Laser induced multi-component luminescence of [CuNCS(1,10-phen)P(CH2N(CH2CH2)2O)3]—the first example of CuNCS complexes with diimines and tris(aminomethyl)phosphanes

[CuNCS(phen)P(CH₂N(CH₂CH₂)₂O)₃], a novel mixed-ligand complex of copper(I) isothiocyanate with 1,10-phenanthroline and tris(aminomethyl)phosphane derived from morpholine have been synthesized. It was characterized by elemental analysis, thermogravimetric and differential thermal analyses and studied by NMR, mass, UV–Vis, IR and luminescence spectroscopies. The X-ray structure of the complex was determined. The coordination geometry about the Cu(I) center is pseudo-tetrahedral. The complex exhibits a very weak photoluminescence in the solid state. Surprisingly, the luminescence spectra of the crystalline sample at room and LN temperatures show several bands similarly to absorption(reflectance) spectrum. On the basis of TDDFT calculations we interpreted these bands as of MLLCT type resulting mainly from two transitions: π^?(CuNCS)→π^?(phen) and σ(CuP)→π^?(phen). This strongly suggests that all the ligands are involved into absorption and PL spectra, however their complex character (several bands observed) does not allow the more precise interpretation.     

Total cross sections of electron scattering by molecules NF3, PF3, N(CH3)3, P(CH3)3, NH(CH3)2, PH(CH3)2, NH2CH3 and PH2CH3 at 30–5000 eV

Total cross sections of electron scattering by eight molecules NF₃, PF₃, N(CH₃)₃, P(CH₃)₃, NH(CH₃)₂, PH(CH₃)₂, NH₂CH₃ and PH₂CH₃, which have some structural similarities, are calculated at the Hartree-Fork level by the modified additivity rule approach [D.H. Shi, J.F. Sun, Z.L. Zhu, H. Ma, Y.F. Liu, Eur. Phys. J. D 45, 253 (2007); D.H. Shi, J.F. Sun, Y.F. Liu, Z.L. Zhu, X.D. Yang, Chin. Opt. Lett. 4, 192 (2006)]. The modified additivity rule approach takes into considerations that the contributions of the geometric shielding effect vary as the energy of incident electrons, the dimension of target molecule, the number of electrons in the molecule and the number of atoms constituting the molecule. The present investigations cover the impact energy range from 30 to 5000 eV. The quantitative total cross sections are compared with those obtained by experiments and other theories. Excellent agreement is observed even at energies of several tens of eV. It shows that the modified additivity rule approach is applicable to carry out the total cross section calculations of electron scattering by these molecules at intermediate and high energies, in particular over the energy range above 80 eV or so. It proves that the microscopic molecular properties, such as the geometrical size of the target and the number of atoms constituting the molecule, are of crucial importance in the TCS calculations. The new results for PH(CH₃)₂ and PH₂CH₃ are also presented at energies from 30 to 5000 eV, although no experimental and theoretical data are available for comparison. In the present calculations, the atoms are still represented by the spherical complex optical potential, which is composed of static, exchange, polarization and absorption terms.     

Vibrational spectra of an LiNO3–(CH3)2SO2 system

Raman and IR absorption spectra were studied and molecular relaxation characteristics of vibrations of the anion and solvent were calculated for an xLiNO₃–(1 – x)(CH₃)₂SO₂ system (x = 0.1, 0.2, 0.3, 0.4 M). It was found that it is impossible to increase the concentration of free ions involved in charge transfer in such a system by either increasing the temperature or changing the concentration composition in the studied range of x.     

Equation of state and structural characterization of Cu4I4{PPh2(CH2CH = CH2)}4 under pressure

Combined high pressure single crystal X-ray diffraction experiments and ab initio simulations based on the density functional theory have been performed on a copper(I) iodide cluster formulated [Cu₄I₄{PPh₂(CH₂CH?=?CH₂)}₄] under high pressure up to 5?GPa. An exhaustive study of compressibility has been done by means of determination of isothermal equations of state and structural changes with pressure at 298?K taking advantage of the single crystal is more precise than powder X-ray diffraction for this type of experiments. It allows us to report the evidence of the existence of an isostructural phase transition of second order at 2.3?GPa not detected so far.     

Quantum chemical study of the (Z)-2-penten-1-ol (HOCH2–CH = CHCH2CH3) + OH + O2 reactions

ABSTRACT

The mechanism and products of the reaction of (Z)-2-penten-1-ol [(Z)-PO21] with OH radical in the presence of O₂ have been elucidated by using high-level quantum chemical methods CCSD(T)/6-311+G(d,p)//BH&;HLYP/6-311++G(d,p). The calculations clearly indicate that addition channels contribute maximum to the total reaction and H-abstraction channels can be neglected at temperatures of 220–500 K. The rate constant for the reaction of OH radical with (Z)-PO21 at 298 K is computed to be 1.22 × 10^?10 cm³ molecule^?1 s^?1, which is in stronger agreement with the previously reported experimental values. The kinetic data obtained over the temperature range 220?500 K are used to derive an non-Arrhenius expression: k = 3.69 × 10^?13 × exp(1763.7/T) cm³ molecule^?1 s^?1. For the reaction of (Z)-PO21with OH radical in the presence of O₂, the major primary reaction products found in this study are propanal [CH₃CH₂C(O)H] and glycolaldehyde [HOCH₂C(O)H], whereas formaldehyde [HC(O)H], 2-hydroxybutanal [CH₃CH₂CH(OH)C(O)H] and the epoxide P18 are anticipated to be minor products. The calculated results are consistent with the recent experimental observations.     

The C–D Stretch of Monodeuterated Propargyl Radical (CH2CCD)

The high-resolution infrared spectrum of the monodeuterated propargyl radical (CH₂CCD) has been obtained in the region of its acetylenic C–D stretch. Lower state rotational constants were determined for the molecule. The upper state was significantly perturbed making the upper state rotational constants determined much more uncertain.     

CH3CH2+O(3P)反应机理的理论研究

利用abinitio方法对CH3CH2+O(3P)反应进行了理论研究,在MP2/6311+G(d,p)水平上优化得到了反应途径上的反应物、中间体、过渡态和产物的几何构型和谐振频率,并在QCISD(T)/6311+G(d,p)水平上进行单点能计算.计算结果表明:CH2O+CH3、CH3CHO+H和CH2CH2+OH是主要反应产物,其中CH2O+CH3主要来自反应通道A1:(R)→IM1→TS3→(A),CH3CHO+H主要来自反应通道B1:(R)→IM1→TS4→(B),CH2CH2+OH主要来自直接抽提反应通道C1和C2:(R)→TS1(TS2)→(C).计算结果同时表明该反应生成CO的通道能垒是非常高的,CO应该不是主要产物.     

CH3CH2+N(4S)反应机理的理论研究

利用abinitio方法对CH3CH2+N(4S)反应进行了理论研究,在MP2/6-311+G(d,p)水平上优化得到了反应途径上的反应物、中间体、过渡态和产物的几何构型和谐振频率,并在QCISD(T)/6-311+G(d,p)水平上进行单点能计算.计算结果表明,CH2CH2+3NH和H2CN+CH3是此反应主要产物,CH3CHN+H是此反应次要产物.产物CH2CH2+3NH主要来自直接氢抽提反应通道,H2CN+CH3来自加成-解离反应通道,CH3CHN+H来自加成-解离反应通道.     

Mechanical Properties of Materials Based on Graphene C62H20 and Polyethylene (–CH2–CH2–)n

Technical Physics - The mechanical properties of materials based on graphene C62H20 and polyethylene (–CH2–CH2–)n have been studied using the semiempirical PM3 method, and visual...     

Collision-induced rototranslational absorption spectra of binary methane complexes (CH4CH4)

Existing rototranslational collision-induced absorption (CIA) spectra of methane pairs are analyzed with the help of spectral profiles computed from quantum mechanics. Dipoles induced by octopolar and hexadecapolar fields, hexadecapolar overlap, and the gradient of the octopolar field are considered. The spectral contributions of both bound and free pairs of molecules are accounted for. The analysis which suggests a centrifugal distortion of rotating methane molecules permits one to reproduce from theory the measured CIA spectra at all temperatures (126–300 K) and over the full range of frequencies (> 700 cm⁻¹ at high temperatures) with rms deviations that are smaller than the experimental uncertainties. The values of the octopole and hexadecapole moments of (nonrotating) CH₄ molecules needed for that purpose are consistent with state-of-the-art ab initio computations for the first time in such work.     

Low-temperature x-ray diffraction studies of the crystallographic parameters and thermal expansion of (CH3)2NH2Al(SO4)2 · 6H2O crystals

The a, b, c, and β crystallographic parameters of the (CH₃)₂NH₂Al(SO₄)₂ · 6H₂O crystal (DMAAS) have been measured by x-ray diffraction in the 90–300-K temperature range. The thermal expansion coefficients along the principal crystallographic axes α_a, α_b, and α_c have been determined. It was shown that, as the temperature is increased, the parameter α decreases and b increases, whereas c decreases for T<T _c (where T _c is the transition temperature) and increases for T>T _c, so that one observes a minimum in the c=f(T) curve in the region of the phase transition (PT) temperature T _c ～ 152 K. The thermal expansion coefficients α_a, α_b, and α_c vary in a complicated manner with increasing temperature, more specifically, α_a and α_c assume negative values at low temperatures, and the α_a=f(T), α_b=f(T), and α_c=f(T) curves exhibit anomalies at the PT point. The crystal has been found to be substantially anisotropic in thermal expansion.     

磷酸盐激光玻璃聚(CH3)2 Si(OC2 H5)2防潮膜

以（CH3）2Si（OC2H5）2为前驱体,采用溶胶-凝胶与有机合成相结合的方法,制得稳定性良好的涂膜液。采用旋转涂膜法在掺钕磷酸盐激光玻璃棒端面涂制防潮膜,膜层固化后透过率达96．5％,获得的膜层表面粗糙度优良,均方根表面粗糙度（RMS）为1．659nm,平均粗糙度（RA）平均为1．321nm;在激光波长1053nm,脉冲宽度1 ns条件下膜层的激光破坏闽值可达10～14 J／cm^2。经过“神光Ⅱ”高功率激光器物理实验运行,膜层使用期为五年,并且已经在我国“神光Ⅲ”原型装置上试用。     

Ultrasonic Studies of (CH3)2NH2Al(SO4)2 · 6H2O crystals irradiated by γ quanta and electrons

The temperature dependence of the longitudinal-ultrasound velocities in (CH₃)₂NH₂Al(SO₄)₂ · 6H₂O crystals was studied using the echo-pulse technique in the 90–300 K range. The measurements were carried out along mutually perpendicular crystallographic directions X, Y, Z on samples both unirradiated and irradiated to various doses by γ quanta and an electron beam. The ultrasound velocity V in this crystal was shown to be anisotropic, with V _YY >V _XX >V _ZZ . The V _XX =f(T), V _YY =f(T), and V _ZZ =f(T) curves exhibit anomalies in the form of breaks at the ferroelectric phase transition (PT) at T _c1=152 K, as well as in the region of T _c2=218 K. It was established that as the irradiation dose increases, the PT temperature T _c1 decreases and the anomalies in the temperature dependences of the ultrasound velocities are smeared.     

Production of CH （A2△） by multi-photon dissociation of （CH3）2CO,CH3NO2, CH2Br2, and CHBr3 at 213 nm

In order to realize electrostatic Stark deceleration of CH radicals and study cold chemistry, the fifth harmonic of a YAG laser is used to prepare CH(A2△) molecules through using the multi-photon dissociation of(CH3)2CO, CH3NO2, CH2Br2,and CHBr3 at ～ 213 nm. The CH product intensity is measured by using the emission spectrum of CH(A2△→ X2Π). The dependence of fluorescence intensity on laser power is studied, and the probable dissociation channels are analyzed. The relationship between the fluorescence intensity and some parameters, such as the temperature of the beam source, stagnation pressure, and the time delay between the opening of pulse valve and the photolysis laser, are also studied. The influence of three different carrier gases on CH signal intensity is investigated. The vibrational and rotational temperatures of the CH(A2△) product are obtained by comparing experimental data with the simulated ones from the LIFBASE program.     

Electron paramagnetic resonance of the two-dimensional system Mn(CH3COO)2·4H2O

A single crystal Electron Paramagnetic Resonance (EPR) study of manganese acetate tetrahydrate was carried out at Q-band and room temperature. The EPR spectrum always reduces to a Lorentzian singlet with g=2.008. The maximum of linewidth observed along a¹ reveals the spin diffusion effects in this two-dimensional system. The maximum of linewidth observed along b reveals the exchange narrowed dipolar interactions in the linear trimers, as well as the contribution of the fine structure terms.     

Effect of γ irradiation on the heat capacity of (CH3)2NH2Al(SO4)2 · 6H2O crystals near the ferroelectric phase transition

The heat capacity of dimethyl ammonium-aluminum sulfate crystals (DMAAS), both nonirradiated and γ-irradiated to fluences of 10⁷, 5×10⁷, and 10⁸ R, has been measured by the adiabatic method near the ferroelectric phase transition (PT) within the 80–300 K temperature range. The C _p =f(T) curve exhibits a λ-shaped anomaly near the phase-transition point T _C =152 K. The PT temperature and the magnitude of the anomaly are shown to decrease with increasing γ-irradiation fluence. It has been established that the ferroelectric PT at T _C =152 K, which lies close to the tricritical point, shifts progressively more under γ irradiation toward the second-order PT, and that the behavior of the anomalous part of the heat capacity in the ferroelectric phase is described by the thermodynamic theory of Landau. The experimental heat-capacity data have been used to calculate the variation of the thermodynamic functions of the DMAAS crystal.     

LP-FTIR研究CH3C(O)CH=CH2与O3大气反应生成过氧化物的产率

在(298±2)K 温度和1.0×105 Pa(20% O2+80% N2)压力条件下,采用长光路傅里叶变换红外光谱(LP-FTIR)技术,实验室模拟研究甲基乙烯基酮(CH3C(O)CHCH2)与O3大气化学反应.从FTIR光谱中可以看出,产物中包括HCHO,HC(O)OH,CH3CHO和CH3C(O)CHO等羰基化合物,还有CO,CO2等.FTIR结合双通道过氧化物分析仪,测定了过氧化物的产率.其中,有机氢过氧化物(ROOH)为(10.7±0.4)% ,过氧化氢(H2O2)为(1.8±0.3)%.HPLC分析表明,ROOH主要为甲基过氧化氢(CH3OOH).可以认为,作为异戊二烯主要中间产物之一的甲基乙烯基酮与O3的反应是大气有机过氧化物的一个重要来源.至于反应过程中有机过氧化物的生成浓度呈现双峰的特征,其机制需作进一步的研究.     

Anharmonic effect of the dissociation rate constant of the unimolecular reactions of CH2XCHFO (X = H,F)

This study examines six unimolecular reactions of CH₂XCHFO (X?=?H,?F). The geometries of the reactions are optimized with Gaussian 03. The calculated barrier heights show that bond C–C′ scission, CH₂XCHFO (X?=?H,?F)?→?CH₂X?+?CHFO (R1), dominates the decomposition of CH₂XCHFO. For X?=?H and X?=?F, the barrier heights of (R1) are 13.37 and 9.67?kcal?mol^?1, respectively. The YL (Yao and Lin) method is used to calculate the anharmonic and harmonic rate constants of the unimolecular reactions. The results clearly demonstrate the anharmonic effect of these reactions. In the microcanonical case, for (R1) (X?=?H), the total energy is from 42.78 to 144.84?kcal?mol^?1. The corresponding anharmonic rate constants are from 1.57?×?10¹² to 2.52?×?10^13?s^?1 and the harmonic rate constants are from 1.52?×?10¹² to 2.52?×?10^13?s^?1.