U (2) algebraic model applied to vibrational spectra of Nickel Metalloporphyrins

In this paper the highly excited stretching and bending vibrational energy levels of some Nickel Metalloporphyrin molecules are studied by U (2) algebraic model. Its application to Nickel Octaethyl Porphyrin, Nickel Tetra Phenyl Porphyrin and Nickel Porphyrin are presented with fewer algebraic fitting parameters. The highly excited stretching and bending vibrational energy levels of these molecules are showing the energy clustering spectrum.     

双原子离子振动光谱与离解能的研究

结合代数方法(AM)和最近建立的计算精确的分子离解能的新解析表达式,进一步研究了部分双原子离子电子态的完全振动能谱和离解能,获得了与实验值符合得非常好的理论结果.研究结果表明,AM方法和新解析式相结合的理论方法同样也适用于双原子离子体系,该方法在理论上提供了获得双原子离子精确的振动光谱和离解能的物理新方法.     

Analysis of vibrational spectra of nano-bio molecules： Application to metalloporphrins

In this paper, we have applied the Lie algebraic model to nano-bio molecules to determine the vibrational spectra of different stretching and bending vibrational modes. The determined vibrational energy levels by the Lie algebraic model are compared with the experimental data. The results from the theoretical mode[ are consistent with the experimental data. The vibrational energy levels are clustering in the excited states.     

Density functional study of the molecular structures,infrared and Raman spectra of carbon suboxide,its sulfur and selenium analogues

Carbon suboxide, and its sulfur and selenium analogues in D _∞h symmetry have been studied in the gas phase by a density functional method using B3LYP as the functional. The basis sets employed are 6-31++G(d,p), 6-311++G(d,p), cc-pVDZ and all calculations have been carried out using Gaussian 03W. Molecular parameters, namely bond lengths, rotational constants, quadrupole moments, and infrared and Raman frequencies are predicted for these molecules. Atomization energies have also been predicted. The calculated molecular parameters and vibrational spectra of the parent molecule, namely carbon suboxide, are in good agreement with literature data. Therefore, data from the present theoretical gas phase study are expected to be valid for the molecular structures and vibrational spectra of carbon subsulfide and carbon subselenide. The results from this study could be used as a reference for these molecules.     

Vibrational frequency and force field constant calculation of CH3OH and its 9 isotopomers by GF matrix method

A total 75 observed vibrational frequencies from 8 isotopomers in methanol have been fitted to a least-squares programme and a set of force constants which includes 21 parameters are obtained. Using this set of parameters, the G and F matrix calculations yield the vibrational frequencies for 10 isotopomers of methanol. The calculated results also show that the different vibrational modes are mixed. This calculation can be readily extended to other similar molecules.     

Vibrational excitation and negative ion production in radio frequency parallel plate H2 plasmas

A theoretical study of the vibrational kinetics and attachment in low pressure hydrogen plasmas produced by Radio Frequency (RF) discharges is performed. In particular we study the influence of gas/surface kinetic processes such as the vibrational deactivation and the atomic recombination of molecules. The production of vibrationally excited molecules by the surface recombination of atoms is also considered. The study is realized by means of a self-consistent one dimensional kinetic model, and a parallel plate RF discharge test case is implemented. Results show that surface processes are able to affect the vibrational distribution function (vdf) and the negative ion (H-) density. The effect of vibrational exothermicity of H atom recombination is also discussed as a way to reduce the gap between theory and experimental results. Moreover, it is shown that the H- ion heating by the electric field strongly affects the detachment rate: this effect is specially important for negative ions produced through Rydberg states in this kind of discharges.     

Vibration-inversion-rotation spectra of ammonia. A vibration-inversion-rotation Hamiltonian for NH3

A new model Hamiltonian has been developed to study the vibration-inversion-rotation energy levels of ammonia. In this model the inversion motion is removed from the vibrational problem by allowing the molecular reference configuration to be a function of the large amplitude motion coordinate. The treatment follows closely that developed by Hougen, Bunker, and Johns for the study of triatomic molecules.The numerical methods that have been used to solve the zeroth-order Hamiltonian describing the inversion-rotation energy levels of NH₃ and ND₃ in the ground vibrational state are discussed. Certain group-theoretical problems concerning the symmetry classification of the states of ammonia are also discussed.     

Role of binding energy in Feshbach-resonant positron-molecule annihilation

Measurements of positron-on-molecule annihilation have established that positrons bind to a variety of molecules via vibrational Feshbach resonances. Data for deeply bound states in benzene and 1-chlorohexane and for positronically excited (i.e., second) bound states in alkanes are used to establish the dependence of annihilation rates on the binding energy and incident positron energy. With this dependence removed, annihilation rates for a broad class of molecules lie on a universal curve as a function of the number of molecular vibrational degrees of freedom. The implications of these results for theoretical models are discussed.     

Vibrational relaxation dynamics in transient grating spectroscopy studied by rate equations based on time-dependent correlation function

A modified model, a set of rate equations based on time-dependent correlation function, is used to study vibrational relaxation dynamics in transient grating spectroscopy. The dephasing, the population dynamics, and the vibrational coherence concerning two vibrational states are observed respectively in organic dye IR780 perchlorate molecules doped polyvinyl alcohol matrix. The result shows that in addition to the information concerning system-environment interac- tion and vibrational coherence, the vibrational energy transfer can be described by this modified model.     

Li_2部分电子态的完全振动能谱与离解能的精确研究

本文将孙卫国等建立的精确计算双原子分子离解能的解析表达式作为分子振动能级正确收敛的重要物理判据,应用代数方法,进一步研究了重要的碱金属Li2的5个电子态的完全振动能谱和离解能,获得了这些电子态的精确振动光谱常数,同时也得到了包括接近分子离解极限在内的完全振动能谱和与实验值符合得很好的理论离解能.这些计算结果为许多需要这些电子态振动数据的研究领域提供了重要的研究数据.     

The vibrational Zeeman effect

The theory of the vibrational Zeeman effect in symmetric top molecules is presented. It is shown that vibrational g factors may be related to rotational g factors and estimates are made of their magnitude for a number of molecules; these calculations indicate that vibrational Zeeman effects should be observable in symmetric top molecules in degenerate vibrational states. In addition, the novel features of the theory for linear molecules are discussed.     

双原子分子振动能谱与离解能的精确研究

代数方法(AM)的建立解决了实验方法和精确量子力学理论方法难以获得双原子分子的包含最高振动能级在内的所有高阶振动能级的精确数值这一问题.基于LeRoy与Bernstein的工作,孙卫国等又建立了精确计算双原子分子离解能的新解析表达式.应用新公式和代数方法(AM),研究了一些双原子分子部分电子态的振动能谱和分子离解能,获得了与实验值符合非常好的理论结果.该方法在理论上提供了获得双原子分子完全振动能谱和精确分子离解能的物理新方法.     

Molecular vibration dynamics in molecule-surface interactions

A quantum mechanical coupled channels approach to associative or recombinative desorption and scattering of diatomic molecules is described. The formulation is based on the concept of a reaction path and allows prediction of the vibrational excitation of desorbing molecules. We first consider very light molecules such as H₂ and D₂ desorbing via a Langmuir-Hinshelwood reaction. In a simple model neglecting rotations and substrate vibrations, the dependence of molecular vibrational excitation on incident energy, the curvature of the reaction path and the position and height of the saddle point are discussed. Various experimental results can be described with reasonable parameters. Vibrational excitation in Eley-Rideal reactions and rotational excitations in general are discussed only in a semiquantitative way. For heavier molecules the coupling to substrate vibrations in principle will become more important. Arguments will be presented that for the problem of vibrational excitation in desorption and scattering this coupling may still be neglected approximately. Results for vibrational excitations of CuF desorbing from Cu are in support of this simple point of view.     

Emission Spectra of BeO in Near Ultraviolet Region

Abstract

The emission spectra of isotopic BeO molecules as excited in low-pressure arc have been photographed in the region 300–350 nm at medium dispersion. The bands have been assigned to the c³II ? a³II system. The vibrational numbering was obtained from a study of the vibrational isotope effect. Vibrational constants for involved states are derived from least-squares fits of the measured bandhead wavenumbers.     

Rotational and vibrational states of excitonic molecules in CuBr studied by the two-photon-resonant Raman scattering

Excited states of excitonic molecules are found in the study of the two-photon-resonant Raman scattering. These states consist of four levels and have binding energies of 1.0–1.8 meV, which are very small compared with those of the ground states. They are considered to be the rotational and vibrational states of excitonic molecules.     

用代数能量方法研究氢化物双原子分子的完全振动能谱和离解能

本文用研究双原子分子振动能谱的新方法-代数方法(AM),研究了KH-X1Σ+,RbH-X1Σ+,DF-X1Σ+和DCl-X1Σ+等四个氢化物双原子分子的电子基态的振动光谱常数和振动能谱;用代数能量方法(AEM)研究了相应电子态的分子离解能.研究结果表明:使用实验获得的少数精确的振动能级[Eυ],由AM方法得到的振动能谱不仅能够重复这些电子态的已知实验能级,还能够得到用现代实验方法或精确的量子理论方法很难得到的所有高振动激发态的能级.由AEM方法能够得到比用文献发表的振动光谱常数计算获得的离解能值更准确的分子离解能.     

The vibration–rotation kinetic energy operator for sequentially bonded tetra-atomic molecules in internal coordinates

An exact vibration–rotation kinetic energy operator for polyatomic molecules has been obtained. Using this Hamiltonian for sequentially bonded tetra-atomic molecules, all rovibrational terms have been derived with internal coordinates as the vibrational variables. The present approach is greatly simplified with less algebra compared with conventional methods. Also, simple and explicit expressions for the vibration–rotation coupling terms in internal coordinates are presented.     

Long-lived Feshbach molecules in a three-dimensional optical lattice

We have created and trapped a pure sample of Feshbach molecules in a three-dimensional optical lattice. Compared to previous experiments without a lattice, we find dramatic improvements such as long lifetimes of up to 700 ms and a near unit efficiency for converting tightly confined atom pairs into molecules. The lattice shields the trapped molecules from collisions and, thus, overcomes the problem of inelastic decay by vibrational quenching. Furthermore, we have developed an advanced purification scheme that removes residual atoms, resulting in a lattice in which individual sites are either empty or filled with a single molecule in the vibrational ground state of the lattice.     

吡虫啉的太赫兹(THz)光谱研究

由超短激光脉冲产生的脉冲波是具有较宽频带的电磁辐射,属于远红外波段,该波段电磁波与物质的相互作用是个崭新的研究领域。文章利用太赫兹时域光谱技术测量了室温下吡虫啉在0.2～2.0 THz范围内的吸收谱和折射率谱。结果表明吡虫啉在此波段有明显的特征吸收峰且吸收系数随频率的增加而增大,折射率也随频率的增加而有所增大,其平均折射率为1.65。实验研究的同时,运用半经验理论计算了吡虫啉分子的结构及其在太赫兹波段的振动频率,并根据计算结果对实验数据进行了解析。计算结果与实验光谱吻合得很好,实验光谱的特征吸收峰是由分子的集体振动及扭转形成, 不同的吸收峰位对应分子不同的振转模式。实验和理论研究的对比表明：分子的远红外吸收特征对于分子的结构和空间排列非常敏感,THz-TDS是研究生物分子集体振动模式和构象结构的好方法。     

Spatial and time resolved analysis of CN bands in the laser induced plasma from graphite

Analysis of the emission bands of the CN molecules in the plasma generated from a graphite target irradiated with 1.06 μm radiation pulses from a Q-switched Nd:YAG laser has been done. Depending on the position of the sampled volume of the plasma plume, the intensity distribution in the emission spectra is found to change drastically. The vibrational temperature and population distribution in the different vibrational levels have been studied as function of distance from the target for different time delays with respect to the incidence of the laser pulse. The translational temperature calculated from time of flight is found to be higher than the observed vibrational temperature for CN molecules and the reason for this is explained.