Cs2 23△1g态碰撞线归属和超精细结构解释

根据最新的Cs₂分子中间态A¹∑⁺_u -b³Πu全局解微扰获得的能级数据, 归属了通过微扰增强红外-红外光学双共振中间态A¹∑⁺_u 到上态2³△_1g的140条碰撞线, 包含之前实验观测到的221条2³△_1g←A¹∑⁺_u← X¹∑⁺_g 双共振跃迁[J. Chem. Phys. 128, 204313 (2008)], 重新计算了2³△_1g态的分子常数和势能曲线(排除54个微扰能级). 本次拟合得到的离心畸变常数和从经验公式计算得到的值相符合. 在亚多普勒激发光谱中,没有分辨出2³△_1g态的超精细结构. 对2³△_1g态的超精细结构进行初步计算,比较实验结果给出解释和说明.     

原子-异核-三聚物分子转化系统暗态的动力学不稳定性

研究了受激拉曼绝热过程中原子-异核-三聚物分子转化系统暗态的动力学稳定性.通过将量子哈密顿对应到经典哈密顿,并求解和分析线性化经典运动方程后得到的哈密顿-雅克比矩阵本征值,解析地得到了原子-三聚物暗态的动力学不稳定性发生的条件.并以异核原子⁸⁷Rb和⁴¹K混合凝聚体为例,数值地给出了系统发生动力学不稳定性的区域.研究发现,这种动力学不稳定性是由粒子之间的相互作用带来的.此外,还发现系统动力学不稳定性的发生不仅与哈密顿-雅克比矩阵是否出现实数或复数的本征值有关,还 关键词： 原子-异核-三聚物分子转化系统 暗态 受激拉曼绝热过程 动力学不稳定性     

F−(H2O)+CH3I配体交换反应动力学

本文介绍F^?(H₂O)+CH₃I→[FCH₃I]^?+H₂O在交叉分子束碰撞能量0.3∽2.6 eV的配体交换动力学成像结果. 产物的动能受到弱键结合配合物的稳定性的影响，大量水分子的内部激发不利于中间物有效的能量重新分配，随着碰撞增加，低动能受到抑制. 在0.3 eV时，内部亲核取代非常重要，为形成I^?和I^?(H₂O)的竞争性亲核取代途径提供了依据.     

四氧杂卟啉二价正离子共振拉曼光谱的TDDFT计算研究

采用DFT/TDDFF计算和极化率的态求和方法研究了四氧杂卟啉二价正离子(TOP²⁺)B态(S₂态)激发的共振拉曼(RR)光谱, 计算模型同时处理了A项和B项对拉曼极化率的贡献.用PBE1PBE、B3LYP、Cam-B3LYP、B3LYP-D3四种交换-相关泛函计算得到的RR光谱总体上相似,其中PBE1PBE和B3LYP 给出的RR 强度与实验吻合得更好一些. 对于全对称振动(A_1g),其拉曼谱带相对强度的理论计算结果与实验一致;TDDFF计算表明： 相对于基态,TOP²⁺的B态沿υ2、υ6、υ7、υ8简正模式有较大的无量纲位移, 导致相应的RR带有较大的强度. 非全对称的B_1g和B_2g 模式通过B项机理增强,其强度比A_1g模式小1～2个量级,与实验结果定性符合. 与实验相比,υ10模式(B_1g)RR强度的理论值过小,而υ11模式(B_1g)的理论值偏大;这可能是由于TOP²⁺的B-态(S₂态)具有Jahn-Teller效应.     

有限反常核

从一个相对论性核模型解得了有限反常核,并找到了两个临界质量数A₁=85和A₂=165,只当质量数A≥A₁时才存在束缚的反常核,当A≥A₂时反常核的第核子结合能大于正常核.当A>3310时反常核由于库伦能而变得非束缚.     

SiO2分子的基态(X1A1)结构与分析势能函数

应用群论及原子分子反应静力学方法推导了SiO₂分子的电子态及其离解极限，采用B3P86方法，在6-311G^**水平上,优化出SiO₂基态分子稳定构型为单重态的C_2V构型，其平衡核间距R_e=R_Si—O=0.1587 nm,∠OSiO＝111.2°,能量为-440.4392 a.u..同时计算出基态的简正振动频率:对称伸缩振动频率ν(B₂)=945.4cm^-1，弯曲振动频率ν(A₁)=273.5 cm^-1和反对称伸缩振动频率ν(A₁)=1362.9cm^-1.在此基础上，使用多体项展式理论方法，导出了基态SiO₂分子的全空间解析势能函数，该势能函数准确再现了SiO₂(C_2V)平衡结构.     

SU(23)大统一模型

本文构造了一个SU(23)大统一模型,并以中间统一标度M_A为输入计算了大统一标度M_G的一些可能的值.在本模型中,重子数B在规范场和Higgs部分均守恒,因此并无质子衰变发生.我们还对能量在M_A处的规范玻色子按规范群SU(3)_c×SU(3)_L×U(1)_Y进行了分类.     

四-(叔丁基)-四氮杂卟啉金属配合物的振动光谱和DFT计算

测量了四-(叔丁基)-四氮杂卟啉金属配合物(MT(tBu)TAP,M=Cu, Co, Ni, Zn)的拉曼和红外光谱. 在B3LYP理论水平上计算了其基态结构和振动光谱,基于计算结果对观察到的拉曼谱带进行了详细的指认. 考察了拉曼和红外谱带频率变化与四氮杂卟啉环结构的关系. 随着环内核尺寸的减小,C_βC_β′伸缩振动(A_g)、C_αN_m反对称伸缩振动(A_g)、以及C_αN_m对称伸缩振动(B_g) 的频率线性地增加,其中后两者对环内核尺寸的变化更为敏感.     

GW/BSE级别下的非绝热动力学模拟揭示桥连化学键对调控酞菁锌-富勒烯给体-受体复合物激发态弛豫过程的重要作用

本文采用基于多体格林函数方法和Bethe-Salpeter方程(GW/BSE)的电子结构计算方法和非绝热动力学模拟研究了两种不同桥连化学键构型(5-6构型和6-6构型)的酞菁锌-富勒烯(ZnPc-C₆₀)给受体复合物的激发态性质及其弛豫过程. 对于6-6构型,ZnPc-C₆₀的最低激发态S₁态为光谱明态,即ZnPc的局域激发(LE)态,因此,6-6构型的ZnPc-C₆₀在光激发之后几乎不会发生电荷分离过程. 相比之下,5-6构型的ZnPc-C₆₀的S₁态是C₆₀的LE态,为光谱暗态,而作为光谱明态的ZnPc的LE态的能量更高. 而且,在ZnPc和C₆₀的LE态之间还存在若干电荷转移(CT)态. 因此,电荷转移会在从高能的ZnPc的LE态到低能的C₆₀的LE态的弛豫过程中发生. GW/BSE级别的非绝热动力学模拟结果进一步验证了电子结构计算的结论,并给出了相关过程的时间尺度：从ZnPc到C₆₀的超快激发态能量转移过程在前200 fs完成;随后发生的是由C₆₀到ZnPc的超快空穴转移过程. 本工作表明不同的桥连化学键模式(即5-6和6-6构型)可用于调节ZnPc-C₆₀给体-受体复合物的激发态性质及其光电性质. 与此同时,本工作证明了GW/BSE级别的非绝热动力学方法是探索非周期性给体-受体复合物、有机金属配合物、量子点、纳米团簇等复杂体系的光诱导动力学的可靠工具.     

超核Λ5He的核结构研究及其结合能计算

对超核Λ5He的核结构及其对Λ超子结合能BΛ的影响进行了系统的研究.考察了其壳心核4He的极化效应,计算了当⁴He中含有D态混合成分时对结合能B_Λ的贡献.结果表明,壳心核受到Λ超子相互作用的严重极化,不再具有自由α粒子的结构;D态成分的贡献仅改善B_Λ的计算值约0.5MeV.进一步考察了可能的三集团结构,发现对Λ+d+d三集团模型,计算所得B_Λ值比较接近实验值,表明它有一定的合理性.要得到肯定的结论,有待进一步的研究.     

Adiabatic conversion of ultracold atoms to A<Subscript>3</Subscript>B-type tetrameric molecules

We investigate the conversion of ultracold bosonic atoms to heteronuclear tetramer A₃B by an Efimov resonance-assisted stimulated Raman adiabatic passage scheme. In view of recent experiments involving heteronuclear Efimov trimers KKRb and KRbRb [Phys. Rev. Lett. 103, 043201 (2009)], the intermediate state populated by heteronuclear trimer A₂B in the conversion process is considered. The atom-molecule dark state solution for a system with a population imbalance is derived analytically, and the role played by the imbalance in the conversion is studied. In addition, the effects of the external field parameters (including photoassociated pulse intensity, width, magnetic coupling strength and its detuning) on the conversion are discussed via the concept of adiabatic fidelity.     

Supersymmetric Isospectral Formalism for the Calculation of Near-Zero Energy States: Application to the Very Weakly Bound 4He Trimer Excited State

We propose a novel mathematical approach for the calculation of near-zero energy states by solving potentials which are isospectral with the original one. For any potential, families of strictly isospectral potentials (with very different shape) having desirable and adjustable features are generated by supersymmetric isospectral formalism. The near-zero energy Efimov state in the original potential is effectively trapped in the deep well of the isospectral family and facilitates more accurate calculation of the Efimov state. Application to the first excited state in ⁴He trimer is presented.     

Efimov states in asymmetric three-body atomic clusters

The work is devoted to the investigation of the weakly bound three-body atomic clusters. The calculations on the van der Waals trimer ⁷Li⁴He₂ are carried out using the differential Faddeev equations, which allows us to give accurate binding energies for both the ground and the exited state of the system. The results obtained indicate the Efimov nature of the excited state in this system.     

Use of supersymmetric isospectral formalism to realistic quantum many-body problems

We propose a novel mathematical approach for the calculation of resonances in weakly bound systems. For any potential, families of strictly isospectral potentials (with very different shape) having desirable and adjustable features can be generated. For systems having no bound ground state, an isospectral potential with a bound state in the continuum is possible. The quasi-bound state in the original shallow potential will be effectively trapped in the deep well of the isospectral family, facilitating more accurate calculation of resonance energy. Application to ⁶He, ⁶Li and ⁶Be yield excellent results. Another application is the calculation of Efimov states in weakly bound threebody system. We present the result of ⁴He trimer, where the first excited state is claimed to be an Efimov state.     

Are there Efimov trimers in hexafluorobenzene rather than in benzene vapor itself?

Is there a spectroscopic method to detect an Efimov state? Following our proposal of an Efimov state arising from three pseudo bosons (generalized Cooper pairs) in benzene, our spectroscopic studies have found no evidence of Efimov trimers (ET) in h₆- or d₆-benzene. However, hexafluoro-benzene has shown peaks that we attributed to ET and the pseudo bosons. The experimental evidence suggests that benzene pseudo bosons and subsequently ET are quite sensitive to the surroundings.     

Rotational effect on the thermodynamic properties of isotopes

It is shown that the differences in the thermodynamic properties of HT and D₂ is due to the fact that, for the same total mass, the distribution of mass between the two atoms is not the same. This fact introduces for the heteronuclear molecules a correlation between translational and rotational degrees of freedom. This is a pure quantal effect. A quantum-mechanical perturbation calculation shows that the energy of the ground state is higher for assemblies of heteronuclear molecules than for assemblies of homonuclear ones. On account of this the equation of state of heteronuclear hydrogen molecules is different from that of homonuclear hydrogen molecules. This permits an understanding, for example, of the higher vapour pressure of HT compared to D₂ and the anomalous behaviour of HD.     

How to study the elusive efimov state of the 4He3 molecule through a new atom-optical state-selection technique

Excited states and excitation energies of weakly bound systems, e.g., atomic few-body systems and clusters, are difficult to study experimentally. For this purpose we propose a new and very general atom-optical method which is based on inelastic diffraction from transmission gratings. The technique is applicable to the recently found helium trimer molecule 4He3, allowing for the first time an investigation of the possible existence of an excited trimer state and determination of its excitation energy. This would be of fundamental importance for the famous Efimov effect.     

Influence of H-bond chains in solvents on the solubility of inert substances. A new quantitative approach.

The classic thermodynamic treatments considering self-associated liquids A as multicomponent systems are unable to explain the solubilities of substances B in these liquids by effects directly related to the presence of H-bond chains. This is not the case when the hypothesis of successive equilibria between the i-mers is abandoned and replaced by a single equilibrium between bonded and free hydroxylic protons. In the new treatment presented here two combinatorial entropies are considered : that resulting from the exchange possibilities between bonded and non-bonded protons and that originating from the exchange between A and B molecules. For large values of φ_A, the volume fraction of the associated liquid, it is shown that the latter combinatorial entropy is practically equal to that calculated in absence of self-association. The fraction γ of the free hydroxylic protons depends on the molar enthalpy of the hydrogen bond ΔH_h and on the entropy of chain-reintegration ΔS_h. The latter depends on the formal concentration F_A of the associated substance and a quantitative treatment shows that dΔS_h/dlnF_A = R (gas constant). This conclusion is experimentally confirmed by the variation of the vapor pressure with F_A in the series of the primary alcohols. The introduction of an inert substance B causes F_A to decrease and enhances the lowering of the entropy of the bonded molecules with respect to the non-bonded molecules. This creates a hydrophobic effect that is at the origin of the lowering of the solubility φ_B of B in A. As a consequence, lnφ_B at the equilibrium is diminished by an amount equal to b_Aφ_A$\text{V}$_B/$\text{V}$_A, where $\text{V}$_B and $\text{V}$_A are the formal molar volumes of both substances. b_A is a so called “structuration factor” of the solvent A that nearly equals ?1 for strongly associated solvents with single H-bond chains, like alcohols, and ?2 for solvents with double chains like water. Taking for the combinatorial entropy between A and B an expression intermediate between the classic one in mole fractions and that of Flory-Huggins in volume fractions, one derives equations that predict the solubility of alkanes in water and in alcohols. Although these equations do not contain any adjustable parameter and that the experimental solubilities φ_B cover several orders or magnitude, the agreement between prediction and experiment is remarkable.     

Spectroscopic characterization and potential energy functions of the six low-lying electronic states of ArKr+

Pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron spectra of ArKr have been recorded in the wavenumber range 108,000–118,000 cm^?1 using a 1 + 1′ two-photon resonant excitation scheme from the ground X 0⁺ state of ArKr via selected intermediate states located just below the Ar(¹S₀) + Kr([5p[1/2]₀) dissociation limit. The positions of ionic vibrational levels with quantum numbers from 1 to 30, from 0 to 8 and from 0 to 6 were determined for the X(1/2), A₁(3/2) and A₂(1/2) states, respectively. The assignment of absolute vibrational quantum numbers of the ionic states was derived from the isotopic shifts of the spectral lines. Combining these data with literature data on the B(1/2) → X(1/2), C₁(3/2) → A₁(3/2) and C₂(1/2) → A₂(1/2) band systems of ArKr⁺ enabled the derivation of potential energy functions for the lowest six electronic states of ArKr⁺ using a global potential model that includes the effects of the spin-orbit, charge-exchange and long-range interactions.     

A modified thermodynamic perturbation theory of Wertheim for heteronuclear molecules

The Wertheim thermodynamic perturbation theory (TPT1) is modified for fluids of heteronuclear molecules. The equation proposed by Mansoori–Carnahan–Starling and Leland has been applied for monomers instead of the Carnahan–Starling equation. The modified TPT is compared with simulation results and other theoretical results for heteronuclear dimer, trimer, and higher mers covering a wide range of size ratios. The modified TPT gives a useful method of extending the original TPT1 model to molecules of heteronuclear hard sphere cores without introducing any parameter such as shape factor α.