Laser-induced Fluorescence Spectroscopy of NiCl in 12900-15000 cm-1

Laser-induced fluorescence excitation spectra of jet-cooled NiCl molecules were recorded in the energy range of 12900-15000 cm^-1. Six vibronic bands with rotational structure have been observed and assigned to the [13.0]²П^3/2(v'=0-5)-X²П^3/2(v"=0) transition progres-sion. The relevant rotational constants, significant isotopic shifts, and (equilibrium) molecu-lar parameters have been determined. In addition, the lifetimes of the observed bands have also been measured.     

Infrarotspektroskopische untersuchungen an metallcupferronaten im bereich 4000-32 cm-1

The preparation and empirical interpretation of the m.i.r. and f.i.r. spectra of the cupferronates of Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Sn²⁺, Pb²⁺ und Bi³⁺ in the range 4000—32 cm^-1 is described. The bands in the range 1700—500 cm^-1 and the C—H valency vibrations can be assigned to vibrations of the pure ligand; differentiation of individual metal chelates in this range is therefore difficult. In contrast, the far i.r. region (below 500 cm^-1) contains many absorption bands (the metal chelate fingerprint region) which differ in position and intensity. The position of the bands with the highest v—M—O character, which can be recognised on the basis of the large metal-dependent frequency shifts, depends linearly on the second ionization potential of the metal atom, except for the Mn and Sn chelates. The relative absorptions, E_M—O/E, of the far i.r. bands of these cupferronates allow classification of the chelates into groups corresponding to the metal—ligand bonding involved (tetrahedral, octahedral and planar). The characteristic value used for this classification (the quotient of the absorption at the M—0 frequency and the absorbance of the strongest remaining band in the far i.r.) covers the range 0.92–2.17 for tetrahedral chelates, and 5.30–6.20 for planar chelates, with the octahedrally coordinated chelates having intermediate values.     

Analysis of the LIF Spectroscopy of Nickel Hydride in 19000-21400 cm-1

The laser-induced fluorescence (LIF) excitation spectrum of NiH was recorded in the spectral region from 15000 cm-1 to 21400 cm-1, with the NiH molecules produced by the reaction of sputtered nickel atoms with methanol under supersonic jet conditions. The 19000-21400 cm-1 portion of the spectrum of NiH is reported for the first time. Twenty-four bands were observed and classified into seven electronic transitions. Every band was rotationally analyzed. Higher vibrational levels of many excited states, A, B, D, E, F, and G,were observed and the complete set of spectroscopic parameters, vibrational frequency, unharmonic constant, rotational constant, and equilibrium length of these states were obtained. Some bands were reassigned     

U+与CO2气相反应的密度泛函理论研究

运用密度泛函理论(DFT)中的B3LYP方法,U原子用含相对论有效原子实势(ECP)校正的基组(SDD),C、O原子采用6-311+G(d)基组,对气相中U+和CO2的反应进行了理论研究.通过研究二重和四重自旋态的反应势能面(PESs),优化得到了两条反应路径的反应物、中间体、过渡态和产物的结构.用"两态反应"(TSR)分析反应机理,结果表明体系的优先选择路径为高自旋态进入和低自旋态离开反应,发生在四重态和二重态的自旋多重度的改变使得整个反应系统能以一个低能反应途径进行.     

Full-Dimensional Potential Energy Surfaces of Ground (\begin{document}${\tilde X^2}$\end{document}A') and Excited (\begin{document}${\tilde{A}^2}$\end{document}A") Electronic States of HCO and Absorption Spectrum

In this work, high-fidelity full-dimensional potential energy surfaces (PESs) of the ground (\begin{document}$\tilde X^2$\end{document}A\begin{document}$'$\end{document}) and first doublet excited (\begin{document}$\tilde A^2$\end{document}A\begin{document}$"$\end{document}) electronic states of HCO were constructed using neural network method. In total, 4624 high-level ab initio points have been used which were calculated at Davidson corrected internally contracted MRCI-F12 level of theory with a quite large basis set (ACV5Z) without any scaling scheme. Compared with the results obtained from the scaled PESs of Ndengué et al., the absorption spectrum based on our PESs has slightly larger intensity, and the peak positions are shifted to smaller energy for dozens of wavenumbers. It is indicated that the scaling of potential energy may make some unpredictable difference on the dynamical results. However, the resonance energies based on those scaled PESs are slightly closer to the current available experimental values than ours. Nevertheless, the unscaled high-level PESs developed in this work might provide a platform for further experimental and theoretical photodissociation and collisional dynamic studies for HCO system.     

Investigations on adiabatic potential energy curve of Li2()

The SAC-CI method is used to investigate the spectroscopic properties of ⁷Li₂(). The adiabatic potential energy curves are calculated and fitted to the analytic Murrell–Sorbie function. The spectroscopic parameters reproduced by the potential attained at cc-PVTZ are found to be very close to the experiments. With the potential obtained at the SAC-CI/cc-PVTZ level of theory, a total of 62 vibrational states is found when J = 0. For each vibrational state, the vibrational level, classical turning points, inertial rotation and centrifugal distortion constants are calculated. Good agreement is obtained when they are compared with the available RKR data.     

BH分子X 1Σ+、A 1Π和B 1Σ+ 态的势能函数

利用SAC/SAC-CI方法，使用D95++、6-311++g及cc-PVTZ等基组，对BH分子的基态(X ¹Σ⁺)、第一简并激发态(A ¹Π)及第二激发态(B ¹Σ⁺)的平衡结构和谐振频率进行了优化计算． 通过对三个基组计算结果的比较，得出了cc-PVTZ基组为三个基组中的最优基组的结论；使用cc-PVTZ基组，利用SAC的GSUM(group sum of operators)方法对基态(X ¹Σ⁺)， SAC-CI的GSUM方法对激发态(A ¹Π 和B ¹Σ⁺)进行单点能扫描计算, 用正规方程组拟合Murrell-Sorbie函数，得到了相应电子态的完整势能函数；从得到的势能函数计算了与基态(X ¹Σ⁺)、第一简并的激发态(A ¹Π)和第二激发态(X ¹Σ⁺)相对应的光谱常数(Be、αe、ωe 和ωeχe)，结果与实验数据较为一致． 其中基态、第一激发态与实验数据吻合得较好．     

BF分子X1Σ＋, A1P和B1Σ＋态的势能函数

使用SAC/SAC-CI和D95＋＋, 6-311＋＋g, 6-311＋＋g**及D95(d)基组, 分别对BF分子的基态X¹Σ^＋、第一简并激发态A¹Π和第二激发态B¹Σ^＋的平衡结构和谐振频率进行优化计算. 对所有计算结果进行比较, 得出6-311＋＋g**基组为最优基组. 运用6-311＋＋g**基组和SAC方法对基态X¹Σ^＋, SAC-CI方法对激发态A¹Π和B¹Σ^＋进行单点能扫描计算, 并用正规方程组拟合Murrell-Sorbie函数, 得到相应电子态的势能函数解析式, 由得到的势能函数计算了与X¹Σ^＋, A¹Π和B¹Σ^＋态相对应的光谱常数, 结果与实验数据较为一致.     

Molecular-beam-laser studies of the states X1Σ+ and A0+ of PbS

By using a molecular-beam apparatus, laser excitation spectra and microwave-optical double-resonance spectra were observed on the electronic states X¹Σ⁺ and A0⁺ of PbS. For the microwave spectra a resolution up to 10 kHz was achieved and microwave two-photon transitions could be detected. All information was combined into single fitting routine including data from other sources. Besides the usual Dunham parameters the fit model takes account of the breakdown of the Born-Oppenheimer approximation and the isotopic field shift. From the field shift of the electronic energy, the vibrational motion and the rotational motion the electron density as a function of the internuclear distance at the Pb nucleus is derived, which allows a more detailed discussion of the electronic structure of the molecule in combination with future quantum-chemical calculations. Additionally it is shown that the variation of the electron density along the vibrational motion at low vibrational levels can be as large as the variation for the electronic transition A0⁺ -X¹Σ⁺ in the case of PbS. The magnetic hyperfine structure of ²⁰⁷Pb is resolved in a molecule for the first time. The coupling parameter of PbS is compared with that of the isovalent molecule TlCl.     

The laser-induced fluorescence spectrum of CoS between 15 200 and 19 000 cm-1

Laser-induced fluorescence excitation spectra of jet-cooled CoS molecules have been recordedin the energy range of 15200～19000 cm^-1. Five transition progressions have been reportedfor the first time, the assignments of these progressions have been derived from a rotationalanalysis of vibronic bands and they are determined to be [15.58]⁴Δ_7/2～X⁴Δ_7/2, [16.02]⁴Δ_7/2～X⁴Δ_7/2, [16.50]⁴Δ_7/2～X⁴Δ_7/2, [17.80]⁴П_5/2～X⁴Δ_7/2, and [18.00]⁴Δ_7/2～X⁴Δ_7/2transitions. In addition, under the supersonic jet condition the fluorescent lifetimes of these vibronic states were measured by exponentially fitting the fluorescence decay. Based on the observed spectra and the measured lifetimes of the vibronic states, the newly identified electronic states are discussed.     

Theoretical Investigations on Photodissociation Dynamics of Deuterated Alkyl Halides CD3CH2F

The product branching ratio between different products in multichannel reactions is as important as the overall rate of reaction, both in terms of practical applications (\emph{e.g}. models of combustion or atmosphere chemistry) in understanding the fundamental mechanisms of such chemical reactions. A global ground state potential energy surface for the dissociation reaction of deuterated alkyl halide CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F was computed at the CCSD(T)/CBS//B3LYP/aug-cc-pVDZ level of theory for all species. The decomposition of CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F is controversial concerning C\begin{document}$ - $\end{document}F bond dissociation reaction and molecular (HF, DF, H\begin{document}$ _2 $\end{document}, D\begin{document}$ _2 $\end{document}, HD) elimination reaction. Rice-Ramsperger-Kassel-Marcus (RRKM) calculations were applied to compute the rate constants for individual reaction steps and the relative product branching ratios for the dissociation products were calculated using the steady-state approach. At the different energies studied, the RRKM method predicts that the main channel for DF or HF elimination from 1, 2-elimination of CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F is through a four-center transition state, whereas D\begin{document}$ _2 $\end{document} or H\begin{document}$ _2 $\end{document} elimination from 1, 1-elimination of CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F occurs through a direct three-center elimination. At 266, 248, and 193 nm photodissociation, the main product CD\begin{document}$ _2 $\end{document}CH\begin{document}$ _2 $\end{document}+DF branching ratios are computed to be 96.57%, 91.47%, and 48.52%, respectively; however, at 157 nm photodissociation, the product branching ratio is computed to be 16.11%. Based on these transition state structures and energies, the following photodissociation mechanisms are suggested: at 266, 248, 193 nm, CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F\begin{document}$ \rightarrow $\end{document}absorption of a photon\begin{document}$ \rightarrow $\end{document}TS5\begin{document}$ \rightarrow $\end{document}the formation of the major product CD\begin{document}$ _2 $\end{document}CH\begin{document}$ _2 $\end{document}+DF; at 157 nm, CD\begin{document}$ _3 $\end{document}CH\begin{document}$ _2 $\end{document}F\begin{document}$ \rightarrow $\end{document}absorption of a photon\begin{document}$ \rightarrow $\end{document}D/F interchange of TS1\begin{document}$ \rightarrow $\end{document}CDH\begin{document}$ _2 $\end{document}CDF\begin{document}$ \rightarrow $\end{document}H/F interchange of TS2\begin{document}$ \rightarrow $\end{document}CHD\begin{document}$ _2 $\end{document}CHDF\begin{document}$ \rightarrow $\end{document}the formation of the major product CHD\begin{document}$ _2 $\end{document}+CHDF.     

PdO0,±1, PdH0,±1及PdOH分子结构和电子性质的从头计算

利用多种从头计算方法对PdO0,±1, PdH0,±1以及PdOH的结构和电子性质进行了理论研究. 优化了PdO分子两个能量相近的态(3∏和3∑-), 结果表明PdO 的3∏态较3∑-态更为稳定, 在单双激发耦合簇理论(CCSD)水平下3∑-态的总能量比3∏态的高出0.286 eV. 在结构优化的基础上计算了PdO以及PdH的绝热电离能(AIE)和电子亲和能(AEA), 计算结果与实验值符合得很好. PdOH的基态为Cs对称性的角型结构Pd—OH(2A'态), 另外还优化得到两个2A'态的亚稳结构, 分别对应于Pd—OH和O—Pd—H, CCSD水平下两个亚稳态的总能量较基态分别高0.405和2.284 eV, 优化得到了连接这两个2A'态的过渡态, 并计算了相应的反应能垒.     

Laser-induced Fluorescence and Dispersed Fluorescence Spectroscopy of NiB: Identification of a New 2II State in 19000-22100 cm-1

The laser-induced fluorescence excitation spectra of jet-cooled NiB radicals have been recorded in the energy range of 19000-22100 cm^-1. Eleven bands have been assigned to the [20.77]²II-X²∑⁺ transition system for the first time. The dispersed fluorescence spectra related to most of these bands have been investigated. Vibrationally excited levels of the ground electronic state, with v" up to 6, have been observed. In addition, the lifetimes for almost all the observed bands have also been measured.     

Non-adiabatic collisions in H+ + O2 system: An ab initio study

An ab initio study on the low-lying potential energy surfaces of H⁺ + O₂ system for different orientations (γ) of H⁺ have been undertaken employing the multi-reference configuration interaction (MRCI) method and Dunning’s cc-pVTZ basis set to examine their role in influencing the collision dynamics. Nonadiabatic interactions have been analysed for the 2 × 2 case in two dimensions for γ = 0°, 45° and 90°, and the corresponding diabatic potential energy surfaces have been obtained using the diabatic wavefunctions and their CI coefficients. The characteristics of the collision dynamics have been analysed in terms of vibrational coupling matrix elements for both inelastic and charge transfer processes in the restricted geometries. The strengths of coupling matrix elements reflect the vibrational excitation patterns observed in the state-to-state beam experiments.     

超声波辅助测定I3-=I-+I2平衡常数实验的微型化

“测定I3-=I-+I2平衡常数”是大学无机化学实验课的实验之一,该实验中使用了较多的碘,分散振荡时间较长,导致残留的碘挥发到空气中给环境和人体带来危害。为此对该实验进行了改进,利用超声波辅助分散减少分散时间,用微量代替常量减少试剂用量。经过多次重复实验,在超声波辅助分散5 min,降低试剂用量90%的情况下,测得平衡常数为1.54×10-3,相对误差为2.67%,证明该方法完全可以替代现有的实验方法。     

A study of interaction in the lowest singlet and triplet states of H2

The potential energy curves of the ground state and the first excited state of H₂ are examined in terms of the electronic force acting on each nucleus. The results reveal the detailed course of events that occur when two hydrogen atoms with parallel and antiparallel electron spins approach one another from a large internuclear separation.     

Theoretical Study of Interaction Between S2 and SiHx (x=1, 2, 3) in Porous Silicon

The interaction between S₂ molecule and SiH_x (x=1, 2, 3) in porous silicon is investigated using the B3LYP method of density functional theory with the lanl2dz basis set. The model of porous silicon doped with CH₃,Si-O-Si and OH species is built. By analyzing the binding energy and electronic transfer, we conclude that the interaction of S₂ molecule with SiH_x (x=1, 2, 3) is much stronger than the interaction of S₂ molecule with CH₃ and OH, as S₂ molecule is located in different sites of the model. Using the transition state theory, we study the Si₂H₆+S2→H₃SiH₂SiS+HS reaction, and the reaction energy barrier is 50.2 kJ/mol, which indicates that the reaction is easy to occur.     

Ab initio quantum chemical studies of reaction mechanism for CH2CO with NCO

An extensive quantum chemical study of the potential energy surface (PES) for all possible isomerization and dissociation reactions of CH₂CO with NCO is reported at the DFT (B3LYP/6-311++G(d,p)) and CCSD(T)/cc-pVDZ//B3LYP/6-311++G(d,p) levels of theory. For the CH₂CO+NCO reaction, the formation of CO+CH₂NCO via an addition–elimination mechanism is the dominant channel on the doublet surface. While the formation of CO+CH₂OCN via bimolecular substitution reaction is in the secondary. Meanwhile, the isomerization and dissociation reactions of the products, CH₂NCO and CH₂OCN, also have been investigated using the same theoretical approach. It can be concluded that these reaction channels are not feasible kinetically at low or fairly high temperatures. On the basis of the ab initio data, the total rate constants for the CH₂CO+NCO reaction in the T=296–560 K range have been computed using conventional transition state theory with Wigner tunneling correction and fitted by a rate expression as k=2.14×10⁻¹² (cm³ molecule⁻¹ s⁻¹) exp(654.29/T). The calculated total rate constants with Wigner tunneling correction for the CH₂CO+NCO reaction are in good agreement with the available experimental values.     

Rotational cooling of Li 2 ( 1 S g + ) molecules by ultracold collisions with a helium gas buffer

The very weak interaction of Li₂ with He atoms has been obtained from accurate ab initio calculations and is here analyzed in terms of its anisotropic features. Quantum scattering calculations of the rotational inelastic de-excitation cross sections are carried out using a recently proposed multichannel treatment, the modified variable phase method, implemented by the authors and applied here to ultralow collision energies. General conclusions on the low efficiency of a He buffer gas in cooling down molecular rotations in this system are presented and analyzed.Proceedings of the 11th International Congress of Quantum Chemistry satellite meeting in honor of Jean-Louis Rivail.This work is affectionately dedicated to Prof. Jean-Louis Rivail on the occasion of his university retirement. We wish our friend many more happy years of research and the continued opportunity of guiding young scientists.     

碳纳米管膜分离Li+/Mg2+的分子动力学模拟

采用"扶手椅"型碳纳米管建立了连续的碳纳米管膜模型,利用分子动力学模拟方法研究了Li+和Mg2+在膜中的传导行为.模拟研究了不同管径的碳纳米管CNTs(7,7),(8,8),(9,9),(10,10),(11,11)对Li+和Mg2+的通透性,检测了两种离子进入管内时的平均力势,探索了两种离子在碳纳米管内的径向、轴向密度分布,观测了个别离子在管内的运动轨迹.结果表明,模拟中CNTs(9,9)用于有效分离Li+和Mg2+的效果较好.管径不同,导致Li+和Mg2+通量不同,平均力势(PMF)差值不同,同时离子的轨迹和径向、轴向密度分布也有所差异.总之,碳纳米管是一种可将Li+和Mg2+分离的潜在材料.