NaLi分子飞秒含时光电子能谱的理论研究

运用三态模型和含时波包方法,研究了NaLi分子处于强飞秒抽运-探测激光场中的波包动力学过程和时间分辨光电子能谱,并且揭示了飞秒激光脉冲参数与NaLi分子光电子能谱之间的关系.研究发现:对于不同的激光波长,波包的振动周期是不同的,而且随着抽运-探测脉冲延迟时间的不同,NaLi分子光电子能谱的谱峰高度和位置发生变化;当λ1=352 nm并且?t=400 fs时,外阱中相应的光电离信号(0.5 eV处)明显强于内阱中相应的光电离信号(1.35 eV处).计算结果表明,NaLi分子激发态41Σ+上波包动力学的一些信息能够通过其光电子能谱反映出来.这些结果可以为实验上实现分子的光控制以及量子操控过程提供一些有价值的参考信息,并为进一步的理论研究提供重要依据.     

Study on wave packet dynamics of E~1Σ_g~+ state of Li_2 with femtosecond-resolved photoelectron spectra

Wave packet dynamics of the Li₂ molecule are investigated by using the time-dependent quantum wave packet method, and the time-resolved photoelectron spectra of the Li₂ molecule are calculated. The time-resolved wave packet theory is used to reasonably interpret the phenomena of the photoelectron spectra for different parameters. Our calculation shows that the loss of the wave packets in the shelf state area of E{ }^1\Sigma_g^ + plays a prominent role in the process of photoionization with the increase of the delay time. Moreover, the oscillation of the wave packet on the E{ }^1\Sigma_g^ + curve symbolizes a decreasing process of energy.     

Time-dependent wave packet theoretical study of femtosecond photoelectron spectra and coupling between the A<Superscript>2</Superscript>Σ<Superscript>+</Superscript> and B<Superscript>2</Superscript>Π states of the NO molecule in a strong laser field

In this work, the femtosecond time-resolved photoelectron spectra and the coupling between the A²Σ⁺ and B²Π states of the NO molecule in a strong laser field have been investigated by the time-dependent wave packet method. We demonstrate that the weak coupling between the A²Σ⁺ and B²Π states of NO plays a key role on the peak centered at 0.37 eV of the photoelectron spectra in the 2+1’ channel.     

Ab initio calculation of accurate dissociation energy, potential energy curve and dipole moment function for the A1∑ + state 7LiH molecule

The reasonable dissociation limit of the A¹∑⁺ state $^{7}$LiH molecule is obtained. The accurate dissociation energy and the equilibrium geometry of this state are calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space for the first time. The whole potential energy curve and the dipole moment function for theA¹∑⁺ state are calculated over a wide internuclear separation range from about 0.1 to 1.4\,nm. The calculated equilibrium geometry and dissociation energy of this potential energy curve are of R_{\e}=0.2487\,nm and D_{\e}=1.064\,eV, respectively. The unusual negative values of the anharmonicity constant and the vibration-rotational coupling constant are of \textit{\omega }_{\e}\textit{\chi }_{\e}=--4.7158cm^{ - 1} and \textit{\alpha }_{\e}=--0.08649cm^{ -1}, respectively. The vertical excitation energy from the ground to the A¹∑⁺ state is calculated and the value is of 3.613\,eV at 0.15875nm (the equilibrium position of the ground state). The highly anomalous shape of this potential energy curve, which is exceptionally flat over a wide radial range around the equilibrium position, is discussed in detail. The harmonic frequency value of 502.47cm¹ about this state is approximately estimated. Careful comparison of the theoretical determinations with those obtained by previous theories about the A¹∑⁺ state dissociation energy clearly shows that the present calculations are much closer to the experiments than previous theories, thus represents an improvement.     

The theoretical character of the X^1∑^＋ and A^1∑^＋ states of ScN

This paper calculates the potential energy curves (PECs) of the ground state (X 1 Σ + ) and excited state (A 1 Σ + ) of ScN molecule by multireference configuration interaction method. The correct character of the PECs has been gripped while they had been improperly reported in the literature. Based on the PECs, the spectroscopic parameters and vibrational energy levels are determined, and compared with experimental data and other theoretical works available at the present.     

Cl2分子Rydberg态及混合Rydberg-价态多光子光谱

本工作结合多光子离化谱,激光诱导荧光及荧光激发谱技术,仔细研究Cl₂分子高激发Rydberg态和混合Rydbery-价态的结构及性质,定域了1¹∑_u⁺态内区的位置,证明2¹∑_u⁺态强的Rydberg-价混合特征,发现一新的u对称性Rydberg态并建议标识为¹∑_u态的激发,对三光子激发过程,2^{1关键词：}     

Low-lying intrinsic energy levels in the nucleus170Ho

The band-head energies of the two-quasiparticle states expected in the doubly odd deformed nucleus¹⁷⁰Ho are calculated for a zero range residual interaction. The results are compared with the available experimental information. It is concluded that the ground state has the Nilsson configuration 6⁺{7/2^?[523↑] _p }+5/2[512↑] _n being the 2.76m isomer whereas the 43s isomer is the 1⁺ ∑=0 state arising from the same configuration and lies at about 100 keV excitation energy in agreement with the experiment. The first excited state in this nucleus is predicted to be the 4^?{3/2⁺[411↑] _p +5/2^?[521↑] _n } state close to the ground state with the corresponding 1^? ∑=0 member expected to appear well above the 1⁺ isomer.     

H2(X1∑g+)—H2(E1∑g+)系统的相互作用

采用显含电子对相关坐标的波函数,在微扰论的框架下计算了E^l∑_g⁺态氢分子与基态氢分子取cross构型时的中长程相互作用。结果表明,该相互作用在分子间距6.5α₀附近存在着一个活化能势垒,在4.5α₀附近显示出较强的化学键行为。 关键词：     

Time-dependent quantum wave packet and quasiclassical trajectory studies of the Au(2S) + H2(X1∑+g) → AuH(X1∑+g) + H(2S) reaction

The time-dependent quantum wave packet (TDWP) and quasiclassical trajectory calculations (QCT) are carried out for the Au(²S) + H₂(X¹∑⁺_g) → AuH(X¹∑⁺_g) + H(²S) reaction on a global potential energy surface. The reaction probabilities at a series of J values, integral cross sections (ICSs) and differential cross sections of the title reaction are calculated by the TDWP method. For reaction probabilities, there are a mass of sharp oscillations at low collision energy, which can be attributed to resonances supported by the potential well. Due to the endothermicity of the title reaction, the total ICS shows a threshold about 1.53 eV. In order to further investigate the reactive mechanism, the lifetime of complex is calculated by QCT method. At the low collision energy, most intermediate complexes are long lived, which implies that the reaction is governed by indirect reactive mechanism. With the collision energy increasing, the direct reactive mechanism occupies the dominant position. Due to the change of the reactive mechanism, the angular distribution shifts toward the forward direction with collision energy increasing. The isotopic variant, Au + D₂→AuD + D reaction, is also calculated by TDWP method. The calculated reaction probabilities and ICSs show that the isotope effect reduces the reactivity.     

Vibrational wave packet dynamics in the silver tetramer probed by NeNePo femtosecond pump-probe spectroscopy

We present results on the ultrafast dynamics of mass-selected neutral Ag₄ clusters using NeNePo (negative ion - neutral - positive ion) femtosecond pump-probe spectroscopy. One-color pump-probe spectra of the Ag₄ ^-/Ag₄/Ag₄ ⁺ system measured at 385 nm and an internal cluster temperature of 20 K display a complex beat structure over more than 60 ps. The oscillatory structure is attributed to vibrational wave packet dynamics in an excited “dark" state of neutral Ag₄. A dominant 740 fs wave packet period as well as wave packet dephasing and rephasing are observed in the spectra. Fourier analysis of the spectra yields a group of frequencies centered around 45 cm^-1 and an anharmonicity χ _e2νχ _eχ _e of 2.65 cm^-1 for the active vibrational mode. Received 30 November 2000     

用代数-能量自洽法研究双原子分子解析势能函数

基于计算双原子分子完全振动能谱及离解能的代数方法 (algebraic method,AM)和研究双原子分子解析势能函数的能量自洽法(energy consistent method,ECM),建立了计算双核分子体系精确解析势能函数的代数-能量自洽法(AM-ECM).应用AM-ECM方法研究了7Li+2-23Σg,KH-X1Σ+,NaLi-X1Σ+和NaLi-A1Σ+电子态的解析势能表达形式,并与其他方法的研究结果进行了比较,获得了能正确描述这些电子态在渐近区和离解区的精确解析表达结果.     

Theoretical Investigation of Femtosecond-Resolved Photoelectron Spectrum of NaI Molecules

The time-resolved photoelectron spectra （TRPES） of NaI molecules are calculated by using the time-dependent wave packet method. Two different potential energy curves （adiabatic and diabatic） are adopted in the simulation. The third peak of the photoelectron spectra presented in the adiabatic calculation is induced by the reflection of the wave packet. The oscillating of the wave packet onto the diabatic energy curve is a decreasing process. The comparison of the photoelectron spectra between the two different calculations （adiabatic and diabatic） is presented.     

On the Dissociation Energy of AsP Molecule

For the electronic ground state, X¹∑⁺, of AsP molecule, the true potential energy curve is constructed by the method of Rydberg-Klein-Rees. By curve fitting of the modified form of Lippincott's three-parameter empirical potential function, the dissociation energy is estimated to be 4.46±0.15 eV.     

Ar·CO团簇光电离的实验和理论研究

利用同步辐射光电离质谱装置,测量了Ar·CO范德瓦尔斯 (van der Waals, vdW) 团簇的的光电离质谱和光电离效率曲线.将它们与CO分子的绝对光吸收光谱比较, 发现在13.9到14.6 eV能量范围内的Ar·CO⁺的光电离效率曲线主要反映了收敛到 CO⁺ (X²∑⁺, v'= 1,2和3) Rydberg系列和收敛到 CO⁺ (A²Π)的n= 3的振动序列(v'= 6–9)的特点; 在14.6–15.75 eV光子能量范围内的Ar·CO的光电离效率曲线主要反映了CO的光吸收特性. 然而,由于Ar和CO之间的相互作用,其中的5个重要的光谱结构发生了蓝移; 而在15.75–15.80 eV光子能量范围内的Ar-CO的光电离效率曲线,它的属性受到组分Ar和CO的共同影响. 与此同时,也从理论上计算了Ar·CO团簇的电离能、Ar·CO团簇和Ar·CO⁺ 团簇离子的离解能. 关键词： Ar·CO团簇 同步辐射 光电离     

Spin-dependent and Coriolis interactions by an improved configuration interaction treatment: predissociation of excited fine structure levels of OH/OD

The state specific predissociation of OH/OD in its lowest electronically excited state (A²Σ⁺,v',N',F₁/F₂) is investigated by time dependent wave packet propagation techniques. To improve the accuracy of the potential energy curves, spin-orbit, spin-spin and rotational interactions required for the treatment, we have refined our CI techniques, using optimal orbitals for each of the electronic states. Potential energy curves, matrix elements and lifetimes of the rotational sublevels are compared with experiment and with theoretical values from multichannel scattering theory     

A shock tube determination of the CN ground state dissociation energy and the CN violet electronic transition moment

The CN ground state (X²∑⁺) dissociation energy and the electronic transition moment of the CN violet B²∑⁺ ? X²∑⁺ bands have been simultaneously determined from spectral emission measurements behind incident shock waves. The unshocked test gases were composed of various CO₂-CO-N₂-Ar mixtures, and the temperatures behind the incident shocks ranged from 3500 to 8000°K. The dissociation energy was determined to be 7.89 eV with a statistical precision of ±0.02 eV; a conservative estimate of the absolute error was ±0.13 eV. The value obtained for the Δυ = 0 sequence electronic transition moment was 0.90 ± 0.14, corresponding to an electronic absorption f-number of 0.035 ± 0.005 at a wavelength of 3860 Å. The electronic transition moment variation with internuclear separation was also measured.     

光学泵浦的锂分子激光

以可见染料激光泵浦锂分子,在高于900℃的蒸气温度下,获得了由理分子A¹∑_u⁺态跃迁到基态X¹∑_g⁺的位于874—912nm区的许多光泵激光输出。谐振腔使输出信号增强约9倍。对部分激光跃迁的振转量子数作了标识。 关键词：     

基于阈值光电子-光离子符合技术的分子离子光谱和解离动力学研究

对电子和离子同时采用速度聚焦电场收集的阈值光电子-光离子符合成像谱仪能够有效提高电子的收集效率和能量分辨率.利用该符合成像谱仪,开展了Xe/Ar/Ne 惰性混合气体及NO 分子的阈值光电子谱、阈值光电子-光离子符合质谱和质量选择的符合光谱等实验研究,精确测量了NO 分子的电离势,并且获得了NO⁺离子振动态分辨的X¹Σ⁺,c³Π和B^{1相似文献}   

Spectroscopic investigations on NO+(x1∑+,a3∑+,A1Ⅱ) ion using multi-reference configuration interaction method and correlation-consistent sextuple b

Three low-lying electronic states (x¹∑⁺,a³∑⁺,and A¹Ⅱ) 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⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) are calculated. Based on the PECs, the spectroscopic parameters R_e, D_e, ω_e, ω_eχ_e, α _e, B_e, and D₀ are reproduced, which are in excellent agreement with the available measurements. By numerically solving the radial Schrödinger equation of nuclear motion using the Numerov method, the first 20 vibrational levels, inertial rotation and centrifugal distortion constants of NO⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) 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.     

(e,2e) Spectroscopy of ethane

The 400-eV and 1200-eV non-coplanar symmetric (e, 2e) reaction has been used to measure the momentum distributions of electrons in the individual valence orbitals of ethane as well as to measure the complete separation energy spectra in the valence region. The shapes and relative magnitudes of the momentum distributions agree well with those calculated using the plane wave off-shell impulse approximation and double zeta basis molecular orbital wave functions. The ground state of C₂H₆⁺ is shown to be 1e_g^?1, with the vertical ionization potential being 12.25 ± 0.1 eV. Considerable structure due to configuration interaction is observed in the separation energy region 29–55 eV. Much of this structure can be assigned to the 2a_1g orbital.