双分子水和氨气催化CF3OH分子裂解的理论研究

利用G3和CBS-QB3的理论方法研究CF₃OH分子裂解成FCFO和HF,并考虑大气中双分子和氨气对CF₃OH分子裂解的催化作用. 理论计算表明：由于在G3的理论水平下,计算的能垒为188.52 kJ/mol,所以CF₃OH分子在大气条件下不可能发生单分子裂解;当氨气和双分子水被加入时,能垒都被降到25.08 kJ/mol,起了强的催化作用. 除此之外,应用过渡态理论对速率常数进行了计算,计算结果表明：氨气催化CF₃OH分子的速率常数是单分子和双分子催化CF₃OH分子裂解速率常数的10⁹和10⁵倍. 考虑到大气中这些物质的浓度,计算结果预测了氨气催化CF₃OH分子裂解在大气中起到重要的作用.     

CHCl3电子吸附速率常数的离子迁移谱

利用电晕放电离子迁移谱, 使用高纯氮气作为载气和迁移气体, 研究了电场强度在200～500 V/cm变化时CHCl₃的解离电子吸附速率常数, 得到样品所对应的电子吸附速率常数为1.26×10^-8～8.24×10^-9 cm³/(molecules s)．利用该装置测量了固定电场下,样品的电子吸附速率常数与样品浓度之间的关系．此外利用所获得的离子迁移谱图得到了不同电场强度下Cl^-与CHCl₃之间的离子分子反应速率常数.     

LiNbO3和LiTaO3晶体Er3+/Yb3+掺杂水热外延层室温吸收光谱分析

本文引入与浓度和厚度有关的k_NL待定参数, 在J-O理论基础上, 对Er³⁺/Yb³⁺掺杂的LiNbO₃和LiTaO₃单晶衬底上 的多晶水热外延样品进行了基于吸收光谱的拟合计算. LiNbO₃:Ω₂=2.34× 10^-20 cm², Ω₄=0.77× 10^-20 cm², Ω₆=0.31×10^-20 cm², k_NL=4.32× 10^-2 mol·m^-2. LiTaO₃:Ω₂=1.68×10^-20 cm², Ω₄=0.84×10^-20 cm², Ω₆=0.45×10^-20 cm², k_NL=9.17×10^-3 mol· m^-2. 该方法可尝试推广到粉体或胶体等难以直接获得浓度和厚度数据的体系. 经上转换发光测试及光谱参数计分析认为Er³⁺/Yb³⁺离子的掺杂浓度比为1:1的情况下, 样品呈现绿色上转换发光光谱; 可尝试以降低基质声子能量的方法提高⁴I_13/2能级 对²H_11/2和⁴S_3/2能级的量子剪裁效率.     

瞬态磷光发射光谱研究阿替洛尔与单线态氧反应的动力学

药物活性化合物阿替洛尔是一种β受体阻滞剂,若将其排放到地表水资源中会对人类健康和生态系统产生不利的影响. 受光驱动的直接光降解以及间接光降解法可以有效去除环境中的阿替洛尔. 在间接光降解方法中,¹O₂是降解阿替洛尔这类污染物的重要活性物种. 然而,关于阿替洛尔与¹O₂反应动力学的信息还比较缺乏,二者间的反应速率常数仍存在争议. 本文通过直接观察¹O₂在1270 nm处衰减动力学来研究阿替洛尔与¹O₂在不同溶剂中的反应速率常数：在重水中为7.0×10⁵ (mol/L)^-1·s^-1,在乙腈中为8.0×10⁶ (mol/L)^-1·s^-1,在乙醇中为8.4×10⁵ (mol/L)^-1·s^-1. 在极性强、给氢能力弱的溶剂中阿替洛尔与¹O₂的反应速率常数更大. 这些结果对光降解阿替洛尔等β受体阻滞剂提供相关动力学信息.     

青蒿素光化学合成中二氢青蒿酸与单线态氧反应的动力学研究

青蒿素是一种优异的抗疟药，广泛用于临床医学. 但由于青蒿素天然来源的限制，青蒿素的化学合成一直受到高度关注. 二氢青蒿酸是合成青蒿素的关键前体. 二氢青蒿酸与单线态氧反应形成过氧化物是青蒿素光化学制备中的关键步骤，制约着青蒿素化学合成的产率. 然而关于二氢青蒿酸与单线态氧反应的重要动力学信息并未有报道. 本文通过光敏化法产生单线态氧，研究二氢青蒿酸与单线态氧之间的反应速率常数. 通过直接检测单线态氧在1270 nm处的发光衰减动力学，得出单线态氧与二氢青蒿酸在不同溶剂中的反应速率常数分别为：在CCl₄中为1.81×10⁵ (mol/L)^-1·s^-1，在CH₃CN中为5.69×10⁵ (mol/L)^-1·s^-1，DMSO中为3.27×10⁶ (mol/L)^-1·s^-1. 发现在三种溶剂中二氢青蒿酸与单线态氧的反应速率常数随着溶剂极性的增加而增加. 这些结果为优化青蒿素光化学合成的实验条件提供了基础知识，有助于提高青蒿素的合成效率.     

电子通量对ZnO/K2SiO3热控涂层光学性能的影响

 研究了电子通量对ZnO/K₂SiO₃热控涂层光学性能的影响。分别采用通量为5×10¹¹/cm²·s，8×10¹¹/cm²·s，1×10¹²/cm²·s 和5×10¹²/cm²·s的电子对试样进行辐照。电子辐照下涂层的光学性能发生了退化，并且发现了退化涂层在空气中的“漂白”现象。分析了ZnO/K₂SiO₃热控涂层光学性能的退化机制，同时讨论了电子通量对太阳光谱吸收系数的影响。实验结果发现，在5×10¹¹～1×10¹²/cm²·s的电子通量范围内，电子通量对ZnO/K₂SiO³热控涂层光学性能的影响相同。因此在这个电子通量范围内，采用加速地面试验来模拟空间的电子辐照效应是有效的。     

Cl/HN3/I2全气相化学激光体系的化学动力学模拟计算

 对Cl/HN₃/I₂产生NCl(a)/I激光的过程进行了化学动力学计算，主要考察了Cl,HN₃和I₂的初始粒子数密度及其配比对小信号增益系数的影响。结果发现,当温度为400K, 初始Cl粒子数密度为1×10¹⁵，1×10¹⁶和1×10¹⁷cm^-3时,小信号增益系数分别达到1.6×10^-4,1.1×10^-3和1.1×10^-2cm^-1，获得最佳小信号增益系数的HN₃和I₂的初始粒子数密度分别为初始Cl粒子数密度的1～2倍和2%～4%。同时，对Cl，HN₃和I₂配比对小信号增益系数和增益持续时间的影响进行了讨论。     

乙腈-水和乙二醇-水均相溶液中光诱导杜醌激发三重态与色氨酸、酪氨酸的氢原子转移反应

本文用激光闪光光解技术研究了光诱导生物醌杜醌激发三重态(³DQ^*)和色氨酸(Trp)与酪氨酸(Tyr)在乙腈-水(MeCN-H₂O)及乙二醇-水(EG-H₂O)均相溶液中的光化学反应,分析了反应的机理,并基于Stern-Volmer方法测量了反应速率常数. 光解DQ体系可以生成³DQ^*,³DQ^*与Trp、Tyr发生的氢原子转移反应占主导地位. 对于DQ/Trp/MeCN-H₂O和DQ/Trp/EG-H₂O溶液,³DQ^*与Trp反应生成杜醌中性自由基DQH^·、以碳为中心的色氨酸中性自由基Trp^·/NH和以氮为中心的色氨酸中性自由基Trp/N^·. 对于DQ/Tyr/MeCN-H₂O和DQ/Tyr/EG-H₂O溶液,³DQ^*与Tyr反应生成DQH^·和酪氨酸中性自由基Tyr/O^·. ³DQ^*与Trp、Tyr的氢原子转移反应速率常数都在10⁹ L·mol^-1·s^-1量级,反应近似受扩散控制. MeCN/H₂O均相溶液中³DQ^*与Trp、Tyr的反应速率常数要明显高于EG/H₂O均相溶液中的反应速率常数,这与Stokes-Einstein方程定性一致.     

粲夸克偶素P波态χc0宽度测量

利用北京谱仪在北京正负电子对撞机上采集的350万(2S)事例,通过ψ(2S)→γπ⁺π^－和γK⁺K^－反应道测量了χ_c0的总宽度.由Monte Carlo模拟给出的质量分辨函数,利用拟合χ_c2谱形得到的质量分辨作标定后,用于χ_c0宽度的拟合,得到χ_c0的宽度为(15.0)MeV.同时定出了χ_cJ(J=0,2)到π⁺π^－+K^－的衰变分支比.结果为B(χ_c0→π⁺π^－)=(4.27±0.23±0.60)×10^－3,B(χ_c0→K⁺K^－)=(3.44±0.21±0.47)×10^－3,B(χ_c2→π⁺π^－)=(1.52±0.17±0.29)×10^－3 和 B(χ_c2→K⁺K^－)=(5.2±1.1±1.8)×10^－4,其中第一项误差为统计误差,第二项为系统误差.     

188TL的πh9/2×υi13/2扁椭球转动带的旋称反转研究

利用能量为170MeV的³⁵Cl束流, 通过¹⁵⁷Gd(³⁵Cl,4n)熔合蒸发反应研究了¹⁸⁸Tl的 高自旋态能级结构. 依据实验结果建立了¹⁸⁸Tl基于πh_9/2×υi_13/2组态的转动带. 根据双奇Tl核能级结构的相似性, 指定了¹⁸⁸Tlπh_9/2×υi_13/2扁椭球转动带的自旋值. 结果表明在¹⁸⁸Tl中, πh_9/2×υi_13/2扁椭球转动带在低自旋区具有旋称反转性质. 利用包含了质子-中子剩余相互作用的准粒子-转子模型, 定性地解释了πh_9/2×υi_13/2扁椭球转动带的低自旋区旋称反转现象.     

Ferroelectric and optical properties of Ba6Ti2Nb8O30 single crystals

The dielectric, optical and non-linear optical properties of Ba₆Ti₂Nb₈O₃₀ single crystals were examined from room temperature up to the Curie temperature of 245°C. The spontaneous polarization at room temperature was estimated as 0·22±0·01 C/m². The linear electrooptic constants were measured as r₃₃^T=(1·17±0·02)×10^?10 and r₁₃^T=(0·42±0·01)×10^?10 m/V. The non-linear optical coefficients were d₃₃=(15·1±2·0)×10^?12 and d₃₁=(11·0±2·0)×10^?12 m/V, which are comparable to those of Ba₄Na₂Nb₁₀O₃₀. Temperature dependences of δ₃₃ and δ₃₁ (Miller's δ) were found to be proportional to that of P_s.     

Vibrationally unrelaxed fluorescence in matrix isolated CF2

The CF₂ emission spectrum in rare gas solids involves both the symmetric vibrations, ν₂ (668 cm^?1) and ν₁ (1120 cm^?1). A vibrationally unrelaxed emission is observed following selective excitation of the higher vibrational levels in the ν₂ manifold, and we measure vibrational relaxation rates of 2 × 10⁸/sec and 1.1 × 10⁸/sec, respectively, for the 2-1 and 1-0 relaxation in argon. All the vibrational bands show a strong coupling to the lattice modes, with a weak ZPL and strong phonon wing. This results from the change in geometry between the ground and excited electronic states.     

Phonon coupled cooperative low-spin 1A1high-spin 5T2 transition in [Fe(phen)2(NCS)2] and [Fe(phen)2(NCSe)2] crystals

Heat capacities of [Fe(phen)₂(NCS)₂] and [Fe(phen)₂(NCSe)₂] were measured between 13⁵ and 375 K. A heat capacity anomaly due to the spin-transition from low-spin ¹A₁ to high-spin π₂ electronic ground state was found at 176·29 K for the SCN-compound and at 231·26 K for the SeCN-compound, respectively. Enthalpy and entropy of transition were determined to be ΔH = 8·60 ± 0·14 kJ mol^?1 and ΔS = 48·78 ± 0·71 J K^?1 mol^?1 for the SCN-compound and ΔH = 11·60 ± 0·44 kJ mol^?1 and ΔS = 51·22 ± 2·33 J K^?1 mol^?1 for the SeCN-compound. To account for much larger value of ΔS compared with the magnetic contribution, we suggest that there is significant coupling between electronic state and phonon system. We also present a phenomenological theory based on heterophase fluctuation. Gross aspects of magnetic, spectroscopic, and thermal behaviors were satisfactorily accounted for by this model. To examine closely the transition process, infrared spectra were recorded as a function of temperature in the range 4000 ? 30 cm^?1. The spectra revealed clearly the coexistence of the ¹A₁, and the ⁵T₂ ground states around T_c.     

Coherent Stokes and anti-Stokes Raman spectra of the ν1 (A1) and ν2 (E) bands of SF6 and UF6

Coherent Stokes and anti-Stokes Raman scattering are used to study the ν₁ and ν₂ spectral band profiles of UF₆ and SF₆. Most of the observed SF₆ “hot” bands are assigned, leading to evaluations of the anharmonicity constants X_ij: X₁₂ = ?(2.80 ± 0.30) cm^?1, X₁₄ = ?(1.00 ± 0.15) cm^?1, X₁₅ = ?(1.00 ± 0.15) cm^?1. For UF₆, a tentative assignment of the “hot” bands is made: X₁₂ = ?(1.80 ± 0.30) cm^?1, X₁₃ = ?(1.60 ± 0.30) cm^?1, X₁₄ = ?(0.20 ± 0.10) cm^?1, X₁₅ = ?(0.25 ± 0.10) cm^?1, and X₁₆ = ?(0.10 ± 0.05) cm^?1. Parameters such as the vibration-rotation coupling constants are determined. For SF₆: α = (7 ± 2) × 10^?5 cm^?1 for the ν₂ band and α = ?(1.02 ± 0.01) 10^?4 cm^?1 for the ν₁ band. The calculated spectral profiles of the coherent Stokes or anti-Stokes spectra, which are in good agreement with experimental results, give values for the resonant and nonresonant parts of the susceptibility in both molecules. They also show, in some cases, the influence of neighboring combination bands.     

Gas‐phase oxidation of CH2 = C(CH3)CH2Cl initiated by OH radicals and Cl atoms: kinetics and fate of the alcoxy radical formed

Relative kinetics of the reactions of OH radicals and Cl atoms with 3‐chloro‐2‐methyl‐1‐propene has been studied for the first time at 298 K and 1 atm by GC‐FID. Rate coefficients are found to be (in cm³ molecule^?1 s^?1): k₁ (OH + CH₂ = C(CH₃)CH₂Cl) = (3.23 ± 0.35) × 10^?11, k₂ (Cl + CH₂ = C(CH₃)CH₂Cl) = (2.10 ± 0.78) × 10^?10 with uncertainties representing ± 2σ. Product identification under atmospheric conditions was performed by solid phase microextraction/GC‐MS for OH reaction. Chloropropanone was identified as the main degradation product in accordance with the decomposition of the 1,2‐hydroxy alcoxy radical formed. Additionally, reactivity trends and atmospheric implications are discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

Specific heat of NaNO2 near its transition points

Using an a.c. technique, the specific heat of NaNO₂ was measured as a function of temperature near its antiferroelectric-to-paraelectric phase transition point (T_N). The transition was found to be of the second order. The critical exponents are; α = 0·38 for ? = 2 × 10^?4 ～ 1 × 10^?1, and α′ = 0·18 for ? = ?2 × 10^?4 ～ ?3 × 10^?3. The critical exponents deduced from the scaling-law relations are roughly close to the values obtained from a random phase approximation for a system with an isotropic interaction. However, a difference was recognized between the observed exponent for the specific heat and the values theoretically given for T > T_N by the random phase approximation for a system with a short-range interaction or for a system with a long-range dipolar interaction. A thermodynamical analysis was made by using the generalized Pippard relation, and the present result was found to be consistent with the pressure dependence of the antiferroelectric transition point.     

332—362nm范围内CF2Cl自由基的共振增强多光子电离研究

用CF₂Cl₂分子直流脉冲放电的方法产生CF₂Cl自由基，结合共振增强多光子电离(REMPI)技术，测量了332—362nm波长范围内CF₂Cl自由基的(2+1)REMPI光谱，分析并标识了4s Rydberg态带源位于(ν_0—0=55371cm^-1)，两个被激活振动模ω′₃(CF₂剪式振动模)和ω₄′(OPL 关键词：     

Li2Mo2O6多晶材料的结构与电性能的研究

本文用固相反应烧结制备出Li₂Mo₂O₆多晶材料。经X射线分析、红外光谱和电子顺磁共振谱(EPR)的研究,确定了它的结构是Li₂Mo₂O₄和MoO₂两个晶相组成的烧结体。钼离子以四价状态存在于MoO₂晶相结构中。采用交流阻抗谱分析了晶界与温度变化的相关性。测得了样品的ln(σ_总T)-1/T 曲线是由两段直线和一段曲线所组成;总电导率化能σ_27℃=1.36×10^-3(Ω·cm)^-1,σ_115℃=1.49×10^-3(Ω·cm)^-1,σ_300℃=9.71×10^-3(Ω·cm)^-1,σ_370℃=2.42×10^-3(Ω·cm)^-1;电导活化能E₁=0.043eV,E₂=0.235eV,E_平均=0.76eV。采用维格纳极化电池法测得电子电导率σ_e,σ_e27℃=2.240×10^-5(Ω·cm)^-1,σ_e300℃=4.476×10^-3(Ω·cm)^-1。实验证明,室温下材料为固体电解质,300℃附近为良好的离子与电子混合导体。 关键词：     

Thermal decomposition and electrical conductivity of M(OH)3 and MOOH (M=Y, lanthanide)

The thermal decomposition of M(OH)₃ (M=Y, La, Nd, Sm, Gd) with the Y(OH)₃ structure was examined by the TG and DTA methods. Y(OH)₃, Nd(OH)₃, and Sm(OH)₃ decomposed to MOOH and then to M₂O₃. The decomposition of La(OH)₃ and Gd(OH)₃ occurred via the following schemes: La(OH)₃→LaOOH→La₂O₃·1/2H₂O→La₂O₃, and Gd(OH)₃→Gd₂O₃·3/2H₂O→GdOOH→Gd₂O₃. The highest conductivity of 5.9×1o^?9Scm^?1 at 250°C was found in Gd(OH)₃ and that of 8.9×10^?7 S cm^?1 400°C in GdOOH. The continuous-wave ¹H NMR absorption spectrum of LaOOH at room temperature exhibited no doublet line shape. This shows that protons are magnetically isolated from each other, and very little H₂O and H₃O⁺ can exist.