用微扰增强双共振对Na2 2 3 Πg和 3 3 Πg能级进行新观测

The Ω = 0,1,2 levels of the Na2 2 3Πg and 3 3Πg states in the energy region between 34860 cm-1 above the Te of the ground state and the 3s+3d atomic limit have been probed by pulsed laser perturbation facilitated optical-optical double resonance（PFOODR）spectroscopy. Strong mixing of these two states has been observed. The Tv and Bv values are given for the Ω = 0 component without deperturbation.     

非线形CS2 分子单重态和三重态的密度泛函理论

The geometrical optimizations on nonlinear CS2 in the singlet and triplet states have been made using two Density Function Theory（DFT）methods（B3LYP and B3PW91）with 6-311+G* and aug-cc-pVTZ basis sets. Three Singlet states 1A1 and five triplet states（3A2、3B1 and 3B2）have been found,and the frequency analysis confirms that there are no image frequencies for these states,indicating that they are geniune minima at the potential energy surface. At their respective equilibrium geometries,the lowest-lying electronic states are predicted to have an energy ordering by 4t 3B2相似文献   

稀土配合物（RE（DBM）3，RE=Nd、Sm、Gd）分子内能量弛豫过程的光声光谱研究

利用光声振幅谱和位相谱对稀土配合物(Nd(DBM)3、 Sm(DBM)3和Gd(DBM)3分子内弛豫过程进行了研究。Sm(DBM)3、 Gd(DBM)3和Nd(DBM)3的配体π-π*跃迁的光声振幅强度依次增强,而Gd、 Sm和Nd的配合物在配体吸收波段内位相依次减小,反映分子内的弛豫过程。对于Gd(DBM)3,配体最低三重态能量不能传递到中心离子4f激发态能级上而直接弛豫回基态;对于Sm(DBM)3和Nd(DBM)3,配体三重态能量有效地传递到中心离子上, Nd3+各能级间隔小且相互重叠,激发态能量几乎全部以无辐射跃迁回基态; Sm3+为荧光离子,激发态上的部分能量以荧光形式发射。由此并结合荧光光谱的结果建立了分子内能量弛豫模型。     

CH3 CH2 +N(4S)反应机理的理论研究

The reaction for CH3CH2+N(4S) was studied by ab initio method. The geometries of the reactants, intermediates, transition states and products were optimized at MP2/6-311+G(d,p) level. The corresponding vibration frequencies were calculated at the same level. The single point calculations for all the stationary points were carried out at the QCISD(T)/ 6-311+G(d,p) level using the MP2/6-311+G(d,p) optimized geometries. The results of the theoretical study indicate that the major products are the CH2CH2+3NH and H2CN＋CH3, and the minor products are the CH3CHN+H in the reaction. The majority of the products CH2CH2+3NH are formed via a direct hydrogen abstraction channel. The products H2CN＋CH3 are produced via an addition/dissociation channel. The products CH3CHN+H are produced via an addition/dissociation channel.     

Charge-Transfer and Spin-Flip States: Thriving as Complements

Transition metal complexes with photoactive charge-transfer excited states are pervasive throughout the literature. In particular, [Ru(bpy)₃]²⁺ (bpy=2,2′-bipyridine), with its metal-to-ligand charge-transfer emission, has been established as a key complex. Meanwhile, interest in so-called spin-flip metal-centered states has risen dramatically after the molecular ruby [Cr(ddpd)₂]³⁺ (ddpd=N,N′-dimethyl-N,N′-dipyridin-2-yl-pyridine-2,6-diamine) led to design principles to access strong, long-lived emission from photostable chromium(III) complexes. This Review contrasts the properties of emissive charge-transfer and spin-flip states by using [Ru(bpy)₃]²⁺ and [Cr(ddpd)₂]³⁺ as prototypical examples. We discuss the relevant excited states, the tunability of their energy and lifetimes, and their response to external stimuli. Finally, we identify strengths and weaknesses of charge-transfer and spin-flip states in applications such as photocatalysis and circularly polarized luminescence.     

Electronic states of SnS and SnS+: a configuration interaction study

Ab initio based multireference configuration interaction calculations are carried out for SnS and its monopositive ion using effective core potentials. Potential energy curves and spectroscopic constants of the low-lying states of SnS and SnS+ are computed. The ground-state dissociation energies of the neutral and ionic species are about 4.71 and 2.86 eV, respectively which compare well with the available thermochemical data. The effect of d-electron correlation on the spectroscopic constants of a few low-lying states has been studied. The spin-orbit interaction has also been included to investigate its effect on the spectroscopic properties of both SnS and SnS+. Dipole moment and transition moment curves are also constructed as a function of the bond length. Transition probabilities of some dipole-allowed and spin-forbidden transitions are studied. Radiative lifetimes of a few low-lying states are estimated. The E1sigma+-X1sigma+ transition of SnS is predicted to be the strongest one. The components of the A2sigma(+)(1/2)-X2(2)pi(1/2) transition with parallel and perpendicular polarization are separately analyzed. The vertical ionization energies of the ground-state SnS to the ground and low-lying excited states of the monopositive ion are calculated.     

β 沸石中铝的状态及归属

The states of aluminum in zeolites β were investigated with FTIR spectroscopy. Three kinds of aluminium, framework, nonframework and transient state aluminium, were detected in template-removed zeolite β. The states of aluminium in our samples strongly depends on the nature of the compensating cation, consistent with Brougeat-Lami et al's conclusion. But some new assignments of aluminum species and new opinions about the states of aluminum and their transformation are proposed. From the experimental results, we suggest that, the distortion and tension of zeolite lattice occur when protons, which possess high electron affinity , are located at cationic sites, leading to the breakage of Al-- O bond and the removal of aluminium. The distortion is released when H+ is replaced by other cations (e.g. Na+ ) so that transient state aluminium can go back into the framework, while the cationic nonframework aluminium species enter the solution upon the ion-exchange.     

Reaction Mechanism of the Multi-channel Decomposition Reactions of C_(10)H_(14)~+·

n-Butylbenzene cations C10H14^＋ serve as a model compound to investigate the reaction mechanisms of alkylbenzene cations. The reactions of C10H14^＋. decomposition reaction system have been studied extensively at the B3LYP/6-311＋＋G^＊＊ level with Gaussion98 package. The chain reaction of C10H14^＋ dissociation was initiated by C-H bond rupture. All reaction channels initiated by C-H rupture were fully investigated with the vibrational mode analvsis to confirm the transition states and to reveal the reaction mechanism. A theoretical investigation on the reactions of this positive ion free radical can help us fully understand the decomposition processes.     

CH3CH2+O(3P)反应机理的理论研究

The reaction for CH3CH2+O(3P) was studied by ab initio method. The geometries of the reactants, intermediates, transition states and products were optimized at MP2/6-311+G(d,p) level. The corresponding vibration frequencies were calculated at the same level. The single-point calculations for all the stationary points were carried out at the QCISD(T)/6-311+G(d,p) level using the MP2/6-311+G(d,p) optimized geometries. The results of the theoretical study indicate that the major products are the CH2O＋CH3, CH3CHO+H and CH2CH2+OH in the reaction. For the products CH2O＋CH3 and CH3CHO+H, the major production channels are A1: (R)→IM1→TS3→(A) and B1: (R)→IM1→TS4→(B), respectively. The majority of the products CH2CH2+OH are formed via the direct abstraction channels C1 and C2: (R)→TS1(TS2)→(C). In addition, the results suggest that the barrier heights to form the CO reaction channels are very high, so the CO is not a major product in the reaction.     

锂分子里德堡态和双激发态的重新分类

根据里德堡轨道的类氢nλ特性,对 7Li2实验已观测到的和理论计算给出的68个电子态进行了分类,把这些态划分为核实贯穿里德堡态和核实非贯穿里德堡态.讨论了双电子激发态和里德堡态的微扰,也讨论了这种分类的意义.     

2,5-Dioxido-1,4-benzoquinonediimine (H2L2-), a hydrogen-bonding noninnocent bridging ligand related to aminated topaquinone: different oxidation state distributions in complexes [{(bpy)2Ru}2(mu-H2L)]n (n=0,+,2+,3+,4+) and [{(acac)2Ru}2(mu-H2L)]m (m=2-,-,0,+,2+)

The symmetrically dinuclear title compounds were isolated as diamagnetic [(bpy)2Ru(mu-H2L)Ru(bpy)2](ClO4)2 (1-(ClO4)2) and as paramagnetic [(acac)2Ru(mu-H2L)Ru(acac)2] (2) complexes (bpy=2,2'-bipyridine; acac- = acetylacetonate = 2,4-pentanedionato; H2L = 2,5-dioxido-1,4-benzoquinonediimine). The crystal structure of 22 H2O reveals an intricate hydrogen-bonding network: Two symmetry-related molecules 2 are closely connected through two NH(H2L2-)O(acac-) interactions, while the oxygen atoms of H2L2- of two such pairs are bridged by an (H2O)8 cluster at half-occupancy. The cluster consists of cyclic (H2O)6 arrangements with the remaining two exo-H2O molecules connecting two opposite sides of the cyclo-(H2O)6 cluster, and oxido oxygen atoms forming hydrogen bonds with the molecules of 2. Weak antiferromagnetic coupling of the two ruthenium(III) centers in 2 was established by using SQUID magnetometry and EPR spectroscopy. Geometry optimization by means of DFT calculations was carried out for 1(2+) and 2 in their singlet and triplet ground states, respectively. The nature of low-energy electronic transitions was explored by using time-dependent DFT methods. Five redox states were reversibly accessible for each of the complexes; all odd-electron intermediates exhibit comproportionation constants K(c)>10(8). UV-visible-NIR spectroelectrochemistry and EPR spectroscopy of the electrogenerated paramagnetic intermediates were used to ascertain the oxidation-state distribution. In general, the complexes 1n+ prefer the ruthenium(II) configuration with electron transfer occurring largely at the bridging ligand (mu-H2Ln-), as evident from radical-type EPR spectra for 13+ and (+. Higher metal oxidation states (iii, iv) appear to be favored by the complexes 2m; intense long-wavelength absorption bands and RuIII-type EPR signals suggest mixed-valent dimetal configurations of the paramagnetic intermediates 2+ and 2-.     

C2(a 3Πu)+NO的反应机理研究

The reaction mechanism of C2（a 3Πu）+ NO is investigated at the level of G2（CC,MP2）. The equilibrium geometries,harmonic frequencies and energy of various stationary points on the potential energy surfaces have been calculated in the lowest doublet states. It is found that there are two reaction mechanisms:one is CCON mechanism that begins from O atom of NO attacks C2 and the intermediate is CCON;the other is called CCNO mechanism for its intermediate is CCNO formed by N atom of NO attacks C2 . In the same time,the five possible ground product pathways corresponding to these two mechanisms for this reaction are analysed and concluded that the pathway that O atom of NO attacks C2 to produce the major products CN+CO via CCNO mechanism is the most favorable pathway.     

Mechanism of cysteine oxidation by a hydroxyl radical: a theoretical study.

Cysteine oxidation by HO(.) was studied at a high level of ab initio theory in both gas phase and aqueous solution. Potential energy surface scans in the gas phase performed for the model system methanethiol+HO(.) indicate that the reactants can form two intermediate states: a sulfur-oxygen adduct and a hydrogen bound reactant complex. However these states appear to play a minor role in the reaction mechanism as long as they are fast dissociating states. Thus the main reaction channel predicted at the QCISD(T)/6-311+G(2df,2pd) level of theory is the direct hydrogen atom abstraction. The reaction mechanism is not perturbed by solvation which was found to induce only small variations in the Gibbs free energy of different reactant configurations. The larger size reactant system cysteine+HO* was treated by the integrated molecular orbital+molecular orbital (IMOMO) hybrid method mixing the QCISD(T)/6-311+G(2df,2pd) and the UMP2/6-311+G(d,p) levels of theory. The calculated potential energy, enthalpy, and Gibbs free energy barriers are slightly different from those of methanethiol. The method gave a rate constant for cysteine oxidation in aqueous solution, k=2.4 x 10(9) mol(-1) dm(3) s(-1), which is in good agreement with the experimental rate constant. Further analysis showed that the reaction is not very sensitive to hydrogen bonding and electrical polarity of the molecular environment.     

Ab initio study on the ground and low-lying excited states of cesium iodide (CsI)

Potential energy curves (PECs) for the ground and low-lying excited states of the cesium iodide (CsI) molecule have been calculated using the internally contracted multireference configuration interaction calculation with single and double excitation method with the relativistic pseudopotentials. PECs for seven Lambda-S states, X 1Sigma+, 2 1Sigma+, 3Sigma+, 1Pi, and 3Pi are first calculated and then those for 13 Omega states are obtained by diagonalizing the matrix of the electronic Hamiltonian H(el) plus the effective one-electron spin-orbit (SO) Hamiltonian H(SO). Spectroscopic constants for the calculated ground X 0+-state PEC with the Davidson correction are found to agree well with the experiment. Transition dipole moments (TDMs) between X 0 and the other Omega states are also obtained and the TDM between X 0+ and A 0+ is predicted to be the largest and that between X 0+ and B 0+ is the second largest around the equilibrium internuclear distance. The TDMs between X 0+ and the Omega=1 states are estimated to be nonzero, but they are notably small as compared with those between the 0+ states. Finally, vibrational levels of the X 0+ PEC for the two isotopic analogs, (133)CsI and (135)CsI, are numerically obtained to investigate the isotope effect on the vibrational-level shift. It has been found that the maximized available isotope shift is approximately 30 cm(-1) around nu=136.     

Ein Neues gemischtvalentes Oxoosmat(VI,VII): Sr11Os26+Os27+O24

A New Mixed Valenced Oxoosmate(VI, VII): Sr₁₁Os₂⁶⁺Os₂⁷⁺O₂₄ . Single crystals of Sr₁₁Os₂⁶⁺Os₂⁷⁺O₂₄ were prepared in closed silver bombs using SrO, osmium and an extend of KO₂. It crystallizes with monoclinic symmetry, space group C–I12/a1 a = 11.703; b = 16.058; c = 11.696 Å; β = 90.03°; Z = 4. Sr₁₁Os₂⁶⁺Os₂⁷⁺O₂₄ shows a new crystal structure characterized by a [Sr₁₁O₂₄]^26? network and incorporated Os⁶⁺ and Os⁷⁺ ions. Calculations of the coulombterm of lattice energy shows an orderer distribution of the two oxidation states of osmium.     

态-态热力学函数及其应用 I: 双分子交换反应

本文把Levine的态-态热力学函数由振动-振动态推广到振转-振转态, 对A+BC(v, j)→AB(v', j')+C双分子交换反应给出了Gibbs自由能△G^o(v, j→v',j', T)和化学平均常数K(v, j→v', j', T)在谐振子-截锥转子模型下的详细计算公式, 对H+O2(v, j)→HO(v', j')+O作了数值计算, 结果与由实验归纳出的定性规律相符合。利用本文给出的公式不仅可以对化学反应过程描述得更加细致和深刻, 而且可以方便地讨论分子的振动-转动态耦合对化学反应性的影响。     

Investigation of Structures and Stabilities of AlmPn and AlmP(m+n=2～6)Clusters by DFT

The geometries,electronic states and energies of Alm Pn （ m + n = 2 ～ 6）neutral and anionic clusters have been investigated using the density functional theory（DFT）method of Becke’s three-parameter hybrid exchange functional with the nonlocal correlation of B3LYP. Structural optimization and frequency analyses are performed with the basis of 6-311G（ d）. The calculations predict the existence of a number of previously unknown isomers（i. e. ,Al3P_ and AlmPn （ m + n.5））. The calculations have also predicted that small AlP and（AlP）2 clusters adopt two-and three-dimensional structures characteristic of Si2 and Si4 clusters,while the structures of the larger AlP clusters are different completely from those of Sin clusters with the same electrons. The results show that the structures with the singlet have higher symmetries,while those with the doublet have lower symmetries. The vertical detachment energy of AlmPn （ m + n = 2 ～ 6）are also discused and the adiabatic electron affinities of AlmPn（m + n = 2 ～ 6）and also discussed at the same level. The results agree satisfactorily with the anion photoelectron spectroscopy of aluminum phosphide clusters reported recently by Gomez et al.     

SiH3+O(3P)反应机理的理论研究

The reaction for SiH3+O(3P) was studied by ab initio method. The geometries of the reactants, intermediates, transition states and products were optimized at MP2/6-311+G(d,p) level. The single point calculations for all the stationary points were carried out at the QCISD(T) /6-311+G(d,p) level using the MP2/6-311+G(d,p) optimized geometries. The results of the theoretical study indicate that the major pathway is the SiH3+O(3P)→IM1→TS3→IM2→TS8→HOSi+H2. The other minor products include the HSiOH+H, H2SiO+H and HSiO+H2. Furthermore, the products HOSi, HSiO and HSiOH(cis) can undergo dissociation into the product SiO. In addition, the calculations provide a possible interpretation for disagreement about the mechanism of the reaction SiH4+O(3P). It suggests that the products HSiOH, H2SiO and SiO observed by Withnall and Andrews are produced from the secondary reaction SiH3+O(3P) and not from the reaction SiH4+O(3P).     

Electronic spectra of linear isoelectronic clusters C2n+1S and C2n+1Cl+ (n = 0-4): an ab initio study

Structures and stabilities of linear carbon chains C2n+1S and C2n+1Cl+ (n=0-4) in their ground states have been investigated by the CCSD and B3LYP approaches. The CASSCF calculations have been used to determine geometries of selected excited states of both isoelectronic series. Linear C2n+1S cluster has a cumulenic carbon framework, whereas its isoelectronic C2n+1Cl+ has a dominant character of acetylenic structure in the vicinity of terminal Cl. The vertical excitation energies of low-lying excited states have been calculated by the CASPT2 method. Calculations show that the excitation energies have nonlinear size dependence. The 2(1)Sigma+<--X1Sigma+ transition energy in C2n+1S has a limit of 1.78 eV, as the chain size is long enough. The predicted vertical excitation energies for relatively strong 1(1)Pi<--X1Sigma+ and 2(1)Sigma+<--X1Sigma+ transitions are in reasonable agreement with available experimental values. The spin-orbit effect on the spin-forbidden transition in both series is generally small, and the enhancement of the spin-forbidden transition by spin-orbit coupling exhibits geometrical and electronic structural dependence.     

The state-to-state-to-state model for direct chemical reactions: application to D+H2-->HD+H

A simple theoretical model is developed to predict the state-to-state dynamics of direct chemical reactions. Motivated by traditional ideas from transition state theory, expressions are derived for the reactive S matrix that may be computed using the local transition state dynamics. The key approximation involves the use of quantum bottleneck states to represent the near separable dynamics taking place near the transition state. Explicit expressions for the S matrix are obtained using a Franck-Condon treatment for the inelastic coupling between internal states of the collision complex. It is demonstrated that the energetic thresholds for various initial reagent states of the D+H(2) reaction can be understood in terms of our theory. Specifically, the helicity of the reagent states are found to correlate directly to the symmetry of the quantum bottleneck states, which thus possess very different thresholds. Furthermore, the rotational product state distributions for D+H(2) are found to be associated with interfering pathways through the quantum bottleneck states.