利用CARS技术研究激发态Rb2和H2的碰撞转移

利用相干反斯托克斯拉曼光谱(coherent anti-stokes Raman spectroscopy,CARS)探测技术,研究了激发态Rb2与H<,2>间的电子-振转能级的碰撞转移.扫描CARS谱确认了H<,2>分子仅在v=1,J=1,2及v=2,J=0,1,2能级上有布居,用n1,n2,n3,n4,n5分别表示...     

Hydrogen CARS thermometry in H2–N2 mixtures at high pressure and medium temperatures: influence of linewidths models

In order to improve the accuracy of H₂ CARS thermometry, H₂ Q-branch CARS spectra have been recorded for various H₂-N₂ mixtures in a high-pressure cell at different pressures and temperatures (up to 40 bar and 875 K). Due to the low spectral resolution of broadband CARS experiments, the relevant spectral lineshape factor is the linewidth ratio &(Q(3))/&(Q(1)), since Q(1) and Q(3) are the most intense lines of the Q-branch spectrum in this temperature range. For the first time, the speed-inhomogeneous effects are accounted for in the simulation of the CARS profiles. The evaluated temperatures are in good agreement with reference values obtained by thermocouples. The specific role on the accuracy of H₂ CARS thermometry of the speed inhomogeneity is carefully analyzed, in connection with the influence of the nitrogen concentration.     

A study of the ground states of CaC2H2+,CaC2D2+ and CaC2H4+

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Transport properties of H–N2 mixtures

Transport coefficients (shear viscosity, volume viscosity, thermal conductivity, and mass and thermal diffusion coefficients) of H–N₂ mixtures in the dilute-gas limit have been calculated from the intermolecular potential in the temperature range 300–2000K using the classical trajectory method. The intermediate results pertaining to H–N₂ binary interactions are reported, mainly in terms of cross-section ratios. Cross-sections evaluated with the Mason–Monchick approximation yield very good results for this system, the largest deviations, about 2.5%, being observed for the thermal diffusion coefficient. The accuracy here of this approximation can primarily be attributed to a light H atom and a weakly non-spherical potential resulting in a high rotational collision number. Furthermore, we investigate to which H–N₂ cross-sections and their ratios the values of the mixture transport coefficients are most sensitive. Our results indicate that, for some cross-section ratios, reliance on universal correlations at high temperatures, often used in flame codes, can induce sizeable errors in the thermal conductivity coefficient and especially in the thermal diffusion coefficients. We also observed that the volume viscosity is particularly sensitive to the value of the cross-section for internal energy relaxation in H–N₂ collisions.     

Mechanism of H2 desorption from monohydride Si(100)2 × 1H

Most recent experimental work on H₂ desorption from the monohydride Si(100) surface seems to point to a pairwise desorption mechanism involving the concerted desorption of two hydrogen atoms on different Si atoms of a single dimer. Using ab initio SCF and CI theory and a cluster model of the surface, the present work finds that the lowest energy pathway is symmetric rather than asymmetric. The desorption energy barrier is calculated to be 3.7 eV. Compared with an experimental value of 2.6 eV, the large barrier suggests that this direct desorption mechanism is not applicable. A multi-step desorption mechanism which involves a delocalized process in the formation of dihydride SiH₂ and a localized desorption of H₂ is proposed and is shown to explain the experimental observations.     

微机控制的CARS实验装置及三氯甲烷的CARS谱

用 ＡＰＰＬＢ ＩＩ微机实现了包括激光触发，波长调谐，相位匹配角计算和调整，探测波长自动跟踪以及数据采集和处理等过程的ＣＡＲＳ（相干反斯托克斯拉曼散射）实验目动化．给出了三氯甲烷的ＣＡＲＳ谱，证明了装置的可靠性．     

火焰中N_2分子CARS谱及温度测量

本文实现了对乙炔/空气火焰中N_2分子CARS谱的测量,同时也进行了N_2分子CARS谱的理论计算,通过实验测量与理论计算比较,确定了火焰的温度.其结果与我们用OH基荧光方法测量的结果基本符合.     

Magnetization of type-ii superconductors in the range of fields H c 1 ≤ H ≤ H c 2Variational Method

A variational method is proposed to find the magnetic field dependence of the magnetization of type-II superconductors in the mixed state by a self-consistent technique. This model allows for suppression of the order parameter to zero at the centers of Abrikosov vortices and also for the magnetic field dependence of the order parameter. The results can be applied to the entire range of fields H _c 1 ≤ H ≤ H _c 2 for any values of the Ginzburg-Landau parameter $\kappa > 1/\sqrt 2$ . It is shown that in weak fields where κ ? 1 the behavior of the magnetization can be described exactly in the London approximation provided that the correct value of H _c 1 is used. Near the second critical field this dependence shows good agreement with the well-known Abrikosov result. It is also shown that using the concept of isolated vortices and applying the principle of superposition of the fields and currents generated by these vortices to calculate the magnetization gives inaccurate quantitative results even in fairly weak fields. By going beyond these concepts, it was possible to allow more accurately for the influence of the vortex cores on the magnetization behavior in the intermediate range of fields H _c 1 ?H ? H _c 2 and to identify the range of validity of various approximations used widely in the literature.     

The H—H+, H+—H+ and H—H fragmentation in the collision-induced dissociation of H 2 + ions

The collision-induced dissociation of 10 keV H ₂ ⁺ ions incident on H₂ has been studied in this paper. Total cross sections and angle distributions for the H⁺-H, H⁺-H⁺ and H-H fragmentations are given. Distributions over both angle and velocity have been measured for the H-H⁺ and H-H fragmentation.     

Molecular Dynamics Study of gases H2,D2 and T2

The classical Molecular dynamics simulation has been used to study the equation of state of gas H2,D2 and T2.It has also been investigated that the isotope mass affects on the accuracy of equation of state.Our calculated Iesults show that the classical effect is principal and the isotope mass effects on the equation of state are obvious for the much light gases.At the same time,some useful theoretical data of equation of state for these gases have been provided.It is found that the classical simulation is still effective to the quantum gas.However,the quantum mechanics simulation and the improvement of intermolecular interaction potential are necessary if more accurate computational results are expected.     

A new analysis of the ν2 fundamental band of H2O^＋＊

This paper reports that the absorption spectra of H2O^＋ have been measured by tunable mid-infrared diode laser spectroscopy in the spectral range of 1100-1380 cm^-1. The H2O＋ ions are generated in an AC glow discharge of the gaseous mixtures of H2O/He and detected with the velocity modulation technique. Forty new lines are assigned to the ν2 fundamental band of H2O^＋ （X^2B1）. The observed lines together with other data published previously are fitted to the standard effective Hamiltonian of an asymmetric top, yielding a set of improved rotational constants, spin-rotation constants and their quartic and sextic centrifugal distortion constants for the ν2=1 vibrational state of H2O＋.     

Study of the ν2 + ν10 Hybrid Band of the Trans-C2H2D2 Molecule

Russian Physics Journal - The ν2 + ν10 (Bu) hybrid band of the trans-C2H2D2 molecule in the region 2100–2300 cm–1 is studied for the first time. The spectrum has been analyzed...     

Dissociation and Coulomb Explosion of H2^4＋ in S^q＋ ＋H2 Collisions

We have investigated fragment emission from molecularions in H2^r collisions between S^q and H2 with incident energies of 12.5, 15.625, 18.75, 21.875, 25, 28.125, 31.25, 34.375, 37.5, 40.625, and 43.75 keV/u, respectively. The energy distributions of the fragments are measured by time-of-flight techniques. The experimental results show evidences for molecular Coulomb explosion and dissociation. A program[1] is estab-lished based on the Monte Carlo technique to simulate the time-of-flight spectrum of fragment ions with different initialkinetic energy in ion-Molecule collisions. Simulations are done for S^2 H2 collisions and compared with experimental results.     

Electromotive force of a COCO2 sensor in COCO2H2H2O atmospheres and simultaneous determination of partial pressures of CO and CO2

The electromotive force (EMF) of the COCO₂ sensor using Na₂CO₃ and NASICON (Na₃Zr₂Si₂PO₁₂) as solid electrolytes has been examined in COCO₂Ar atmospheres. The EMF is related to the partial pressures of CO and CO₂ and proportional to log(P²_CO2P⁻¹_CO). The simultaneous use of the oxygen sensor of stabilized zirconia gives the EMF proportional to log(P_CO2P⁻¹_CO). The EMF's of two sensors permit to determine individually partial pressures of CO and CO₂. The existence of H₂ with high concentration does not affect the EMF's. This fact proves the applicability of the two-sensor system to the monitoring and the controlling of reducing atmospheres in industrial processes.     

Nuclear Magnetic Resonance Relaxation Study of the Phase Transitions of Rb2CuCl4·2H2O and Cs2MnCl4·2H2O Single Crystals

The physical properties and phase transitions of Rb₂CuCl₄·2H₂O and Cs₂MnCl₄·2H₂O crystals were investigated by performing ⁸⁵Rb, ⁸⁷Rb, and ¹³³Cs nuclear magnetic resonance relaxation analyses. The temperature dependences of the spectra and the spin–lattice relaxation times T ₁ near T _C are related to changes in the symmetry of the octahedrons consisting of four Cl⁻ ions and two water molecules around Rb⁺ or Cs⁺; the forms of these octahedrons are disrupted by the loss of H₂O. The difference between the relaxation times of the two crystals is possibly due to the difference between the electron structures of the Cu and Mn ions. Cu²⁺ has nine valence electrons in its 3d orbital, whereas Mn²⁺ has five valence electrons in its 3d orbital.