磷基的几何结构与光电子能谱

基于ab initio/DFT理论,对磷基PH2分子X~2B1态和PH-2阴离子X~1A1态进行了几何结构优化和谐振频率计算.在B3LYP/6-311+G(2d,p)理论水平下,通过Franck-Condon因子计算模拟了PH-2实验的光电子能谱,计算得到的理论谱与实验谱完全一致,确认属于PH2(X~2B1)-PH-2(X~1A1)光脱附过程.另外,通过迭代Franck-Condon分析,得到优于ab initio/DFT理论计算的PH-2离子的几何结构参数R(PH)=0.1438±0.0002 nm和∠(HPH)=92.2±0.2°.     

二氧化铬阴离子光电子能谱的理论研究

凭借密度泛函理论,采用不同基组对中性分子CrO2的基态((X)3B1)以及阴离子CrO1-的基态((X)4B1)进行几何优化和振动频率分析;应用量化计算得到的力常数及结构和光谱参数,基于推得的两维四模Franck-Condon重叠积分的代数表示,对CrO2((X)3B1)-CrO2-((X)4B1)的光脱附过程进行Franck-Condon分析和光谱模拟,理论上得到光电子能谱的谱线相对强度及振动结构分布,理论谱与实验测得的二氧化铬阴离子光电子能谱达到一致,并对光电子能谱的振动结构进行归属及热带分析;另外,在光谱模拟过程中通过迭代Franck-Condon分析过程,推得CrO2-((X)4B1)与CrO2((X)3B1)平衡几何结构之差:△R(Cr-O)=0.05A,△∠(O-Cr-O)=12°.     

BCl分子X~1Σ~+,a~3Π和A~1Π态的光谱性质

采用Davidson修正的内收缩多参考组态相互作用方法(MRCI+Q)及Dunning等的相关一致基aug-ccpV6Z计算了BCl分子X1Σ+,a3Π和A1Π态的势能曲线.利用总能量外推公式,将这3个态的总能量分别外推至完全基组极限.对势能曲线进行核价相关修正及相对论修正计算,得到了同时考虑这两种修正的外推势能曲线.拟合势能曲线得到了3个态的主要光谱常数Te,Re,ωe,ωexe,Be,αe和De等,它们与已有的实验结果较为一致.利用获得的势能曲线,通过求解双原子分子核运动的径向Schrdinger方程,找到了BCl分子X1Σ+,a3Π和A1Π态的全部振动态,并得到了相应的振动能级和惯性转动常数等分子常数.还计算了a3Π—X1Σ+和A1Π—X1Σ+的跃迁偶极矩、Franck-Condon因子,预测了若干跃迁的辐射寿命.     

CF-2光电子能谱的Franck-Condon分析

在Born-Oppenheimer近似下,结合分子轨道从头算,采用谐振子模型和产生函数方法计算了CF2(X1A1)←CF-2(X2B1)跃迁的Franck-Condon因子.用迭代Franck-Condon分析(IFCA)方法对CF-2的光电子能谱进行了拟合,得到了基态CF-2的几何构型:r CF=0.142 9±0.000 1 nm,θFCF=101.10±0.01度.     

S3分子的构型与离解极限

在QCISD/6311 G水平上,优化出S3分子的稳定构型有C2v、D3h,且基态为C2v构型,属X1A1态,平衡核间距r12=1.94,键角∠321=117.2°,离解能为De=4.7668eV。并得到基态谐振频率ν1(a1)=574cm-1,ν2(a1)=265cm-1,ν3(b2)=646cm-1。同时用UMP2/6311 G方法算出S3分子可能的激发态有1A2,1B2,3A2,3B1和3B2。对硫灯的发光机理作了初步探讨     

AlH分子结构与分析势能函数

本文运用群论及原子分子反应静力学方法,推导了 AlH分子的基态(X1Σ+)、第一激发态(A1Π)及第三激发态(C1S+)的电子态及相应的离解极限.并使用SAC/SAC-CI方法,采用D95 (d)、6-311g(d)和cc-PVTZ等基组对AlH分子的基态(X1Σ+)、第一激发态(A1Π)和第三激发态(C1S+)的平衡结构和谐振频率进行了几何优化计算.通过对三个基组的计算结果与实验结果的比较,得到cc-PVTZ基组是三个基组中最优基组的结论.使用cc-PVTZ基组,对AlH 分子的基态(X1Σ+)、第一激发态(A1Π)和第三激发态(C1S+)进行了单点能扫描计算,并给出了AlH的基态(X1Σ+)、第一激发态(A1Π) 和第三激发态(C1S+)的Murrell-Sorbie函数形式的电子态的完整势能函数,进而得到了AlH分子第一激发态(A1Π)的激发能较小的结论.     

磷基的几何结构与光电子能谱

基于ab initio/DFT理论,对磷基分子以其阴离子态进行了几何结构优化和谐振频率计算。在B3LYP/6-311+G(2d,p)理论水平下,通过Franck-Condon因子计算模拟了磷基的光电子能谱[K. M. Ervin and W. C. Lineberger, J. Chem. Phys. 122 (2005) 194303],计算得到的理论谱与实验谱完全一致。另外,通过迭代Franck-Condon分析,得到优于ab initio/DFT理论计算的离子的几何结构参数。     

Determination of the anion O-3 geometry by Franck-Condon simulations of its photoelectron spectrum

A theoretical method to calculate multidimensional Franck-Condon factors including Duschinsky effects is described and used to simulate the photoelectron spectroscopy of the anion O-3. Geometry optimization and harmonic vibrational frequency calculations have been performed on the (X～)1A1 state of O3 and (X～)2B1 state of O-3. Franck-Condon analyses and spectral simulation were carried out on the first photoelectron band of O-3. The theoretical spectrum obtained by employing CCSD(T)/6-311+G(2d,p) values are in excellent agreement with the observed one. In addition, the equilibrium geometry parameters, re(OO)= 0.135 5±0.000 5 nm and θe(O-O-O) =114.5±0.5°, of the (X～)2B1 state of O-3, are derived by employing an iterative Franck-Condon analysis procedure in the spectral simulation.     

PdH、PdH2分子的结构与势能函数

用相对论有效原子实势(SDD)和密度泛函(B3LYP)方法对PdH和PdH2体系的结构进行了优化,计算表明:PdH分子的几何构型为C∞v,其基态为X2∑+态,键长R=0.154 11 nm,离解能为De=2.511 0eV,谐振频率ωe=2 156.226 9 cm-1,并拟合得到Murrell-Sorbie势能函数;PdH2分子稳态为C2y构型,电子组态为1A1,平衡核间距RPdH=0.151 73 nm,键角∠HPdH=72.373 3°,基态简正振动频率:对称伸缩振动频率v1(b2)=2 104.369 6 cm-1、弯曲振动频率v2(a1)=528.742 6 cm-1、反对称伸缩振动频率v3(a1)=2 208.649 0 cm-1,离解能De=5.318 56 eV.在此基础上,用Murrell-Sorbie函数和多体展式理论导出PdH(C∞v,X2∑+)、PdH2(C2v,1A1)分子的解析势能函数.其等值势能面图准确地再现了PdH2分子的结构特征和离解能,由此讨论了Pd+H2分子反应的势能面静态特征.     

二氧化铬阴离子光电子能谱的理论研究

凭借密度泛函理论,采用不同基组对中性分子CrO2的基态（ 3B1）以及阴离子CrO2‾的基态（ 4B 1）进行几何优化和振动频率分析;应用量化计算得到的力常数及结构和光谱参数,基于推得的两维四模Franck-Condon重叠积分的代数表示,对CrO2 ( 3B1)－CrO2‾ ( 4B1) 的光脱附过程进行Franck-Condon分析和光谱模拟,理论上得到光电子能谱的谱线相对强度及振动结构分布,理论谱与实验测得的二氧化铬阴离子光电子能谱达到一致,并对光电子能谱的振动结构进行归属及热带分析;另外,在光谱模拟过程中通过迭代Franck-Condon分析过程,推得CrO2‾（ 4B1）与CrO2（ 3B1）平衡几何结构之差：ΔR(Cr-O)= 0.05Å,Δ(O-Cr-O)=12o.     

S2O‾自由基光电子能谱的Franck-Condon分析

本文考虑多振动模混合和热带效应,凭借谐振子模型,推得计算两维-四振动模Franck-Condon重叠积分的解析表示,且应用于S2O‾ 自由基光电子能谱的理论研究。对于S2O( 1A′) – S2O‾( 2A″) 光脱附过程,结合分子轨道从头算和密度泛函理论,计算Franck-Condon因子,从而得到电子跃迁振动谱线的相对强度,理论上得到的光电子能谱与实验上观测到的能谱达到较好的一致;进一步在光谱模拟过程中,拟合实验能谱得到可靠的负离子自由基S2O‾电子态（ 2A″）的几何结构参数：键长R(SS) = 2.008 +/-0.005Å 和 R(SO) = 1.519+/-0.005Å.     

Experimental and Theoretical Study of the Electronic States and Spectra of TeH and TeLi

Gas-phase emission spectra of the hitherto unknown free radical TeLi have been measured in the NIR range with a Fourier-transform spectrometer. The emissions were observed from a fast flow system in which tellurium vapor in argon carrier gas was passed through a microwave discharge and mixed with lithium vapor in an observation tube. Two systems of blue-degraded bands were measured at high spectral resolution in the ranges 8000-9000 and 5700-6700 cm(-1) and vibrational and rotational analyses were performed. In order to aid in the analysis of the experimental data, a series of relativistic configuration interaction calculations has been carried out to obtain potential curves for the low-lying states of TeLi and the isovalent TeH and also electric dipole transition moments connecting them. As in the TeH system, the ground state of TeLi is found to be X(2)Pi(i), but with a remarkably smaller spin-orbit splitting. The TeLi calculations indicate a strongly bound A(2)Sigma(+) state, while in TeH the analogous state is computed to lie significantly higher at approximately 32 000 cm(-1), and it is strongly predissociated. Based on the theoretical analysis, the observed TeLi band systems are assigned to the transitions A(2)Sigma(+)(A1/2)-->X(1)(2)Pi(3/2)(X(1)3/2) and A(2)Sigma(+)(A1/2)-->X(2)(2)Pi(1/2)(X(2)1/2). Analysis of the spectra has yielded the molecular constants (in cm(-1)) X(1)(2)Pi(3/2):omega(e)=457.49(3), omega(e)x(e)=2.482(9), B(0)=0.408908(8); X(2)(2)Pi(1/2): T(e)=2353.44(3), omega(e)=456.28(4), omega(e)x(e)=2.635(8), B(0)=0.414954(8), p(0)=1.00637(4); A(2)Sigma(+): T(e)=8574.64(2), omega(e)=437.81(3), omega(e)x(e)=2.581(8), B(0)=0.423903(8), p(0)=-0.19915(2), where the numbers in parentheses are the standard deviations of the parameters. Comparison of the isovalent TeLi and TeH systems emphasizes that the difference in bonding character (ionic in TeLi vs covalent in TeH) is responsible for qualitative differences in the electronic spectra of these two molecules. Copyright 2001 Academic Press.     

NO通过C~2Π←X~2Π跃迁的共振多光子离化谱

以皮秒Nd∶YAG激光器抽运光学参变发生 /放大器做激发源 ,得到了NO分子在 4 90～ 5 80nm波长范围内通过C2 Π态共振增强的多光子离化谱 ,离化谱由有规则的谱线序列组成。将理论计算的峰值位置与实验结果进行比较 ,确定了离化通道为 :NO(X2 Π) 3hνNO(C2 Π) 2hν(orhν) NO+ +e ,离化信号强度随激光强度的近五次方变化关系进一步验证了此结论。分析讨论了谱线强度的分布不符合夫兰克康登原理的可能原因。根据谱线峰值位置 ,利用最小二乘法拟合获得NO分子C2 Π态振动常数′ωe=(2 35 4 .9± 6 .4 )cm-1,′ωe ′χe=(14 .7± 2 .5 )cm-1及平衡位置的力常数k=(2 .4 4± 0 .0 8)× 10 3 N·m-1。结果可为用激光离化光谱技术探测大气污染物NO分子提供参考。     

Evidence for a bound H dibaryon from lattice QCD

We present evidence for the existence of a bound H dibaryon, an I=0, J=0, s=-2 state with valence quark structure uuddss, at a pion mass of m(π)～389 MeV. Using the results of lattice QCD calculations performed on four ensembles of anisotropic clover gauge-field configurations, with spatial extents of L～2.0, 2.5, 3.0, and 3.9 fm at a spatial lattice spacing of b(s)～0.123 fm, we find an H dibaryon bound by B(∞)(H)=16.6±2.1±4.6 MeV at a pion mass of m(π)～389 MeV.     

激光冷却SH~–阴离子的理论研究

本文采用多组态相互作用及Davidson修正方法和全电子基组计算了SH~-阴离子的X~1∑~+,a~3∏和A~1∏态的势能曲线、电偶极矩和跃迁偶极矩.计算的光谱常数与实验值及已有的理论值符合得很好.在计算中考虑了自旋-轨道耦合效应.计算得到a~3∏_1(v'=0)?X~1∑_(0+)~+(v"=0)和A~1∏_1(v'=0)?X~1Σ_(0+)~+(v"=0)跃迁具有高对角分布的弗兰克-康登因子,分别为0.9990和0.9999;计算得到a~3∏_1和A~1∏_1态的自发辐射寿命分别为1.472和0.188 ms.A~1∏_1?X~1∑_(0+)~+跃迁存在中间态a~3∏_(0+)和a~3∏_1,但中间态对激光冷却SH~-阴离子的影响可以忽略.分别利用a~3∏_1(v'=0)? X~1∑_(0+)~+(v"=0)和A~1∏_1(v'=0)? X~1∑_(0+)~+(v"=0)跃迁构建了准闭合的能级系统,冷却所需的激光波长分别为492.27和478.57 nm.最后预测了激光冷却SH~-阴离子能达到的多普勒温度和反冲温度.这些结果为进一步实验提供了理论参数.     

Cs_2(B~1Π_u)态与基态Cs原子间的碰撞激发转移

在Cs2密度约为2×1013 cm-3的纯Cs样品池中,脉冲激光激发Cs2(X1 Σg+)至B 1Πu态,利用原子和分子荧光光谱方法研究了Cs2(B 1Πu)+Cs(6S)的碰撞激发转移过程.用736 nm激发Cs2到B 1Πu(v＜10),这时预解离不发生.由B 1Πu→X1 Σg+时间分辨跃迁信号得到B 1Πu态的辐射寿命为(35±7)ns,B1Πu态与Cs原子碰撞转移总截面为(4.0±0.5)×10-14 cm2.用705 nm激发至B 1Πu(v＞30)态,这时发生预解离,在不同的Cs密度下,测量了I(D1),I(D2)和分子带的时间积分荧光的相对强度,得到了预解离率为(4.3±1.7)×105 s-1(对预解离到6P3/2)和(4.7±1.9)×106 s-1(对预解离至6P1/2);碰撞转移截面为(0.45±0.18)×10-14 cm2(对转移到6 P1/2)和(4.3±1.7)×10-14 cm2(对转移到6P3/2).结果表明,如果B 1Πu(v)是束缚的,6P原子由碰撞转移产生;如果B 1Πu(v)是预解离的,则6P原子由预解离和碰撞转移产生.     

N2O+离子A2Σ+电子态的光解动力学研究

用一束波长为360.55nm的激光，通过N2O分子的（3+1）共振多光子电离（REMPI）过程制备纯净且布居完全处于X2Π(000)态的母体离子N2O+，然后用另一束波长在275—328nm范围内的可调谐激光将制备的N2O+离子激发至预解离电子态A2Σ+.实验发现，由于解离碎片NO+所具有的一定的反冲速度，其TOF质谱峰明显比N2O+母体宽.通过分析NO+碎片TOF质谱峰形状，得到了解离产物的总平均平动能〈ET〉；通过考察〈ET〉随光解能量的变化，发现光解能量在32000cm-1附近约250cm-1的变化 关键词： N2O+离子A2Σ+态 TOF质谱峰 预解离机理     

A High Resolution Study of the Shock Excited Spectrum of Yttrium Oxide

Abstract

The blue-green (B²? X²?) and orange (A²? –X²?) systems of yttrium oxide have been shock excited at temperatures of about 4000°K and photographed at high dispersion (～ 1.2Å/mm) in the first order of a 21 ft. grating spectrograph. The high dispersion shock excited spectra were recorded using multiple exposures and latensification of extremely high speed film. Over 50 new bands have been observed and assigned to specific vibrational transitions for the systems. New molecular constants have been derived from the A, B and X states. Provisional calculations have been made of Franck-Condon factors and r-centroids for the systems appropriate to new constants.