-蒎烯化学反应的激光磁共振研究

以激光磁共振为手段分别在紫外光照射和火花放电条件下观测了α-蒎烯、β-蒎烯与NO/NO₂的化学反应.得到如下结果:α-蒎烯、β-蒎烯在火花放电条件下可与NO/NO₂发生化学反应,α-蒎烯-NO_x体系的反应比β-蒎烯-NO_x体系的反应完全;α-蒎烯、β-蒎烯在紫外光照射下可与NO_x发生不很剧烈的化变反应.所获得的信息对了解大气化学反应及光化学烟雾有着重要的意义.     

OH与蒎烯醇和柠檬烯醇液相反应动力学的实验和理论研究

蒎烯醇与柠檬烯醇分别是α-蒎烯和柠檬烯大气氧化反应的重要产物,它们的挥发性很低,因而容易进入大气的液相粒子,在颗粒相中被大气氧化剂引发液相氧化反应. 通过实验和理论计算研究,首次在304±3 K和大气压下测得这两种醇与OH的液相反应速率,其速率常数分别为(3.05±0.5)×109和(4.57±0.2)×109 L/(mol·s). 采用量子化学密度泛函法计算这两个液相反应的速率常数,计算中考虑了溶剂化效应的影响,计算结果与实验值符合得较好,并用液质联用和理论计算证实了一些反应产物.     

光敏催化氧化α-蒎烯合成桃金娘烯醛

以α-蒎烯为原料,以卤素灯为光源,在自制光化学反应器中进行反应.研究了α-蒎烯光敏催化氧化制备高附加值桃金娘烯醛的新工艺.考察了光敏催化氧化反应条件对反应转化率和选择性的影响规律.气相色谱分析结果表明:以吡啶-醋酸酐-铜盐为催化剂,在氧流速0.3L/min、原料浓度0.75mol/L、催化剂浓度0.253mol/L、反应温度45℃下反应6h,原料的转化率达97.34％,桃金娘烯醛的选择性可达48.10％.     

姜科植物化学成分的色谱／质谱研究

本文研究了姜科植物１１个样品，提取了挥发油，用色谱／质谱技术从挥发油中鉴定出１００多种成分。其中α－蒎烯，β－蒎烯，莰烯１，８－桉油素，β－水芹烯，柠檬酸，柠檬醛，香叶醇，丁子香酚，芳樟醇，α－姜烯，β－姜烯，α－姜黄烯，β－姜黄烯，石竹烯，姜酮，β－荜澄茄烯，香芹酮，乙酸香叶酯，乙酸芳樟酯等２０种化合物是多数姜科植物挥发油的共同成分。     

吐昔烯衍生物的电荷传输性质

使用密度泛函理论在B3LYP/6-31G**理论水平理论研究吐昔烯(TR)及含不同支链的7个衍生物分子的电荷传输性质。结果表明,吐昔烯及其7个衍生物的空穴传输速率常数在2.71×1012 s-1到1.80×1013 s-1之间,介于六氮杂苯并菲109 s-1和苯并菲1013 s-1之间。8个分子的电子传输速率常数位于1.16×1012 s-1到7.48×1012 s-1之间,大于苯并菲1011 s-1,小于六氮杂苯并菲1013 s-1。在吐昔烯刚性盘上引入羟基和烷氧基,没有改变空穴和电子传输速率常数的数量级。我们计算得到TR(OH)3(OC8H17)3和TR(OC5H11)3的空穴传输速率分别为9.74×10-2 cm2.v-1.s-1和3.78×10-1 cm2.v-1.s-1,与实验测得的两个化合物TR(OH)3(OC10H21)3和TR(OC8H17)3的空穴传输速率接近。     

LP-FTIR跟踪β-蒎烯与臭氧的气相反应研究

利用ＬＰ ＦＴＩＲ系统跟踪β 蒎烯和Ｏ３的气相反应,研究了β 蒎烯和Ｏ３随反应时间的衰减情况,初步确定了反应中诺蒎酮和甲醛随反应时间的生成情况,定性讨论了反应的可能机理,为进一步的定量分析提供了基础。     

分光光度法测定水中的痕量镍

研究了在非离子表面活性剂 Triton X- 10 0存在下 ,在 p H 10 .5的 Na2 B4 O7- Na OH介质中 ,镍 ( )与显色剂 1- ( 4 -硝基苯 ) - 3- ( 2 -吡啶 ) -三氮烯 ( NPPy T)发生灵敏的显色反应 ,生成 1∶ 2的络合物 ,摩尔吸光系数ε=1.0 2× 10 5L· mol-1· cm-1,在 0— 2 0μg/ 2 5 m L范围内服从比耳定律。方法应用于水中微量镍的测定 ,结果令人满意     

LP-FTIR跟踪研究α-蒎烯/O3气相反应

在 1 0× 10 5Pa ,(2 96± 3)K条件下 ,利用长光程傅里叶变换红外光谱技术对α 蒎烯 /O3的气相反应进程进行了原位跟踪 ,对所得的谱图进行了分析 ,初步判断了可能产物 ,并根据分析结果对反应机理进行了推测。     

1-(2,6-二溴-4-硝基苯)-3-(4-硝基苯)-三氮烯与锌的显色反应研究

研究了 1- (2 ,6-二溴 - 4 -硝基苯 ) - 3- (4 -硝基苯 ) -三氮烯 (DBNPNPT)与锌的显色反应。在表面活性剂Triton X- 10 0的存在下 ,p H=9.0— 11.0的 Na2 B4 O7- Na OH介质中 ,DBNPNPT与锌 ( )可生成橙黄色络合物。建立以 5 35 nm为参比波长 ,4 4 0 nm为测定波长的双峰双波长测定法 ,该络合物的表观摩尔吸光系数为 1.34× 10 5L· mol-1· cm-1。对葡萄糖酸锌中的锌直接测定 ,结果令人满意     

The importance of OH radical–neutral low temperature tunnelling reactions in interstellar clouds using a new model

Recent laboratory experiments using a pulsed Laval nozzle apparatus have shown that reactions between a neutral molecule and the radical OH can occur efficiently at low temperatures despite activation energy barriers if there is a hydrogen-bonded complex in the entrance channel which allows the system to tunnel efficiently under the barrier. Since OH is a major radical in the interstellar medium, this class of reactions may well be important in the chemistry that occurs in the gas phase of interstellar clouds. Using a new gas-grain chemical network with both gas-phase reactions and reactions on the surfaces of dust particles, we studied the role of OH–neutral reactions in dense interstellar clouds at 10, 50, and 100 K. We determined that at least one of these reactions can be significant, especially at the lowest temperatures studied, where the rate constants are large. It was found in particular that the reaction between CH₃OH and OH provides an effective and unambiguous gas-phase route to the production of the gaseous methoxy radical (CH₃O), which has been recently detected in cold, dense interstsellar clouds. The role of other reactions in this class is explored.     

基于同步光解的OH自由基标定方法

OH自由基是大气中最重要的氧化剂,准确测量对流层OH自由基的浓度是厘清我国二次污染形成机理的关键.本文介绍了一种基于同步光解的OH自由基便携式标定方法,使用汞灯的185 nm线辐射处于层流状态下的具有一定水汽浓度的合成空气,光解HO2和O2定量产生确定浓度的OH, HO2自由基和O3.开展了臭氧浓度及廓线分布因子P和氧气吸收截面等影响因素的准确测量,降低该标定方法的不确定度.进一步构建便携式标定装置,建立应用于实际外场标定的OH自由基浓度快速获取方法.开展基于激光诱导荧光技术OH自由基(LIF-OH)探测系统的准确标定测试,准确产生3×10^8-2.8×10^9 cm^-3浓度的OH自由基, LIF-OH探测系统的荧光信号与自由基浓度具有非常好的相关性.在综合外场观测(STORM)的应用中该标定装置的不确定度为13.0%,具有良好的稳定性和准确性,可以用于复杂外场环境下LIF-OH系统的快速标定.     

H3O+, NO+和O+·2离子同九种烷氧基醇化合物反应的研究

在用选择离子流动管质谱(SIFT-MS)分析常用指甲油清洗垫发现大量4-丁酸内脂(γ-butyrolactone, GBL)和2-丁氧基乙醇(2-butoxy-1-ethanol)等挥发性气体后, 运用选择离子流动管(SIFT)对H3O , NO 和O ·2离子同九种烷氧基醇化合物(R1-O-R2OH)之间的反应进行了研究. 获得了这些反应在潮湿空气条件下进行的情况, 并运用产物离子水合物的种类和分布来确认产物离子的结构和反应机理. 还研究了在不同载气压力下进行的反应. 结果表明, 这些化合物同H3O 和NO 的反应都是先生成初生态离子-分子络合物, (H3O .M)*和(NO .M)*, 然后经不同反应渠道生成各种离子产物. 这些初生态络合物同反应体系中存在的气体分子(如氦气, 氮气和氧气分子)的碰撞对最终离子产物的形成和分布也有影响. 这些化合物同O2 ·反应会生成各种离解碎片离子, 但不能确定这些离子是否经由初生态络合物(O2 ·.M)*生成. 该项研究提供了用SIFT-MS在空气和潮湿气体中分析这些化合物所需的反应速率常数和离子产物等动力学数据, 并将进一步应用到药物成瘾及滥用和呼吸道疾病的诊断和分析等领域.     

脉冲电晕放电电子能量及OH,O或O3对NO氧化的光谱学研究

采用发射光谱法测量了线板式脉冲电晕放电中激发态氮气分子N2*和离子N2+的光谱强度,并与数值计算获得的结果进行对比,确定放电电场的空间分布及平均电子能量。水平与竖直方向离开线电极0～2cm,随着距离的增加,平均电子能量和电场均呈先减后增的变化趋势;放电电场变化范围11.05～19.6MV.m-1,对应的平均电子能量的变化范围10.10～13.92eV。这一能量水平的电子足以与O2,H2O分子碰撞产生O,OH自由基,并进一步反应生成O3。在NO氧化过程中,NO可与OH自由基共存,但不能与O3共存;且O3或O氧化NO的效率高于OH自由基,推断O3或O在NO的氧化过程中起关键作用。     

Reaction of OH radical and ozone with methyl salicylate – a DFT study

A theoretical study on the reaction mechanism of methyl salicylate (MeSA), a green leaf volatile organic compound with OH radical and ozone, has been carried out using density functional theory methods using B3LYP, M06‐2X and MPW1K functionals with 6‐311++G(d,p) basis set. The atmospheric degradation pathways of MeSA with OH radical are studied under two different pathways, viz. H‐atom abstraction and electrophilic addition of OH radical. The hydrogen abstraction from –OH group is found to be the dominant reaction channel with small barrier height. Likewise, the electrophilic addition of OH radicals at the para position of MeSA is found to be favourable rather than the ortho and meta positions because of the small barrier height. However, the reaction of MeSA with respect to the addition of O₃ is initiated only through the cycloaddition to the C?C bond, resulting in primary ozonide. The Arrhenius plot for most of the addition reaction shows positive temperature dependence, while for the abstraction reaction, it exhibits negative temperature dependence over the temperature range of 278–350 K. The calculated theoretical rate constants are in good agreement with available experimental data. Overall, the addition of both OH radical and ozone possesses ability to degrade MeSA, but slower when compared with the Cl radical. Copyright © 2015 John Wiley & Sons, Ltd.     

Mathematical analysis of positive pulsed corona discharge processemployed for removal of nitrogen oxides

A mathematical model was proposed to describe the behaviour of the removal of nitrogen oxides (NO_x) in a positive pulsed corona discharge reactor. The proposed model takes into account radical production at each pulsing and subsequent radical utilization for NO_x removal. The production efficiencies of radicals such as O, OH, H, and N were derived by considering direct electron impact on dissociation of gaseous molecules, followed by excitation transfer reactions of excited oxygen atoms. The production efficiencies of those species were used for the model calculations. The proposed model could adequately predict the experimental data. Of the active species present, the ozone (O₃) produced by the reaction of O radical with oxygen was found to play the crucial role in oxidation of NO to NO₂ , both theoretically and experimentally     

基于CRDS系统对北京夜间大气边界层NO_3自由基观测与分析

夜间大气NO3自由基的氧化能力相当于白天OH自由基,鉴于NO3自由基在大气反应过程中的关键作用,准确测量其浓度及研究其夜间大气化学过程具有重大意义。采用以二极管激光器为光源(中心波长为662nm,半高宽0.3nm),两块高反射率镜片(R≥99.998 5%)形成的腔体为光学共振腔,有效光程达到约20km的腔衰荡光谱系统(CRDS)对夜间大气NO3自由基进行测量,并且针对秋冬季交通繁忙区域夜间大气边界层NO3自由基化学过程进行研究。采用该系统于2014年10月29日—11月15日在北京市中国科学院大学校园开展了NO3自由基连续外场观测实验,观测期间NO3自由基浓度相对较低,最大浓度约为50pptv,平均值为10pptv。并结合NO2,NO和O3等相关辅助数据对测量结果进行分析,分析表明在观测期间NO3自由基产率为0.04~1.03pptv·s-1,平均寿命约为68s。并且近一步分析了观测期间大气NO3自由基损耗途径,探讨了不同湿度及颗粒物浓度对其损耗的影响。即观测期间当大气中RH≥60%,PM2.5浓度大部分大于60μg·m-3时,ln(τss(NO3))与ln(NO2)的相关性达到0.79,大气中NO3自由基损耗主要以间接为主;然而在RH≤40%,PM2.5浓度大部分小于60μg·m-3时,因测量点靠近国道受局地污染源影响,直接损耗较显著;当大气中40%RH60%时,直接损耗与间接损耗途径都存在且不可忽视。     

Rate coefficients for the gas-phase reaction of OH radical with α-pinene: an experimental and computational study

The rate coefficient for the gas-phase reaction of OH radical with α-pinene was measured at 298 K using relative rate methods, with propylene as a reference compound. The ratio of the rate coefficient for the reaction of OH radicals with α-pinene to that of with OH radicals with propylene was measured to be 1.77 ± 0.21. Considering the absolute value of the rate coefficient of the reaction of OH radicals with propylene as (3.01 ± 0.42)×10^?11 cm³ molecule^?1 s^?1, the rate coefficient for the reaction of OH radicals with α-pinene was determined to be (5.33 ± 0.79)×10^?11 cm³ molecule^?1 s^?1. To gain a deeper insight into the reaction mechanism, theoretical calculations were also carried out on this reaction. The rate coefficient of OH radical with α-pinene was calculated using canonical variational transition state theory with small-curvature tunnelling. The kinetics data obtained over the temperature range of 200–400 K were used to derive the Arrhenius expression: k(T) = 3.8×10^?28 T^5.2 exp[2897/T] cm³ molecule^?1 s^?1. The OH-driven atmospheric lifetime (τ) and ozone formation potential of α-pinene were calculated and reported in this work.     

Mechanism and kinetics of the atmospheric degradation of 2-formylcinnamaldehyde with O3 and hydroxyl OH radicals – a theoretical study

In the present investigation, the reaction mechanism and kinetics of 2-formylcinnamaldehyde (2-FC) with O₃ and hydroxyl OH radicals were studied. The reaction of 2-FC with O₃ radical are initiated by the formation of primary ozonide, whereas the reaction of 2-FC with the hydroxyl OH radical are initiated by two different ways: (1). H-atom abstraction by hydroxyl OH radical from the –CHO and –CH = CHCHO group of 2-FC (2). Hydroxyl OH addition to the –CH = CHCHO group to the ring-opened 2-FC. These reactions lead to the formation of an alkyl radical. The reaction pathways corresponding to the reactions between 2-FC with O₃ and hydroxyl OH radicals have been analysed using density functionals of B3LYP and M06-2X level of methods with the 6-31+G(d,p) basis set. Single-point energy calculations for the most favourable reactive species are determined by B3LYP/6-311++G(d,p) and CCSD(T)/6-31+G(d,p) levels of theory. From the obtained results, the hydroxyl OH addition at C8 position of 2-FC are most favourable than the C9 position of 2-FC. The subsequent reactions of the alkyl radicals, formed from the hydroxyl OH addition at C8 position, are analysed in detail. The individual and overall rate constant for the most favourable reactions are calculated by canonical variational transition theory with small-curvature tunnelling corrections over the temperature range of 278–350 K. The calculated theoretical rate constants are in good agreement with the available experimental data. The Arrhenius plot of the rate constants with the temperature are fitted and the atmospheric lifetimes of the 2-FC with hydroxyl OH radical reaction in the troposphere calculate for the first time, which can be applied to the study on the atmospheric implications. The condensed Fukui function has been verified for the most favourable reaction sites. This study can be regarded as an attempt to investigate the O₃-initiated and hydroxyl OH-initiated reaction mechanisms of 2-FC in the atmosphere.