甲基卤化物的脱卤研究以及在盐溶液(NaCl)环境中通过紫外光分解CH_2I_2制备强酸(英文)

pacc:8240,8250F TheultravioletphotolysisofCH2I2wasstud iedinwater[1-3]andsaltwatersolutionsusing photochemistryandpicosecondtime-resolved resonanceRamanspectroscopy.Photolysisinboth typesenvironmentsproducesmainlyCH2(OH)2andHIproducts.However,photolysisof…     

显微激光拉曼定量分析CO_2气体碳同位素组成方法研究

制备了一系列不同比例的~(12)CO_2/N_2和~(13)CO_2/N_2混合物,对样品进行显微激光拉曼测试分析后发现气体拉曼特征峰峰面积比与其摩尔分数比成正比例关系,拟合方程的斜率被认为是拉曼量化因子F_(12CO_2)和F_(13CO_2)。用气相组分中只含有~(12)CO_2和N_2的流体包裹体验证了当F_(12CO_2),为1.163 49时,根据气体的拉曼特征峰峰面积比能估算出其摩尔分数比。由线性拟合后的方程斜率得出F_(13CO_2)和F_(12CO_2)分别为1.610 86和1.163 49,它们的比率F_(13CO_2)/F_(12CO_2)是1.3845。在确定稳定同位素分子的拉曼参数和实验条件基础上,CO_2气体碳同位素摩尔分数比C_(12)/C_(13)可根据A_(12Co_2)/A_(13CO_2)(拉曼峰峰面积比)和F_(13CO_2)/F_(12CO_2)的乘积求出。此外,用已知摩尔分数比(C_(12)/C_(13))的人造包裹体验证了此方法具有一定的可行性,可以建立起定量分析CO_2气体碳同位素激光拉曼测试方法。     

SiO2半波覆盖层对HfO2／SiO2高反射膜激光损伤的影响

研究了SiO2半波覆盖层对HfO2／SiO2高反射膜1064nm激光损伤的影响,分析薄膜的激光损伤特性及图貌得出-对于单脉冲(1-ON-1)激光损伤,SiO2半波覆盖层能提高HfO2／SiO2高反射膜的激光损伤厨值,可显著降低激光损伤程度,减小灾难性损伤发生的概率,可大幅度提高FIfO2／SiO2高反射膜的抗激光损伤能力。     

Ultrasonic relaxation study of preferential solvation in quasi-two-components aqueous solutions of amides and zinc salts

To investigate the effect of preferential solvation the ultrasonic attenuation (2-50 MHz) and velocities (3 MHz) of ZnCl(2) and 2-chloroacetamide (ClCH(2)CONH(2)) in water and its quasi-binary mixtures with the ratio (ZnCl(2)+ClCH(2)CONH(2)):H(2)O=1:55 at 298.15 K have been measured. The creation of specific complexes in the ClCH(2)CONH(2)-H(2)O-ZnCl(2) system have a relaxational character which, within the measurements of ultrasonic absorption in the frequency range 2-50 MHz, have been observed. On the base of these properties the kinetic and dynamic parameters of the observed relaxation have been calculated. To bring into relief the influence of Cl atom in the 2-chloroacetamide molecules for complexation process it has been investigated also the system AA-H(2)O-ZnCl(2). The next step of searching was to investigate the system of CHAA-H(2)O-ZnBr(2), to reduce the influence of Cl atom within ZnCl(2) molecule at the complexation process. The main aim of presented study was to investigate the possibility of complexation in the aqueous solutions of ZnCl(2) with the part of 2-ClCH(2)CONH(2) (CHAA). With regard of big complexing ability of zinc, there exist a theoretical possibility of attachment CHAA to the inner coordination sphere of zinc through chloride atom. There can create here outer-sphere as well as inner-sphere complexes. As a results the observed relaxation processes have been attributed to creation and disintegration the following complexes: Zn(H(2)O)(2)(CHAA)(4)(2+) and Zn(2+)(H(2)O)(3)(CHAA)Cl(2)(-).     

H2AT120 蛋白磷酸化致癌的动力学特性

基于Hill动力学与Michaelis-Menten方程,建立理论模型研究H2AT120组蛋白磷酸化促进癌症发生发展的动力学特性.研究发现,在H2AubK119-H2AT120D-H2AT120P信号通路中,VRK激酶(vaccinia-related kinase 1)在很大程度上调控H2AT120磷酸化的动力学. VRK过高或者过低表达,都会促使H2AT120磷酸化出现异常,导致基因的不恰当表达,致使细胞癌变发生.通过考察体系演化过程中的动力学稳定性,我们发现,H2AubK119、H2AT120D、H2AT120P随时间演化动力学出现Hopf分岔,表明了体系随时间演化动力学的转变特性,由此也表明了,H2AT120蛋白磷酸化促进癌症发生发展的复杂性.基于本文模型,我们解释了VRK、H2AubK119、H2AT120D对致癌的调控特性,进一步理解了H2AubK119-H2AT120D-H2AT120P信号回路的致癌作用机理.理论结果符合实验,揭示了H2AT120磷酸化导致表观遗传变异的一种致癌机理,可为设计阻止由H2AT120发生变异诱发的癌症提供理论依据.     

阳离子对硅酸盐玻璃激光拉曼光谱影响的研究

运用拉曼光谱技术研究了Na2O(K2O)—CaO(MgO)—SiO2,Na2O(K2O)—Al2O3—SiO2,Na2O(K2O)—B2O3—SiO2,Na2O(K2O)—PbO—SiO2和PbO—BaO—SiO2五个系统的玻璃。结果表明,阳离子对玻璃近程结构的改造会引起拉曼特征的变化。部分样品是根据古玻璃平均成分在实验室烧制的,这项研究对于运用激光拉曼光谱区分不同系统的古代硅酸盐玻璃有重要意义。     

Dependence of the selectivity of SnO2 nanorod gas sensors on functionalization materials

Effects of functionalization materials on the selectivity of SnO₂ nanorod gas sensors were examined by comparing the responses of SnO₂ one-dimensional nanostructures functionalized with CuO and Pd to ethanol and H₂S gases. The response of pristine SnO₂ nanorods to 500 ppm ethanol was similar to 100 ppm H₂S. CuO-functionalized SnO₂ nanorods showed a slightly stronger response to 100 ppm H₂S than to 500 ppm ethanol. In contrast, Pd-functionalized SnO₂ nanorods showed a considerably stronger response to 500 ppm ethanol than to 100 ppm H₂S. In other words, the H₂S selectivity of SnO₂ nanorods over ethanol is enhanced by functionalization with CuO, whereas the ethanol selectivity of SnO₂ nanorods over H₂S is enhanced by functionalization with Pd. This result shows that the selectivity of SnO₂ nanorods depends strongly on the functionalization material. The ethanol and H₂S gas sensing mechanisms of CuO- and Pd-functionalized SnO₂ nanorods are also discussed.     

Fractionation of hydrogen isotopes between crystalline hydrates and saturated solution of cobalt dichloride

The hydrogen isotopic fractionation factors between the crystal water (CW) in crystalline hydrates and the saturated aqueous solution of cobalt dichloride, alphaCW-st.sol, were experimentally determined in the temperature range from 10 to 55 degrees C under equilibrium condition: alphaCW-st.sol in cobalt dichloride hexahydrate, CoCl2 x 6H2O, from 10 to 43 degrees C, and in cobalt dichloride dihydrate, CoCl2 x 2H2O, at 50 and 55 degrees C. The empirical relationship between ln alphaC.W.-st.sol and (1/T2) on the CW of CoCl2 x 6H2O in the temperature range from 10 to 43 degrees C was obtained as: 10(3)ln alphaCW-st.sol=-2.46(10(6)/T2)+17.6. The CW of dihydrate of cobalt dichloride exhibits larger depletion of deuterium than that of hexahydrate. The values of alphaCW-st.sol in CoCl2 x 2H2O are similar to that of CuCl2 x 2H2O and BaCl2 x 2H2O at 25 degrees C. This fact indicates that the hydrogen fractionation factor between the CW and the saturated aqueous solution of cobalt dichloride strongly depends on the structure of crystalline hydrate rather than the chemical species of cation and/or the crystallized temperature.     

2,6-二氨基吡啶衍生物作为过渡金属离子荧光探针的研究

2,6-二氨基吡啶(DAPD)衍生物都有较强的荧光。除DMHND(2,4-二甲基-7-羟基-1,8-萘啶)外,2,4-二甲基-7-胺基-1,8-萘啶(DMAND)和2,4-二甲基-7-丙烯酰胺基-1,8-萘啶(DMAAN)在加入过渡金属离子后,荧光强度增强,发射光谱红移,可以作为过渡金属离子的荧光探针。根据Irving-Williams顺序,以过渡金属中络合能力较强的Cu2+为代表,求算了DMAND和DMAAN与Cu2+的结合比,通过非线性拟合计算了结合常数,比较了它们与金属离子结合的强弱,DMAND较DMAAN为更灵敏的过渡金属离子荧光探针。     

电荷调控下Ti3C2O2和V2CO2吸附CH4的第一性原理计算

本文采用第一性原理计算首先研究了Ti3C2O2和V2CO2与CH4气体分子之间的相互作用,发现Ti3C2O2和V2CO2对CH4的吸附较弱属于物理吸附,不适宜用作探测CH4。在此基础上研究了电荷调控下CH4气体分子与Ti3C2O2和V2CO2之间的相互作用。结果表明：随着体系电荷态的增加,Ti3C2O2和V2CO2对CH4气体分子的吸附作用逐渐增加变为化学吸附。当体系电荷态大于或等于-2时,CH4气体分子在Ti3C2O2和V2CO2表面可以被有效捕获。撤去电荷后,Ti3C2O2、V2CO2与CH4气体分子之间的吸附恢复至物理吸附,CH4气体分子易脱附。因此,通过调控Ti3C2O2和V2CO2的电荷态,可以简单地实现CH4的捕获与释放。Ti3C2O2和V2CO2有望成为CH4探测或捕获材料。     

汞在Ti2NO2 MXene表面吸附氧化的第一性原理计算

汞是一种有毒的重金属,在生产生活中以各种形式排放的汞对生态及人类健康都存在一定程度的威胁.因此,寻找高效的汞吸附剂具有十分重要的意义.本文基于密度泛函理论的第一性原理计算方法,研究了汞在Ti₂NO₂(MXene)和具有一个氧空位缺陷的Ti₂NO₂(Ov-Ti₂NO₂)上的吸附和氧化机理.计算结果表明Hg⁰在Ti₂NO₂表面的吸附为物理吸附,在Ov-Ti₂NO₂表面为化学吸附. Ti₂NO₂表面氧空位的存在可以改善HgO与Ov-Ti₂NO₂之间的相互作用,从而使吸附能提高116 kJ/mol. Hg⁰在Ov-Ti₂NO₂表面氧化为HgO的反应能垒为92.55 kJ/mol,小于其在Ti_2<...     

Photoexcitation of K-shell and L-shell hollow beryllium

We have observed K-shell and L-shell hollow beryllium atoms (2s(2)2p3s and 1s3s(2)3p) created by photoexcitation using synchrotron radiation. Resonance shapes were fitted to the Fano profile and the parameters were deduced. A Dirac-Fock calculation was performed to identify the configuration of the peaks and to predict other hollow atomic peaks. The results of the calculation were in good agreement with the experimental data. The comparison of the transition strength has revealed that the three-electron photoexcitation to the 1s3s(2)3p configuration is stronger than the two-electron photoexcitation to the 2s(2)2p3s configuration. This is attributed to the large overlap between the 2s orbital of the ground state (1s(2)2s(2)) with the orbital of the L-shell hollow state (1s3s(2)3p).     

Cs 39D态Rydberg原子Stark光谱的实验研究

本文从理论和实验上对Cs39D态Rydberg原子在弱电场作用下的Stark效应做了详细研究. 理论上利用数值方法计算了Cs原子39D态的Stark结构;实验上,采用两步激发超冷基态原子获得超冷Rydberg原子,通过场电离的方法获得了39D态的Stark光谱,测量获得α^5/2₂,α^5/2₀,α^3/2₂和α^3/2₀相应的极化率分别为：62(7),－146(13), 73(6) 和－106(20) MHz·V^-2cm²,实验结果与理论相符合. 关键词： Rydberg原子 Stark结构 场电离 极化率     

Ultrasonically initiated emulsion polymerization of styrene in the presence of Fe2+

Ultrasonically initiated emulsion polymerization of styrene was carried out in the presence of Fe(2+). The addition of a small amount of Fe(2+) markedly enhanced the polymerization rate of styrene. In the presence of 50 microM Fe(2+), the conversion of monomer in the reaction time of 60 min was 2.4 times as high as that in the absence of Fe(2+). The increase in the polymerization rate was due to higher concentration of hydroxyl (*OH) radicals generated via Fenton reaction of Fe(2+) with hydrogen peroxide (H(2)O(2)), which was proved by a lower amount of H(2)O(2) in Fe(2+) aqueous solution compared with that in pure water during ultrasonic irradiation. However, the addition of excessive Fe(2+) had no further accelerating effect on the polymerization rate due to the reduction of *OH radicals by Fe(2+). So it is an effective way to add an appropriate amount of Fe(2+) to accelerate ultrasonically initiated emulsion polymerization of styrene.     

Optical properties of two-dimensional perovskites

The optical properties of two-dimensional (2D) perovskites recently receive numerous research focus thanks to the strong quantum and dielectric confinement effects. In addition to the strong excitonic effect at room temperature, 2D perovskites also have appealing features that their optical properties can be flexibly tuned by alternating organic or inorganic layers. Particularly, 2D chiral perovskites and 2D perovskites based heterostructures are emerging as new platforms to extend their functionalities. To optimize performance of 2D perovskites-based optoelectronic devices, it is critical to understand the fundamentals and explore the strategies to engineer their optical properties. This review begins with an introduction to the excitons and self-trapped excitons of 2D perovskites. Subsequently, inorganic/organic layer effects on optical properties and 2D perovskites based heterostructures are discussed. We also discussed the nonlinear optical properties of 2D perovskite. We are looking forward to that this review can stimulate more efforts to understand and optimize the optical properties of 2D perovskites.     

锌盐与二甲氧基嘧啶配合物的光谱研究

无水乙醇中回流制得ZnCl_2和ZnSO_4与2-氨基-4,6-二甲氧基嘧啶(AMP)的1:2和1:1固态配合物,用化学分析和元素分析确定它们的组成分别为Zn(AMP)_2Cl_2(A)和Zn(AMP)SO_4(B);用IR,XPS和~1HNMR研究了它们的成键情况。IR光谱分析说明配合物中,配体通过氨基N原子及嘧啶环上一个N原子与Zn~(2 )双齿配位,配合物B中SO_4~(2-)参与了配位;XPS谱证明配合物A中和B中SO_4~(2-)均参与了配位,并且N→Zn~(2 )键中有不同程度的反馈键;~1H NMR说明配合物A中有2个配体参与配位,配合物B中只有1个配体参与了配位。由此推测了它们的可能结构。     

Isotope-selective IR multiphoton dissociation of CHClF2 in the presence of NO2

2 to the CHClF₂/He mixture irradiated by a Q-switched CO₂ laser leads to oxidation of the dissociation product according to the reaction: CF₂+NO₂→COF₂+NO. The resulting COF₂ with a ¹³C content near 50% is easy to convert to CO₂ or CO for further enrichment by a nonlaser process. We measured the dependence of the fraction of dimerised CF₂ on NO₂ pressure p_NO2 and the amount of NO₂ required to suppress dimerisation on the dissociation yield. Both agree with a kinetic model using known rate constants. For the range of the dissociation parameters (¹³CF₂ yield of 10% per pulse, isotope selectivity of 130) of practical interest, 95% of the CF₂ produced is oxidized at p_NO2≈1/2p_CHClF2. In the absence of NO₂, major (20%–35%) losses of CF₂ at the metal walls of the irradiation system were observed. Addition of NO₂ suppresses them. For comparison, we also used O₂ as a scavenger in CHClF₂ dissociation. NO₂ is by orders of magnitude more efficient. Received: 21 January 1997/Revised version: 23 March 1997     

常见氯盐溶液中阳离子对水分子氢键影响的拉曼光谱研究

为了全面认识地质流体中常见阳离子对水的结构的影响, 在室温下通过对NaCl—H₂O,CaCl₂—H₂O,MgCl₂—H₂O,CuCl₂—H₂O,ZnCl₂—H₂O和FeCl₃—H₂O体系中水的O—H伸缩振动拉曼谱3 400 cm-1左右的最大峰频率的移动和低于3 433 cm-1强肩峰强弱的系统研究,考察了常见阳离子的离子电荷、离子半径、离子所属族以及络合效应等因素对水的O—H伸缩振动拉曼光谱的影响。并首次通过络合物的生成和阳离子破坏效应的共同作用来讨论相同浓度的不同种类氯盐溶液中阳离子对水氢键的影响,得到结论,对水的氢键的破坏作用：CaCl₂＞MgCl₂＞FeCl₃＞NaCl＞ZnCl2＞CuCl₂。     

XPS analysis of the oxidation reaction of ruthenium-chalcogenide photoelectrodes

The oxidation of RuS₂, RuSe₂, and RuTe₂ single crystals and polycrystalline samples by air and electrochemical / photoelectrochemical means have been studied by XPS. The amount of oxidized species detected at the surface can be related to the tendency of the material to electrochemical corrosion. For RuS₂, which is able to oxidize H₂O to O₂ only an oxidation of the top surface layer can be derived from the changes of the O1s is signal. For RuSe₂ and RuTe₂ Ru-oxide/hydroxide and chalcogenide-oxide species are detected in correspondence to their corrosion tendency. The results of the XPS analysis are discussed with respect to the electrocatalytic properties of the materials.     

偏磷酸根(PO-3)对氟铝酸盐玻璃透光性能影响

在氟铝酸盐玻璃（AMCSBY）中引入Ba(PO3）2替代BaF2,替代公式为10MgF2-20CaF2-(10-x)BaF2-10SrF2-15YF3-35AlF3-xBa(PO3)2(x=,2,4,6,8)。对玻璃进行了差热分析，结果表明，在氟铝酸盐玻璃中引入偏磷酸盐使玻璃形成能力大大提高；测量了玻璃从紫外到红外的透过光谱和紫外吸收光谱，在玻璃中引入偏磷酸钡使玻璃中红外透过能力下降，红外吸收边带移向短波段，玻璃紫外透过能力得到提高。紫外吸收边带移向紫外波段，由于PO3^-的影响，O－H吸收峰由2830nm移到3145nm。