High-resolution infrared analysis of the ν7 band of cis-ethylene-d2 (cis-C2H2D2)

The spectrum of the ν₇ band of cis-ethylene-d₂ (cis-C₂H₂D₂) has been recorded with an unapodized resolution of 0.0063 cm⁻¹ in the 740-950 cm⁻¹ region using a Bruker IFS 125 HR Fourier transform infrared spectrometer. By fitting 2186 infrared transitions of ν₇ with a standard deviation of 0.00060 cm⁻¹ using a Watson’s A-reduced Hamiltonian in the I^r representation, accurate rovibrational constants for ν₇ = 1 state have been derived. The band center of ν₇ has been found to be 842.20957 ± 0.00004 cm⁻¹. In a simultaneous fit of 1331 infrared ground state combination differences from the present ν₇ transitions, together with 22 microwave frequencies, ground state constants have been improved. The rms deviation of the ground state fit was 0.00027 cm⁻¹.     

The ferromagnetic and half-metallic properties of the layered organic–inorganic hybrid Fe[CH3(CH2)2PO3(H2O)]

The density-functional theory (DFT) within the full potential linearized augmented plane wave (FPLAPW) method was applied to study the layered organic–inorganic hybrid Fe[CH₃(CH₂)₂PO₃(H₂O)]. The relative stability of the ground state, the electronic band structure, the magnetic and the conducting properties were investigated. The calculations reveal that the compound has a stable ferromagnetic ground state and the spin magnetic moment per molecule is about 4.0 μ_B, which is mainly from Fe(II) ion. By analysis of the band structure, we find that the compound has half-metallic properties.     

FTIR spectra and rovibrational analysis of the ν11 band of trans-ClHCCHF and ν10 of trans-ClHCCDF

High-resolution Fourier transform infrared spectra of natural trans-ClHCCHF and of its isotopologue trans-ClHCCDF have been recorded in the region between 700 and 1150 cm⁻¹ with the purpose to analyze the ν₁₁ fundamental of the main species and the ν₁₀ of its deuterated compound. Both bands, of symmetry species A″, present c-type envelope absorptions. Beside the expected features, the K structure of the P(J), Q(J), and R(J) manifolds was resolved and identified; the assignment of the rovibrational transitions was extended up to J = 92 and K_a = 13 for the trans-³⁵ClHCCHF and up to J = 86 and K_a = 10 for trans-³⁵ClHCCDF. More than 2900 and 2700 lines for the main and deuterated species, respectively, were analyzed by a least-squares procedure and reliable spectroscopic molecular parameters were determined for both isotopologues.     

Microwave synthesis, characterization, and electrochemical properties of α-Fe2O3 nanoparticles

Ultrafine α-Fe₂O₃ nanoparticles with an extremely narrow distribution were synthesized by microwave heating. Transmission electron microscopy (TEM) images showed that most primary particles have ellipsoid shapes, and the average diameter of the primary particles was less than 10 nm. The electron diffraction pattern and fringes in some particles in TEM images showed that these nanoparticles were single crystals. The BET surface area of the freeze-dried product was 217 m²/g. The initial discharge capacity of the α-Fe₂O₃ nanoparticles exceeded 1007 mA/g (cut-off voltage: 0.5 V). This large capacity corresponds to that calculated by assuming the reduction of Fe³⁺ to Fe⁰. The α-Fe₂O₃ nanoparticles also work as a rechargeable electrode material. The charge-discharge test between 4 V and 1.5 V gave a good rechargeable capacity of about 150 mAh/g.     

Time-dependent quantum dynamics study for reaction of D+CH4→CH3+HD

The semirigid vibrating rotor target (SVRT) model has been applied to the study of the reaction of D+CH_4→CH_3+HD using a time-dependent wave packet method. The energy dependence of the calculated reaction probability shows oscillatory structures similar to those observed in the abstraction reaction of H+H_2, H+CH_4 etc. We have also studied the influence of rotational and vibrational excitation of the reacting molecule (CH_4) on reaction probability. The excitation of the H－CH_3 stretching vibration gives significant enhancement of reaction probability, which rises significantly with the enhancement of rotational quantum number j. Finally, we have compared the cross section and the rate constant of the D+CH_4 system with that of the H+CH_4 system.     

CH4/H2和CH4/He体系等离子体发射光谱分析

 在CH₄/H₂和CH₄/He和CH₄/He两种系统中,利用光学发射谱技术对螺旋波放电产生低压甲烷等离子体内活性粒子的光学发射特征进行了原位诊断。在实验中,两种体系下同时都测得的主要荷电粒子为CH,Ha,Hb,Hg以及H2等。研究了各实验参数对这些活性粒子CH, Ha,Hb以及Hg的发射光谱强度的影响。结果表明：在CH₄/H₂体系下,随着射频功率的增大,Ha,Hb,Hg以及CH基团的相对强度都随着增加,而当放电气压变化时它们都呈现先增大而后减小的趋势。在CH₄/He体系下,随射频功率的增加,Ha,Hb,Hg以及CH相对强度变化的总体趋势也都是先增加而后减小,当工作气压增加时,Ha,Hb以及Hg的相对强度变化也是呈现先增大而后减小,但CH基团的相对强度却是逐渐减小的;这些结果为等离子体沉积各种薄膜过程的理解及制备工艺参数的调整提供了参考。     

Simultaneous analysis of the 2ν2, 2ν5, and ν2 + ν5 vibration-rotation bands of CH3Br

Previous studies of the parallel bands 2ν₂ and $\text{2ν}{}_5{}^0$ of CH₃Br by the two first authors have been completed by the analysis of the weaker perpendicular band ν₂ + ν₅, centered near 2745 cm^?1. It is well known that the v₂ = 1 and v₅ = 1 states of methylbromide are linked by an x-y-type Coriolis interaction. Therefore, in the 2500–2900-cm^?1 range, the levels

$\text{(v}{}_2\text{=2), (v}{}_5\text{2, l}{}_5\text{=0), (v}{}_5\text{=2, l}{}_5\text{±2), (v}{}_5\text{=v}{}_2\text{=1, l=5±1)}$

are linked by a similar interaction. Least-squares and prediction programs have been written to treat this kind of problems and they have been satisfactorily applied to both isotopic species, CH₃⁷⁹Br and CH₃⁸¹Br. A localized resonance in the K = 0 subband of ν₂ + ν₅ has been shown to be due to the 3ν₃ + ν₆ band. No evidence for a strong Fermi resonance between ν₁ and $\text{2ν}{}_5{}^0$ has been found.     

(CH3)2和(NH2)2基团修饰的齐聚苯乙炔分子电子输运性质研究

采用密度泛函理论和非平衡格林函数相结合的方法研究了S原子作为单、双端基的(CH₃)₂-OPE (齐聚苯乙炔)和(NH₂)₂-OPE分子在金电极间的电子输运性质. 通过第一性原理优化计算获得分子部分稳定结构, 再置于Au电极之间构成两极系统, 然后再优化整个两极系统获得稳定结构. 另外, 通过非平衡格林函数方法计算了两极系统的电子输运性质. 计算结果表明, 不同的修饰基团和桥接方式可以导致两极系统的开关效应、负微分电阻行为和整流行为等不同的电子输运性质. 通过计算不同偏压下的分子体系投影轨道电子分布、透射谱、态密度, 对这些新异的电输运性质出现的机理进行了解释.     

Structure and broadening coefficients (He, Ar and N2) of the ν4 band of CF4

Spectra of CF₄ in the ν₄ fundamental band region have been recorded in pure gas and in mixtures with He, Ar and N₂ at resolution up to . Obtained data allowed us to evaluate the integrated band intensity, line intensity distribution and effective broadening coefficients for J-multiplets. The broadening coefficient behavior is similar to that previously registered for linear molecules: they coincide for P and R branches; the J-dependence in the case of argon is more pronounced than that for helium. The broadening coefficients for nitrogen and helium are practically the same but the values for nitrogen are scattered around the general trend.Q-branch broadening is different from that for J-manifolds. The coefficients of branch broadening are noticeably smaller. Nitrogen broadening is very close to result for the case of argon though there is a marked difference between them for J-manifolds. Collisions with argon and nitrogen broaden the Q-branch almost 3 times more effectively than collisions with helium.     

A High-Resolution FT-IR Study of the Fundamental Bands ν6, ν10, and ν11 of trans-Glyoxal

The high-resolution Fourier transform infrared spectrum of trans-glyoxal in the gas phase has been recorded in the spectral regions 700-900 cm⁻¹, 1200-1400 cm⁻¹, and 1600-1800 cm⁻¹ with a resolution ranging from 0.0020 to 0.0025 cm⁻¹. The spectrum displays extensive rotational structures which are assigned to the three fundamental bands ν₆ (A_u, 801.5 cm⁻¹), ν₁₀ (B_u, 1732.1 cm⁻¹), and ν₁₁ (B_u, 1312.5 cm⁻¹). A total of ca. 5000 absorption lines have been assigned to these three bands. A simultaneous ground state combination difference analysis of all three bands yields improved ground state spectroscopic constants for trans-glyoxal. Furthermore, a number of spectroscopic constants for the ν₆ and ν₁₁ levels have been determined for the first time.     

Crystal field study and magnetic properties of [TbCu6(μ3OH)3(HL)2(L)4](ClO4)2·25H2O (H2L=imino-diacetic acid)

A crystal field (CF) investigation of the magnetic properties of [TbCu₆(μ₃-OH)₃(HL)₂(L)₄](ClO₄)₂·25H₂O (H₂L=imino-diacetic acid) has been carried out. An enhancement of the average magnetic susceptibility (defined by =(χ_||+2χ_⊥)/3, where χ_|| and χ_⊥ are the magnetic susceptibilities parallel and perpendicular to the symmetrical axis of the cluster) with respect to the Tb³⁺ free ion value has been noticed and is attributed to the Tb-Cu interaction. The CF parameters obtained for the system for the first time have been exploited to find the Stark splitting of the ⁷F manifold of Tb³⁺, paramagnetic resonance g-values, and the heat capacity. Two anomalies are obtained in the heat capacity at 40 and 5 K; the peak values are 3.1 and 5.98 J mol⁻¹ K⁻¹, respectively.     

High resolution FTIR spectroscopic study of the ν4 band of CH3CHF2 enclosed in a flow of cold N2 gas

An enclosive flow cooling (EFC) cell has been constructed, and coupled to a Brüker IFS 120HR high resolution Fourier transform spectrometer to record rotationally cold absorption spectra of gases of atmospheric interest at high spectral resolution. The new system has been characterized using N₂O, revealing that rotational temperatures as cold as 110 K are readily attainable using liquid nitrogen as a cryogen. Infrared spectra of the ν₄ band of 1,1-difluoroethane (R152a), CH₃CHF₂, cooled in the EFC cell have been measured at a resolution of 0.0019 . Eight hundred and twenty rovibrational transitions of the weak ν₄ band with 2?J^′?46 and K_c^′?16 were assigned and fitted to Watson’s A-reduced Hamiltonian. The ν₄ CH₃ symmetric deformation (a/c-type) was found to be coupled to the ν₁₃ asymmetric deformation (b-type) via an a-axis Coriolis interaction. In the ensuing analysis, values of spectroscopic constants were obtained for both the ν₄ and dark ν₁₃ states. Supporting ab initio calculations up to the MP2/TZV+(3df,3p) level are presented.     

Diode laser spectroscopy of the ν2 fundamental band of cis-HOPO

The absorption spectrum of the ν₂ fundamental band of the cis-conformer of the transient molecule HOPO, namely the terminal PO stretching mode, has been detected and measured using diode laser spectroscopy. The molecule was generated in a discharge flow system containing hydrogen and white phosphorus vapour (P₄) and a trace of oxygen. The spectrum has the appearance of an a-type band of a near prolate asymmetric top. Above K_a = 5 the spectrum is perturbed and transitions terminating on these higher K_a levels were excluded from the fit. The vibrational frequency and rotational constants derived from the unperturbed parts of the spectrum are compatible with new high precision ab initio calculations reported here. A combined fit of the ν₂ band and the ν₄ band data, measured earlier, was carried out. The ν₂ band origin was determined to be 1258.539525(32) cm⁻¹, approximately 5.5 cm⁻¹ higher than the matrix value.     

Line Intensity of R(0) and R(3) of the CH4 2ν3 Band from Diode Laser Spectroscopy

We have determined the spectroscopic parameters that are necessary to describe accurately the R(0) line profile of the CH₄ 2ν₃ band from about 1 Torr to a few hundred Torr of pure CH₄. The intensities determined at each pressure are in overall agreement to better than 0.7%. The R(3) manifold of the same band has also been investigated. Relative positions and absolute intensities of the three transitions composing the triplet have been determined. The intensity distribution inside the triplet is in fair agreement with recent theoretical predictions.     

Ab initio study of the electronic structure and the magnetic properties of polymers Co[N(CN)2]2(L) [L=pyrazine dioxide (pzdo) and 2-methyl pyrazine dioxide (mpdo)] with dual μ- and μ3-[N(CN)2] bridges

The first principle within the full potential linearized augmented-plane-wave (FP-LAPW) method was applied to study the compound of Co[N(CN)₂]₂(L) [L=pyrazine dioxide (pzdo) and 2-methyl pyrazine dioxide (mpdo)] with dual μ- and μ₃-[N(CN)₂]⁻ bridges. The density of states, the electronic band structure and the spin magnetic moment are calculated. The calculations reveal that these two compounds have a ferromagnetic (FM) interaction arising from the 1,5-μ- and μ₃-[N(CN)₂]⁻ bridges. The spin magnetic moment mainly comes from the Co ion with little contribution from N, O and C anions.     

磷酸盐激光玻璃聚(CH3)2SiO/SiO2防潮膜改性研究

 采用溶胶-凝胶方法制备的(CH₃)₂Si(OC₂H₅)₂预聚体涂膜液中，掺入碱催化的SiO₂悬胶体涂膜液，采用旋涂法在掺钕磷酸盐激光玻璃棒端面涂制了改性的防潮膜。当涂膜液中(CH₃)₂Si(OC₂H₅)₂和SiO₂物质的量之比为1∶1时，热处理后的膜层耐摩擦性能明显改善；表面粗糙度的均方根值为1.245 nm；膜层激光破坏阈值大于15 J/cm²(1 053 nm，1 ns)；在80 ℃和95%RH的封闭环境中静置336 h，膜层的透过率、接触角基本不变。结果证明膜层具有稳定的疏水结构和很好的防潮性能，膜层强度增加，耐磨擦能力提高，膜层使用期延长。     

磷酸盐激光玻璃聚(CH3)2SiO/SiO2防潮膜改性研究

采用溶胶-凝胶方法制备的(CH3)2Si(OC2H5)2预聚体涂膜液中,掺入碱催化的SiO2悬胶体涂膜液,采用旋涂法在掺钕磷酸盐激光玻璃棒端面涂制了改性的防潮膜。当涂膜液中(CH3)2Si(OC2H5)2和SiO2物质的量之比为1∶1时,热处理后的膜层耐摩擦性能明显改善;表面粗糙度的均方根值为1.245 nm;膜层激光破坏阈值大于15 J/cm2(1 053 nm,1 ns);在80 ℃和95%RH的封闭环境中静置336 h,膜层的透过率、接触角基本不变。结果证明膜层具有稳定的疏水结构和很好的防潮性能,膜层强度增加,耐磨擦能力提高,膜层使用期延长。     

Mg2(BH4)2(NH2)2脱氢机理的理论研究

对Mg₂(BH₄)₂(NH₂)₂的脱氢机理展开系统的理论研究发现相对于分子内的脱氢过程,分子间的脱氢过程在热力学和动力学方面都是比较有利的. Mg₂(BH₄)₂(NH₂)₂脱氢过程的第一步是BH₄^-中的B-H^δ-和NH2-中     

Magnetic,magnetoelectric and dielectric behavior of CoFe2O4–Pb(Fe1/2Nb1/2)O3 particulate and layered composites

Magnetic, magnetoelectric and dielectric properties of multiferroic CoFe₂O₄–Pb(Fe_1/2Nb_1/2)O₃ composites prepared as bulk ceramics were compared with those of tape cast and cofired laminates consisting of alternate ferrite and relaxor layers. X-ray diffraction analysis and Scanning Electron Microscope observations of ceramic samples revealed two-phase composition and fine grained microstructure with uniformly distributed ferrite and relaxor phases. High and broad maxima of dielectric permittivity attributed to dielectric relaxation were found for ceramic samples measured in a temperature range from −55 to 500 °C at frequencies 10 Hz–2 MHz. Magnetic hysteresis, zero-field cooled (ZFC) and field cooled (FC) curves, and dependencies of magnetization on temperature for both magnetoelectric composites were measured with a vibrating sample magnetometer in an applied magnetic field up to 80 kOe at 4–400 K. The hysteresis loops obtained for composites are typical of a mixture of the hard magnetic material with a significant amount of the paramagnet. The bifurcation of ZFC–FC magnetizations observed for both composites implies spin-glass behavior. Magnetoelectric properties at room temperature were investigated as a function of dc magnetic field (0.3–7.2 kOe) and frequency (10 Hz–10 kHz) of ac magnetic field. Both types of composites exhibit a distinct magnetoelectric effect. Maximum values of magnetoelectric coefficient attained for the layered composites exceed 200 mV/(cm Oe) and are almost three times higher than those for particulate composites.     

CH3OH/TiO2(110)界面的光电子能谱研究

Methanol/TiO₂(110) is a model system in the surface science study of photocatalysis where methanol is taken as a hole capture. However, the highest occupied molecular orbital of adsorbed methanol lies below the valence band maximum of TiO₂, preventing the hole transfer. To study the level alignment of this system, electronic structure of methanol covered TiO₂(110) surface has been measured by ultraviolet photoelectron spectroscopy and the molecular orbitals of adsorbed methanol have been clearly identified. The results indicate the weak interaction between methanol and TiO₂ substrate. The static electronic structure also suggests the mismatch of the energy levels. These static experiments have been performed without band gap excitation which is the prerequisite of a photocatalytic process. Future study of the transient electronic structure using time-resolved UPS has also been discussed.