A high sensitivity titration calorimeter using pyroelectric sensor

A new sensitive isothermal titration microcalorimeter using polyvinylidene difluoride (PVDF) as detector has been developed. Heat pulses of less than 0.4 μJ can be detected and the baseline noise level (p-p) is 40 nW. The calorimeter is constructed with one reaction cell (0.7 ml) insulated by several radiation shields inside a vacuum chamber. The performance of the instrument was examined by measuring the heat of protonation of Tris with HCl. The enthalpy of reaction was found to be ?49±1 kJ·mol^?1, in good agreement with the reported value of ?47.5 kJ·mol^?1.     

用最小电离的质子刻度铅–闪烁光纤夹层电磁量能器

研究利用最小电离的质子和已知能量的电子来刻度铅–闪烁光纤夹层电磁量能器.对最小电离粒子输出响应进行光纤衰减修正后,利用最小电离质子的输出响应对量能器测量单元进行标定,然后对不同入射能量的电子事例进行能量重建,重建能量与入射能量有很好的线性关系.本文还对最小电离的质子与μ子对量能器测量单元的输出响应进行了比较,发现二者在误差范围内是一致的.     

60keV质子辐照对TiNi记忆合金薄膜马氏体相变的影响

 利用磁控溅射的方法在氧化后的单晶Si基片上制备了TiNi形状记忆合金薄膜，利用示差扫描量热法和原位X射线衍射研究了薄膜的马氏体相变特征。通过60keV质子注入（辐照）薄膜样品研究了H+离子对合金薄膜马氏体相变特征的影响，结果表明氢离子注入后引起了马氏体相变开始Ms和结束点Mf以及逆马氏体相变开始As和结束温度Af的下降，而对R相变开始Rs和结束温度Rf影响不大。掠入射X射线衍射表明H+离子注入后有氢化物形成。H⁺离子注入形成的氢化物是引起相变点的变化的主要因素。     

Creation of entangled states of excitons in coupled quantum dots

We present two methods for the creation of two-particle entangled states of excitons in a coupled quantum dot system. The system contains two identical quantum dots that are coupled by an inter-dot hopping process. The manipulation of the system is succeeded by proper application of an external laser field.     

Direct measurement of the magnetocaloric effect in La0.67Ca0.33MnO3

Polycrystalline perovskite La_0.67Ca_0.33MnO₃ was synthesized by a sol–gel method. Its adiabatic temperature change ΔT_ad induced by a magnetic field change was measured directly. At 268 K, near its Curie temperature T_C, ΔT_ad of La_0.67Ca_0.33MnO₃ induced by a magnetic field change of 2.02 T reaches 2.4 K. The latent heat Q and magnetic entropy change −ΔS_M induced by a magnetic field change were calculated from the temperature dependence of ΔT_ad and zero-field heat capacity C_p. The maximum values of Q and −ΔS_M in La_0.67Ca_0.33MnO₃ induced by a magnetic field change of 2.02 T are 1.85 J g⁻¹ and 6.9 J kg⁻¹ K⁻¹, respectively. The former is larger than the phase transition latent heat of heating or cooling, which is about 1.70 J g⁻¹.     

配合物Zn(Phe)(NO3)2·H2O(s)的低温热容和标准摩尔生成焓

利用精密自动绝热热量计直接测定了配合物Zn(Phe)(NO3)2·H2O(s) (Phe:苯丙氨酸)在78-370 K温区的摩尔热容. 通过热容曲线的解析得到该配合物的起始脱水温度为, T0=(324.27±0.37) K. 将该温区的摩尔热容实验值用最小二乘法拟合得到摩尔热容(Cp, m)对温度(T)的多项式方程, 并且在此基础上计算出了它的舒平热容值和各种热力学函数值. 依据Hess定律, 通过设计热化学循环, 选择体积为100 mL浓度为2 mol·L-1 的盐酸作为量热溶剂, 利用等温环境溶解-反应热量计分别测定混合物{ZnSO4·7H2O(s)+2NaNO3(s)+L-Phe(s)}和{Zn(Phe)(NO3)2·H2O(s)+Na2SO4(s)}的溶解焓为, ⊿dH0m,1 =(69.42±0.05) kJ·mol-1, ⊿dH0 m,2 =(48.14±0.04) kJ·mol-1, 进而计算出该配合物的标准摩尔生成焓为, ⊿fH0m =-(1363.10±3.52) kJ·mol-1. 另外, 利用紫外-可见(UV-Vis)光谱和折光指数(refractiveindex)的测量结果检验了所设计的热化学循环的可靠性.     

SSCH3光解离的多参考理论计算

摘要运用多参考微扰理论(Multireference MΦller-Plesset theory)计算了SSCH3垂直激发能及其S-C与S-S两种断键方式的绝热(Adiabatic)与非绝热(Diabatic)的基态和激发态势能曲线, 研究了在193nm激光作用下SSCH3的光解离过程, 理论计算值与实验值相符.     

水-乙醇二元体系共沸混合物的热力学研究

用全自动低温绝热量热计测定了水、乙醇以及水和乙醇组成的共沸混合物在不同温区的摩尔热容Cp,m. 建立了共沸混合物Cp,m与温度T的函数关系.结果表明,水和乙醇组成的共沸混合物在98.496 K发生玻璃态转化,在158.939 K 和270.95 K发生固-液相变.获得了其相应的相变焓和相变熵.计算了以298.15 K为基准的该共沸混合物的热力学函数和超额热力学函数.     

Assignment of the first photoelectron band of the CH<Subscript>3</Subscript>CHCl radical using ab initio quantum mechanical calculations

HeI photoelectron spectra have been recorded for the reaction of atomic fluorine with ethyl chloride at different reaction times. A structured band associated with a short-lived primary reaction product has been recorded with adiabatic and vertical ionization energies of (7.84±0.02) and (8.18±0.02) eV respectively. An average vibrational separation of (680±30) cm^–1was observed in this band. Comparison between the experimental vertical and adiabatic ionization energies and ionization energies computed for CH₃CHCl (X²A) and CH₂CH₂Cl (X²A) at different levels of theory led to the assignment of the observed first photoelectron band to the ionization of CH₃CHCl (X²A). The observed vibrational structure was assigned to excitation of the C–Cl stretching mode in CH₃CHCl⁺(X¹A).Proceedings of the 11th International Congress of Quantum Chemistry satellite meeting in honor of Jean-Louis Rivail     

Thermodynamic studies of monuron

Monuron (C₉H₁₁ClN₂O; N,N-dimethyl-N′-(4-chlorophenyl) urea, CAS 150-68-5) was synthesized and the heat capacities of the compound were measured in the temperature range from 79 to 385 K with a high precision automated adiabatic calorimeter. No phase transition or thermal anomaly was observed in this range. The enthalpy and entropy data of the compound relative to the reference temperature 298.15 K were derived based on the heat capacity data. The thermodynamic properties of the compound were further investigated through DSC and TG analysis. The melting point, the molar enthalpy, and entropy of fusion were determined to be 447.6±0.1 K, 29.3±0.2 kJ mol⁻¹, and 65.4 J K⁻¹ mol⁻¹, respectively.