H2D库仑爆炸中的同位素效应与尾流效应

对H2D+通过碳膜后的产物H+和D+的获取与测量,研究了H2D+的同位素效应以及离子穿过固体的尾流效应.H2D+的化学结构得到测定.H2D+的非对称结构得到确认.测量结果与通过其它方式对H2D+的研究结果相一致.     

利用尾流效应确定HD2+的结构与核间距

在研究HD2+ 与固体膜的相互作用时, 发现在HD2+ 穿过固体时产生了较强的尾流效应, 并在确定HD2+作的结构时, 尾流效应起到了关键的作用. 这一技术的使用, 可以使得许多使用传统方法无法确定的分子离子结构寻求到一种方法和手段. 本文就如何使用尾流效应来确定HD2+ 结构作一报道. 这种方法的基本思想是,库仑爆炸能谱图普相对于分子离子的核间距时非常是非常敏感的.     

利用尾流效应确定HD2+的结构与核间距

在研究HD2+ 与固体膜的相互作用时, 发现在HD2+ 穿过固体时产生了较强的尾流效应, 并在确定HD2+作的结构时, 尾流效应起到了关键的作用. 这一技术的使用, 可以使得许多使用传统方法无法确定的分子离子结构寻求到一种方法和手段. 本文就如何使用尾流效应来确定HD2+ 结构作一报道. 这种方法的基本思想是,库仑爆炸能谱图普相对于分子离子的核间距时非常是非常敏感的.     

HD2+通过超薄碳膜的"尾流"效应

快分子离子穿过固体时会产生库仑爆炸(Coulomb Explosion),尾流效应是库仑爆炸中的一个显著特性.HD2 的爆炸能谱在实测中发现了一些引人注目的特性:1)H 的尾流效应特别显著;2)H 的能谱结构非常类似HeH 中H 的能谱;3)尾流效应在D 的能谱中体现得很弱.这些特性对分析了解HD2 的结构和物理化学性质有很大的帮助.本文依照“尾流”效应(Wake Effect)的等离子体模型,将爆炸中两个D 产物的尾流场近似认为一个He 的尾流场,模拟计算了1.4977 MeV HD2在100 nm碳膜中分解后0°方向的能谱形式.给出了相同条件下的实验结果,得到了非常接近的结果,并将两者作了比较和分析.文中同时给出了D 的实验能谱,对D 的尾流效应相对较弱作了分析,指出对不同产物分辨的差异、产物的非直线运动等是造成D 尾流效应弱的原因.     

HD2+,H3+和D3+与固体相互作用和三体尾流效应

从分子离子H3 及其氘化同位素分子离子D3 和HD2 与超薄固体膜相互作用发生库仑爆炸为基础,分析讨论了H3 ,D3 和HD2 三种分子离子的形成机理,根据产物能谱分布,利用库仑爆炸技术确定了同位素分子离子HD2 的结构形式,给出具体核间距数值.并确定在实验中不存在线状结构的HD2 .提出一种三原子分子离子和固体相互作用中尾流效应的处理方式,通过和实验结果做比较发现这是一种非常理想的处理三体尾流效应的模式,并用之进一步确认了HD2 的结构形状.文章对H3 ,D3 和HD2 三种分子离子的实验结果做了对比和讨论.     

Triatomic wake effect and the determination of the molecular structure of HD2+ from the Coulomb explosion

A new theoretical model of the triatomic molecular wake effect is proposed and applied to molecular ions D+ 3 and HD+ 2 while passing through a solid.The wake effects resulting from the reactions of the two similar ions with thin carbon foil are also investigated by using the Coulomb explosion technique.The experimental results are in good agreement with theoretical estimates and the molecular structure of HD+ 2 is determined by using the model.     

Charge asymmetry and rovibrational excitations of HD+

Average values of the interparticle distances for rovibrationally excited HD⁺ are calculated using a method where the Born–Oppenheimer (BO) approximation is not assumed. The difference between the proton–electron and deuteron–electron distances is used to describe the charge asymmetry in the system. All-particle one-centre explicitly correlated Gaussian functions are used in the calculations of the HD⁺ rovibrational states. In this work, the non-BO method is extended to calculate the rovibrational states corresponding to the total rotational quantum number of two (N = 2). The algorithms for calculating the Hamiltonian and overlap matrix elements, and the matrix elements of the analytical energy gradient determined with respect to the exponential parameters of the Gaussians, are presented. The gradient is employed in the variational optimisation of the parameters, which is key in obtaining very accurate rovibrational energies in the calculations. The algorithm for calculating the average interparticle distances is also shown. The charge asymmetry of HD⁺ near the dissociation limit occurs, as expected, with the electron preferentially being near to the deuteron. The asymmetry for a particular vibrational level increases with rotational excitations. The rovibrational transition energies are also calculated and compared with available experimental data.     

Cassiopeia A: Supernova explosion and expansion simulations under strong asymmetry conditions

We propose a model for the explosion of a supernova and the expansion of its ejecta in the presence of a strong initial asymmetry (at the explosion time) in the central part of the star (core) and a possible smallscale asymmetry in the peripheral regions. The Chandra and NuSTAR observations of ejecta in the Cassiopeia A supernova remnant are analyzed. Based on our 1D and 2D numerical simulations performed using the DIANA and NUTCY codes, we propose a model for the explosion and expansion of ejecta that explains the observed experimental data where the materials initially located in the central region of the star end up on the periphery of the cloud of ejecta.     

Comparison of structure factors and pair correlation functions obtained using coulomb attractive potential and screened coulomb potential for the suspended macroions

The structure factors and pair correlation functions have been calculated for the macroions suspended in water using coulomb attractive potential (CAP) and the results have been compared well with the results obtained from the RMSA and MMSA using screened coulomb potential (SCP). Differences among the values of compressibility in the limit of zero momentum transfer, excess energy per macroion and coordination number for both the potentials have been reported. Liquid like ordering of the FCC type has been obtained using both CAP as well as SCP potentials between suspended macroions.     

Static Stark effect in the molecular ion HD+

We present preliminary results on the Stark effect of the hyperfine levels of the molecular ion HD⁺.     

High-precision calculation of the hyperfine structure of the HD+ ion

High-precision laser spectroscopy of ultracold hydrogen molecular ions has the potential of improving the precision of the electron-to-proton mass ratio. An accurate knowledge of the spin structure of the transition is required in order to permit precise comparison with experimental transition frequencies. We calculate with a relative accuracy of the order of O(alpha2) the hyperfine splitting of the rovibrational states of HD+ with orbital momentum L相似文献   

利用快分子离子与固体的相互作用对H2+,HD+和D+2结构的研究

利用快分子离子与固体的相互作用,依靠一套高分辨装置,测量了H2+,HD+和D2+的结构,得到其核间距分别为1.19±0.003 nm、1.25±0.003 nm和1.32±0.003 nm.通过对比,证实了分子离子结构中同位素效应的存在,分析了实验值和理论值存在差别的原因,讨论了实验结果中同位素效应产生的缘由.     

Dynamics and control of shock shells in the coulomb explosion of very large deuterium clusters

The explosion dynamics of very large (approximately 10(6)-10(7) atoms) deuterium clusters irradiated by ultraintense laser pulses (I approximately 10(18) W/cm(2)) is analyzed self-consistently with one-to-one three-dimensional and two-dimensional fully relativistic particle-in-cell simulations. Small-scale shock shells in the expanding ion cloud are observed. A technique to induce the formation of large shock shells inside a single cluster, increasing the probability of intracluster nuclear reactions, is proposed and demonstrated.     

Quantum stereodynamics study for the reaction F + HD

This paper studies the quantum stereodynamics of the F + HD(υ = 0, j = 0) → HD + F/HF + D reaction at the collision energies of 0.52 and 0.87~kcal/mol. The quantum scattering calculations, based on Stark-Werner potential energy surfaces, show that the differential cross sections for the HF(υ' = 2) + D and DF(υ' = 3) + H channels are consistent with the recent theoretical results. Furthermore, the product rotational angular momentum orientation and alignment have been determined for some selected rovibrational states of the HF + D and DF + H channels.     

The role of the electron-hole coulomb interaction in quantum confined stark effect

The luminescence peak energy and tunneling lifetime of an exciton in a semiconductor quantum well with a small valence band offset in the presence of a perpendicular electric field is calculated by generalizing the variational approach of quantum confined Stark effect normally used for systems of GaAs/AlGaAs quantum wells. At a finite electric field, the electron-hole Coulomb interaction provides additional confinement to each of the carriers and significantly enhances the Stark shift and the exciton lifetime against field ionization. Numerical results are presented for ZnSe/Zn_1−xMn_xSe heterostructures studies in recent experiments.     

The dipole polarizability of the hydrogen molecular cation HD+ and other isotopomers

Fully non-adiabatic calculations are reported of the electric dipole polarizabilities for the N = 0 and N = 1 levels of the ground electronic states of H⁺ ₂ (ν ≤ 16), D⁺ ₂ (ν ≤ 24) and HD⁺ (ν ≤ 20). For H⁺ ₂ (ν = 0, N = 0) the calculated value still differs from the experimental value; this difference cannot be explained by the inclusion of higher order contributions.