Pressure dependence of vibrational Raman scattering of narrow-band, 248-nm, laser light by H2, N2, O2, CO2, CH4, C2H6, and C3H8 as high as 97 bar

We have previously investigated methods that image high-pressure processes such as combustion inside automobile cylinders and aircraft engines, or chemical phenomena in supercritical fluids. Here we show that vibrational Raman scattering can simply obtain, quantitatively, densities of some combustion-relevant molecules. We use narrow-band KrF excimer-laser light. Measurements for H₂, N₂, O₂, CO₂, and CH₄ are in the pressure range from 1 to 60 bar, whereas those for C₂H₆ and C₃H₈ are up to their respective vapor pressures. All these species are at ambient temperature. Additional measurements are described for CO₂ up to 96.8 bar and 318 K, where CO₂ is a supercritical fluid. The O₂ measurements are complicated by a photochemical formation of O₃; those in supercritical CO₂ by drastic bending of the laser beam within this medium. We show that, for each gas, the Raman signal is directly proportional to gas density, thereby making quantitative analysis particularly convenient. For each species, we present an estimate of its Raman cross-section relative to that of N₂. However we recommend that future diagnostics users calibrate their own systems for relative species sensitivity. Received: 23 December 1999 / Revised version: 6 June 2000 / Published online: 20 September 2000     

Tensor Force Manifestations in ab Initio Study of the 2H(d, γ)4He, 2H(d, p)3H, and 2H(d, n)3He Reactions

The ²H(d, γ)⁴He capture reaction and the ²H(d, p)³H and ²H(d, n)³He transfer reactions at very low energies are studied in an extended microscopic cluster model with a realistic nucleon–nucleon force. Our results show that the tensor force in realistic interactions plays an essential and indispensable role to reproduce the very low-energy astrophysical S factor of these reactions.     

Tensor force manifestations in ab initio study of the 2H(d,γ)4He, 2H(d,p)3H, and 2H(d,n)3He reactions

The (2)H(d,p)(3)H, (2)H(d,n)(3)He, and (2)H(d,γ)(4)He reactions are studied at low energies in a multichannel ab initio model that takes into account the distortions of the nuclei. The internal wave functions of these nuclei are given by the stochastic variational method with the AV8' realistic interaction and a phenomenological three-body force included to reproduce the two-body thresholds. The obtained astrophysical S factors are all in very good agreement with the experiment. The most important channels for both transfer and radiative capture are identified by comparing to calculations with an effective central force. They are all found to dominate thanks to the tensor force.     

Near-Threshold Low Rydberg Depletion Spectroscopy of H2, D2, and HD

Using high-resolution depletion spectroscopy, we have experimentally studied the physics of near-threshold low Rydberg states of all three stable isotopic variants of molecular hydrogen. The experiments were required to calibrate the absolute wavelength, including several transitions from the EF (v = 0) and EF (v = 6 or v = 9) to the same low-n Rydberg states. The measurements have been performed for several initial rotational levels in all three stable isotopic variants. Transitions to very high vibrational levels of the B, Bt, and C states have been measured with accuracy 0.002cm^-1. The pulsed amplifier perturbations were also measured by opticalhe terodyne methods.     

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.     

高温下H2O—Ar,H2O—CO2混合气体中H2O分子谱线的半宽度

本文用ＩＯＳ方法和我们改进的Ｂｕｃｋｉｎｇｈａｍ势计算了Ｈ２Ｏ－Ａｒ、Ｈ２Ｏ－ＣＯ２混合气体中Ｈ２Ｏ分子谱线在高温下（６００Ｋ、９００Ｋ、１２００Ｋ、１５００Ｋ）的压力展宽半宽度。分析了谱线半宽度随温度变化的规律，同时也讨论了半宽度和被加宽分子大小的关系。     

BeH,H2和BeH2的分子结构和势能函数

用二次组态相关(QCISD)和密度泛函(B3LYP)方法,选用6-311++g(d,P),6-311++g(3df,3pd)和D95(3df,3pd)基组对H2,BeH和BeH2:分子的结构进行优化.得到它们的基态电子态分别为H2(1∑g),BeH(2∑)和BeH2(1∑g),BeH2:分子的稳定构型为D∞h构型.采用最小二乘法拟合出BeH和H2分子的8参数Murrell-Sorbie函数,在此基础上推导出光谱数据和力常数;由多体项展式理论导出BeH2分子的分析势能函数.H+BeH生成BeH2(D∞h)分子存在较深的势阱,容易生成H-Be-H络合物分子.反应Be+H2+-HBeH,△H=-1.4654 eV,是放热反应.     

利用半经典微扰理论研究H—H2O的非弹性碰撞—H2O的转动,振动…

利用半经典微扰理论计算了Ｈ－Ｈ２Ｏ的非弹性碰撞中的Ｈ２Ｏ分子的转动，振动激发，并将计算结果与实验结果进行了比较。计算中采用了Ｓｃｈａｔｚ和Ｅｌｇｅｒｓｍａ的半经验势能面，水分子的势函数，包括了谐振和非谐振力函数，在考虑了振动和转动耦合的情况焉，通过半经典微扰理论来确定水分子末态的振动量子数。     

C2H2,C2H4与K在Ru（1010）表面上共吸附的UPS研究

利用紫外光电子谱(UPS)对乙烯(C2H4)和乙烯(C2H2)气体在Ru(1010)表面的吸附及与K的共吸附进行了研究,实验结果表明：当衬底温度超过200K,乙烯即发生脱氢反应后,σCH和σCC能级均高结合方向移动．在室温下、σCH和σCC能级位置与乙炔在Ru(1010)表面的吸附时的分子能级完全一致．乙烯发生脱氢反应后的主要产物为乙炔。衬底温度从120K升到室温,Ru(1010)表面上乙炔的σCH和σCC能级均未发现变化．室温下乙炔仍然可以在Ru(1010)表面以分子状态稳定吸附．在有K的Ru(1010）表面上．室温时σCH谱峰几乎消失．碱金属K的存在促进了乙炔的分解．     

Theoretical Investigation on Excitation,Ionization and Capture in H（1s, 2s） ＋ H（1s, 2s） Collisions

Cross sections of electron-loss in H（1s）＋ H（1s） collisions and total collisional destruction of H（2s） in H（1s） 4- H（2s） collisions are calculatted by four-body classical-trajectory Monte Caylo （CTMC） method and compared with previous theoretical and experimental data over the energy range of 4-100 keV. For the former a good agreement is obtained within different four-body CTMC calculations, and for the incident energy Ep 〉 10 keV, comparison with the experimental data shows a better agreement than the results calculated by the impact parameter approx- imation. For the latter, our theory predicts the correct experimental behaviour, and the discrepancies between our results and experimental ones are less than 30%. Based on the successive comparison with experiments, the cross sections for excitation to H（2p）, single- and double-ionization and H- formation in H（2s）＋H（2s） collisions are calculated in the energy range of 4-100 keV for the first time, and compared with those in H（1s）＋H（1s） and H（1s）＋U（2s） collisions.     

用含时波包理论处理HD＋H→H＋DH,D＋H2反应

用含时波包（ＴＤＷＰ）理论计算了具有两个不同产物道的反应ＨＤ＋Ｈ→Ｈ＋ＤＨ，Ｄ＋Ｈ２的初态确定的反应几率及生咸物的分支比。在利用分解算符法进行波包传播的过程中，采取了分立变量表象（ＤＶＲ）及分立交量－有限基表象（ＤＶＲ—ＦＢＲ）变换，这一方法降低了传播过程中需保存大变换矩阵的要求。通过应用能量投影法，可从单一波包中抽出许多能量确定的动力学信息。为了避免因所选取的格点范围有限而引起的波函数在边界点附近的反射，传播过程中还采用了光学势以吸收反射波函。     

Structural characterization,thermal, ac conductivity and dielectric properties of (C7H12N2)2[SnCl6]Cl2·1.5H2O

(C₇H₁₂N₂)₂[SnCl₆]Cl₂·1.5H₂O is crystallized at room temperature in the monoclinic system (space group P2₁/n). The isolated molecules form organic and inorganic layers parallel to the (a, b) plane and alternate along the c-axis. The inorganic layer is built up by isolated SnCl₆ octahedrons. Besides, the organic layer is formed by 2,4-diammonium toluene cations, between which the spaces are filled with free Cl^? ions and water molecules. The crystal packing is governed by means of the ionic N—H···Cl and Ow—H···Cl hydrogen bonds, forming a three-dimensional network. The thermal study of this compound is reported, revealing two phase transitions around 360(±3) and 412(±3) K. The electrical and dielectric measurements were reported, confirming the transition temperatures detected in the differential scanning calorimetry (DSC). The frequency dependence of ac conductivity at different temperatures indicates that the correlated barrier hopping (CBH) model is the probable mechanism for the ac conduction behavior.     

Two triple points in the H2O–H2 system

Using a volumetric technique, phase transitions in the H₂O–H₂ system were investigated in the vicinity of two points of an invariant equilibrium, L+I _h+sII and L+sII+C ₁, located at 1.07 kbar and?10 °C and at 3.6 kbar and 1 °C, respectively. Liquid water (L), low-pressure hexagonal ice (I _h) and high-pressure cubic (sII) and rhombohedral (C ₁) clathrate hydrates were in equilibrium with gaseous hydrogen taken in excess.     

Ar^2＋离子和H2,O2分子碰撞过程中激发态的研究

在Ar~(2 )离子和H_2,O_2分子碰撞实验研究中,发现这两个碰撞体系都存在三个激发通道:(1)双电子俘获激发通道,(2)单电子俘获激发通道,(3)靶直接激发通道。实验结果得到了ArⅠ,ArⅡ和HⅠ,OⅠ的发射截面,并分别比较了Ar~(2 ) H_2,Ar~(2 ) O_2,He~(2 ) H_2,He~(2 ) O_2碰撞体系的发射截面。     

50-5000 eV电子被C4H8O, C5H10O2, C6H5CH3和C4H8O2散射的总截面

使用电子被C, H和O原子散射总截面的实验数据, 利用修正后的可加性规则计算了能量为50-5000 eV的电子被4个复杂大分子C4H8O, C5H10O2, C6H5CH3和C4H8O2散射的总截面, 并将计算结果与实验结果及其他理论计算结果进行了比较. 结果表明, 即使是在几十电子伏的入射能量下, 修正后的可加性规则计算出的总截面依然能与实验结果符合很好, 而使用未修正的可加性规则进行计算, 即使是在几百电子伏的入射能量下得到的总截面仍偏离实验值较远. 分析表明, 未修正的可加性规则计算得到的总截面在中低能区过大、随电子入射能量的增加而衰减太快的问题是由可加性规则本身引起的, 其实质是未考虑低能下分子内原子间的相互屏蔽对散射总截面的计算所带来的影响.