氮分子{a'^1}\Sigma _g^ (v' = 0)和{a'^1}\Sigma _g^ + (v' = 1) + {b^1}\Pi _u(v' = 0) 广义振子强度的高能电子散射研究

利用快电子能量损失谱仪结合相对流量技术,在入射电子能量1500 eV和能量分辨70 meV的条件下,测量了氮分子{a''^1}\Sigma _g^ (v'' = 0)和{a''^1}\Sigma _g^ + (v'' = 1) + {b^1}\Pi _u(v'' = 0)激发态的广义振子强度。通过与已有的电子散射结果以及X射线散射结果对比发现,对于{a''^1}\Sigma _g^ (v'' = 0)和{a''^1}\Sigma _g^ + (v'' = 1) + {b^1}\Pi _u(v'' = 0),我们的结果与X射线散射结果在大动量转移出现差异,这表明对{a''^1}\Sigma _g^ (v'' = 0)和{a''^1}\Sigma _g^ (v'' = 1),即使入射电子能量1500 eV也没有达到一阶玻恩近似条件。在动量转移平方小于2 a.u.时, {a''^1}\Sigma _g^ + (v'' = 1) + {b^1}\Pi _u(v'' = 0)与X射线散射结果的符合表明,对{b^1}\Pi _u(v'' = 0),1500 eV入射电子能量已经达到一阶玻恩近似条件。     

Absorption spectra and isotope shifts of the(2, 0),(3, 1), and(8, 5) bands of the A~2Π_u-X~2Σ_g~+ system of ~(15)N_2~+ in near infrared

The high-resolution absorption spectra of the(2, 0),(3, 1), and(8, 5) bands of the A~2Π_u–X~2Σ_g~+system of~(15) N_2~+ have been recorded by using velocity modulation spectroscopy technique in the near infrared region. The rotational constants of the X~2Σ_g~+and A~2Π_u states of~(15) N_2~+ were derived from the spectroscopic data. The isotope shifts of these bands of the A~2Π_u–X~2Σ_g~+system of~(14) N_2~+ and~(15) N_2~+ were also analyzed and discussed.     

F22分子6a′, 4a″和3a″轨道的电子动量谱研究

在1 200 eV入射能量下测量了F22分子轨道6a′, 4a″和3a″的电子动量谱, 并与用Hartree-Fock和密度泛函方法选取不同基组的理论计算结果进行了比较.     

Spectroscopic investigations on NO~+(X~1Σ~+, a~3Σ~+, A~1Π) ion using multi-reference configuration interaction method and correlation-consistent sextuple basis set augmented with diffuse functions

Three low-lying electronic states (X1Σ+, a3Σ+, and A1Π) of NO+ ion are studied using the complete active space self-consistent-field (CASSCF) method followed by highly accurate valence internally contracted multi-reference configuration interaction (MRCI) approach in combination of the correlation-consistent sextuple basis set augmented with diffuse functions, aug-cc-pV6Z. The potential energy curves (PECs) of the NO+(X1Σ+, a3Σ+, A1Π) are calculated. Based on the PECs, the spectroscopic parameters Re, De, ωe, ωeχe, αe, Be, and D0 are reproduced, which are in excellent agreement with the available measurements. By numerically solving the radial Schrdinger equation of nuclear motion using the Numerov method, the first 20 vibrational levels, inertial rotation and centrifugal distortion constants of NO+(X1Σ+, a3Σ+, A1Π) ion are derived when the rotational quantum number J is equal to zero (J = 0) for the first time, which accord well with the available measurements. Finally, the analytical potential energy functions of these states are fitted, which are used to accurately derive the first 20 classical turning points when J = 0. These results are compared in detail with those of previous investigations reported in the literature.     

Ar气对~(39)K_2分子C~1Ⅱ_u→X~1∑_g~+LIF光谱的碰撞猝灭效应

实验测量了缓冲气体Ar气对~(39)K_2分子C~1Π_u(v′=O,J′=53)→X~1∑_g~+(v″=5,6,J″=52,54)LIF光谱的碰撞猝灭效应.用稳态碰撞模型推导出LIF光谱强度I对气体压强P=P_(Ar)+P_K的函数关系.用上述模型拟合出的I-P曲线和实验数据的符合,对拟合所得参数C_1的进一步分析指出:热管炉后向探测LIF光谱方法比非增益荧光探测法的灵敏度可提高2倍以上.     

基于3~3Σ_1~+共振耦合态制备超冷基态~(85)Rb~(133)Cs分子的实验研究

本文3~3Σ_1~+以为中间激发态,通过扫描光缔合光的频率得到了3~3Σ_1~+的不同振动态光谱。研究发现利用短程光缔合制备的超冷基态~(85)Rb~(133)Cs分子产率在3~3Σ_1~+(v=3)处较其他振动态更大,3~3Σ_1~+(v=3)转动常数较邻近的振动态有明显变化且与2~3Π_(0-)(v=14)的能量接近,这些特征显示了这两个振动态的共振耦合特性。优化光缔合光的功率和光电离光的能量后,我们得到X~1Σ~+(v=0)最低振动态超冷~(85)Rb~(133)Cs分子的产率为1.5×10~4/s。在考虑了分子波函数的宇称和跃迁选择定则后,我们发现3~3Σ_1~+(v=3,J=1)存在单步自发辐射制备超冷基态~(85)Rb~(133)Cs分子的通道,采用该通道可实现原子-分子相干转移直接制备超冷基态分子。     

Cs(6D5/2)+H2→CsH[ X1Σ+(v,J)]+H转动分辨总截面的测量

利用泵浦-检测方法,在样品池条件下,研究了Cs(6D5/2)与H2反应碰撞传能过程。利用激光感应荧光（LIF）光谱技术,确定了CsH[X1Σ+(v,J)]振转能级上的布居分布,转动态分布与热统计分布基本一致.Cs激发态原子密度由激光能量吸收得到.记录A1Σ+(v',J+1)→X1Σ+(v,J)的时间分辨荧光,从荧光强度的对数值给出的直线斜率确定(v',J+1)→(v,J)的自然辐射率,结合(v,J)→(v',J+1)吸收系数的测量,得到反应生成物CsH[X1Σ+(v,J)]态的分子密度.由速率方程分析,给出反应截面(v,J),对J求和,得到(v)[10-16cm2单位]分别为（0.64±0.19）（v=0）和（0.58±0.17）（v=1）.     

State-to-state dynamics of F(~2P) + HO(~2Π) → O(~3P) + HF(~1Σ~+)reaction on 1~3A〞 potential energy surface

State-to-state time-dependent quantum dynamics calculations are carried out to study F(~2P) + HO(~2Π) → O(~3P) +HF(~1Σ~+) reaction on 1~3A〞 ground potential energy surface(PES). The vibrationally resolved reaction probabilities and the total integral cross section agree well with the previous results. Due to the heavy–light–heavy(HLH) system and the large exoergicity, the obvious vibrational inversion is found in a state-resolved integral cross section. The total differential cross section is found to be forward–backward scattering biased with strong oscillations at energy lower than a threshold of 0.10 eV, which is the indication of the indirect complex-forming mechanism. When the collision energy increases to greater than 0.10 eV, the angular distribution of the product becomes a strong forward scattering, and almost all the products are distributed at θ_t = 0°. This forward-peaked distribution can be attributed to the larger J partial waves and the property of the F atom itself, which make this reaction a direct abstraction process. The state-resolved differential cross sections are basically forward-backward symmetric for v' = 0, 1, and 2 at a collision energy of 0.07 eV; for a collision energy of 0.30 eV,it changes from backward/sideward scattering to forward peaked as v increasing from 0 to 3. These results indicate that the contribution of differential cross sections with more highly vibrational excited states to the total differential cross sections is principal, which further verifies the vibrational inversion in the products.     

基于ab initio的BD~+离子激光冷却理论研究

基于相关一致基组aug-cc-pV5Z,采用内收缩多参考组态相互作用方法计算了BD~+离子两个最低解离极限B~+(~1Sg)+D(~2Sg)和B+(~3Pu)+D(~2Sg)对应的5个Λ—S态(X~2Σ~+,A~2Π,B~2Σ+,a~4Π和b~4Σ~+)的势能曲线和跃迁偶极矩.根据计算结果,求解核运动的径向薛定谔方程得到相应电子态的振-转光谱常数、Franck-Condon(F-C)因子和振动能级辐射寿命.其中A~2Π—X~2Σ~+的F-C因子(f_(00)=0.923)、辐射寿命(τ=235 ns)满足激光直接冷却的条件.因此,我们基于分子转动跃迁提出了一个可实现Doppler激光冷却的光循环方案:A~2Π_(1/2)(υ′=0)—X~2Σ+(υ′′=0,1),其中υ′=0中包含2个转动能级,υ′′=0和υ′′=1中分别包含6个和4个转动能级.根据方案,模拟了激光冷却过程中的分子布居数动力学变化过程,并计算了初速度为100 m/s的BD~+,历经5.4 ms散射1150个光子可减速到4.6 m/s、温度为13 mK.     

环戊酮分子8a1轨道的电子动量谱学研究

首次获得了环戊酮分子8a1轨道的电子动量谱的实验结果，并且给出了价轨道的电离能谱信息．实验用非共面对称几何条件下的能量多道型电子动量谱仪完成，入射电子的能量为1200 eV和600 eV加结合能．Hatree-Fock方法和密度泛函理论计算得到的结果与实验结果作了比较，实验结果和理论计算符合较好．     

自由基CH(X2Π,a4Σ-)的光谱数据从头算研究

用分子轨道从头算方法,对CH自由基的基态(X2Π)和低激发态(a4Σ-)的光谱数据进行了计算.计算结果表明,在基态CH(X2Π)时,在QCISD(T)/6-311G (3df,3pd)水平上,计算所得的键长R=0.1120981nm,偶极矩μ＝1.5891 Debye,ν＝2845.43cm-1均与实验值相吻合,在B3PW91/6-311G (3df,3pd)理论水平上,计算的基态能量为-38.496143 Hartree,误差仅为0.22%;对低激发态CH(a4Σ-),使用含时的密度泛函方法(TDDFT)和大基组6-311 G(3df,3pd)计算所得的R=0.1094nm,垂直跃迁能量为0.926eV,均与实验结果有较好的吻合.     

环戊酮分子8a1轨道的电子动量谱学研究

首次获得了环戊酮分子8a1轨道的电子动量谱的实验结果,并且给出了价轨道的电离能谱信息.实验用非共面对称几何条件下的能量多道型电子动量谱仪完成,入射电子的能量为1200 eV和600 eV加结合能.Hatree-Fock方法和密度泛函理论计算得到的结果与实验结果作了比较,实验结果和理论计算符合较好.     

CS21B2(1Σ+u)态预离解产物CS的振转布居研究

用一束波长为 2 10 .2 7nm的激光将CS2 分子激发至预离解态1B2 (1Σ+ u) ,用另一束激光通过激光诱导荧光 (LIF)方法检测碎片CS ,在 2 5 0 .5～ 2 86 .5nm获得了CS碎片A1Π←X1Σ+ 振转分辨的激发谱 .通过对光谱强度的分析 ,获得了CS碎片v″ =0～ 8的振动布居和v″=1,4～ 8振动态的转动布居 .结果发现 ,碎片CS的振动布居呈双模结构 ,分别对应于CS2 分子1B2 (1Σ+ u)态的两个解离通道 ,即CS(X1Σ+ ,v″=0～ 9) +S(3 PJ)和CS(X1Σ+ ,v″ =0～ 1)+S(1B2 ) .由此得到两个解离通道的分支比S(3 PJ) :S(1B2 )为 5 .6± 1.2 .与前人 193nm处的研究结果相比 ,2 10 .2 7nm激发更有利于S(3 PJ)通道的生成 .此外 ,实验还发现CS的转动布居不满足热平衡分布 ,为两个Boltzmann分布的合成     

氨分子在0_0~0和2_0~1带的选择光离解

本文利用脉冲紫外激光(UV)选择激发氨分子到A~1A″_2电子激发态的两个最低振动能级υ′_2=0和υ′_2=1(ν_2振动),然后检测新生态H原子的飞行谱(TOF),研究了氨分子的光碎片动力学。光谱证实了最近所测的离解能D_0~0(H-NH_2)=4.645eV;绝大多数生成的NH_2(X~2B_1)基处于非振动激发,但是具有围绕a惯性轴的高度转动激发。通过NH_3(A)的υ′_2=1光离解产生的NH_2(X)基具有较高的内部激发,并且显示了在N=K_a转动能级上的反转布居。     

氧分子的价壳层光学振子强度研究

在入射电子能量为1500eV、平均散射角为0°、能量分辨为60meV条件下，得到了氧分子在5.7—28.5eV能量区间的光学振子强度密度谱，获得了氧分子E³Σ^-_ｕ的ν′=0，1，2和2³Π_ｕ的ν′=0，1各振动能级的绝对光学振子强度，同时检验了我们的Bethe-Born转换因子外推到低能端的可靠性．将所得结果与前人的工作进行了比     

~(39)K_2分子C~1Ⅱ_u-X~1∑_9~+(J′=105)Q支激光诱导荧光光谱及电偶极跃迁矩变化率研究

用4415.6(?)CW激光线获得了~(39)K_2分子C~1II_u(v′=0,J′=105)-X~1∑_g~+(v″=1～10,J″=105)Q支激光诱导荧光(LIF)光谱.用最小二乘法拟合出了~(39)K_2分子X~1∑_g~+态振动常数和C~1II_u态电子谱项值T_e.光谱分析表明C~1II_u态T_e=22968cm~(-1)是合适的.用~(39)K_2分子Morse势计算了(V′=0,J′=105)-(v″=1～10,J″=105)跃迁的Franck-Condon因子和跃迁强度,强度计算值和激光诱导荧光光谱测量值之间有令人满意的符合,进一步的r重心近似分析给出了~(39)K_2分子C~1II_u→X~1∑_g~+电偶极跃迁矩R_(?)随核间距r的归一化变化率为-0.157～-0.168 debye/(?)(4.22(?)相似文献   

CS_2~+经由~2Σ_u~+←~2Π_(g,3/2)跃迁的[1+1]光倒空和光碎片激发谱(英文)

用483.2nm的电离激光使CS2分子经由[3+1]REMPI制备出CS2+(X~2Πg,3/2)后,在270~285nm扫描解离激光获得了CS2+经由~B2Σu+←X~2Πg,3/2跃迁的光倒空和光碎片激发谱,由此给出了CS2+~B2Σu+电子态的振动频率ν1=613cm-1和2ν2=707cm-1.分析表明,正是CS2+的[1+1]双光子光激发解离过程导致了母体离子CS2+的光倒空和光解离成碎片离子CS+和S+,该过程中光碎片离子的分支比CS+/S+大约为3.     

Product polarization and mechanism of Li + HF(v=0, j=0) → LiF(v', j') + H collision reaction

A state-to-state dynamics analysis for the Li+HF(v=0,j=0)→LiF(v',j')+H collision reaction has been performed through quasiclassical trajectory(QCT)calculations.It is found that the differential cross section(DCS)of the LiF products from the title reaction is preferentially backward scattering for v=0,yet forward scattering for v=1 and 2.For v=3,the DCS exhibits forward,backward,and sideways scatterings.The variation of the internuclear distances and angles along the propagation time reveals that more than 99.08%of reaction trajectories undergo the direct reaction mechanism.The values of the polarization parameters a{1}1and a{2}0demonstrate that the product rotational angular moment j' is not only aligned perpendicular to the reagent relative velocity vector,but also oriented along the negative y axis.These product polarization results agree well with the recent quantum mechanical studies.The mechanism of these results was proposed and discussed in detail.     

OCS分子在128nm附近的光解动力学研究:S(~3P_(J=2,1,0))、S(~1D_2)以及S(~1S_0)产物通道（英文）

本文利用时间切片离子成像技术对OCS分子进行了真空紫外波段的光解动力学研究.在四个光解光波长(从129.32到126.08 nm)下测量了硫原子解离产物S(~3P_J=2,1,0)、S(~1D_2)、S(_1S_0)的速度影像,并从中清晰地发现了四个主要的解离产物通道:S(~3P_(J=2,1,0))+CO(X~1∑~+),S(~3P_(J=2,1,0))+CO(A~3Π),S(~1D_2)+CO(X~1∑~+)和S(~1S_0)+CO(X~1∑~+).在实验影像中,产物CO分子的部分振动态结构能够得到分辨.实验还获取解离产物总平动能谱,产物分支比和角分布.对实验结果进行分析显示除绝热解离通道S(~3P_(J=2,1,0))+CO(A~3Π)之外,在共他三个产物通道中非绝热效应都起到非常重要的作用.     

交叉分子束实验研究F+D_2(v=1,j=0)反应（英文）

本文使用交叉分子束方法研究了氟原子和振动激发态氖分子D_2(v=1,j=0)的反应.使用受激拉曼抽运的方法制备了振动激发的D_2分子.实验中未观测到来自于旋轨耦合激发态氟原子F*(~2P_(1/2))与振动激发态D_2分子的贡献.观测到来自于旋轨耦合基态氟原子F(~2P_(3/2))和振动激发态D_2的反应信号,相应的产物DF分子布居于u'=2,3,4,5振动态上.与振动基态反应F+D_2(v=1,j=0)相比,振动激发态反应F+D_2(v=1,j=0)生成的DF产物转动分布更"热".获得了振动激发反应的四个碰撞能在0.32至2.62 kcal/mol范围内的微分反应截面.在最低的碰撞能0.32 kcal/mol下,所有振动态的DF产物都以后向散射为主.随着碰撞能的增加,DF产物的角分布逐渐从后向转移到侧向.测量了DF(v'=5)产物的前向微分散射截面随碰撞能变化的曲线.前向散射的DF(v'=5)信号出现于1.0 kcal/mol.在2.62 kcal/mol碰撞能下DF(v'=5)主要为前向散射.