采用close coupling (CC)方法,在3A″势能面上[Guadagnini R,Schatz G C,Walch S P.Global potential energy surface for the lowest 1A′,3A″,and 1A″ states of HNO [J].J.Chem.Phys.,1995,10: 774],我们利用量子含时波包方法对N + OH的同位素反应-N+OD进行了研究.在0.0～0.8 eV的平动能范围内,选态的反应几率受共振结构支配.利用J-shifting方法计算,我们得到了基态的速率常数,并对分子间的同位素效应进行了研究.
In this paper,we theoretically investigate the effect of noise on the photoionization,the generation of the high-order harmonic and the attosecond pulse irradiated from a model He^+ ion.It shows that by properly adding noise fields,such as Gaussian white noise,random light or colored noise,both the ionization probabilities(IPs) and the harmonic yields can be enhanced by several orders of magnitude.Further,by tuning the noise intensity,a stochastic resonance-like curve is observed,showing the existence of an optimal noise in the ionization enhancement process.Finally,by superposing a properly selected harmonic,an intense attosecond pulse with a duration of 67 as is directly generated.
The above-threshold ionization of argon in an intense 70-fs,400-nm linearly polarized laser pulse has been investigated by the velocity map imaging techniques,combined with an attosecond-resolution quantum wave packet dynamics method.There is a quantitative agreement in all dominant features between the experiment and the theory.Moreover,a peak-splitting phenomenon in the first energy peak has been observed at high pulse intensity.Further,through the theoretical analysis,an ac Stark splitting with evident resonant and nonresonant ionization pathways has been found to be the physical reason for the experimental observations.
The stereodynamic properties of the F + HO(v,j) reaction are explored by quasi-classical trajectory(QCT) calculations performed on the 1A' and 3A' potential energy surfaces(PESs).Based on the polarization-dependent differential cross sections(PDDCSs) and the angular distributions of the product angular momentum with the reactant at different values of initial v or j,the results show that the product scattering and product polarization have strong links with initial vibrational-rotational numbers of v and j.The significant manifestation of the normal DCSs is that the forward scattering gradually becomes predominant with the initial vibrational excitation increasing,and the scattering angle of the HF product taking place on the 3A' potential energy surface is found to be more sensitive to the initial value of v.The product orientation and alignment are strongly dependent on the initial rovibrational excitation effect.With enhancement in the initial rovibrational excitation effect,there is an overall decrease in the product orientation as well as in the product alignment either perpendicular to the reagent relative velocity vector k or along the direction of the y axis,for which the initial rotational excitation effect is much more noticeable than the vibrational excitation effect.Moreover,the initial rovibrational excitation effect on the product polarization is more pronounced for the 3A' potential energy surface than for the 1A' potential energy surface.
The interference between two dissociating wave packets of the I2 molecule driven by femtosecond laser pulses is theoretically studied by using the time-dependent quantum wave packet method.Both the internuclear distanceand velocity-dependent density functions are calculated and discussed.It is demonstrated that the interference pattern is determined by the phase difference and the delay time between two pump pulses.With two identical pulses with a delay time of 305 fs and a FWHM of 20 fs,more interference fringes can be observed,while with two pump pulses with a delay time of 80 fs and a FWHM of 20 fs,only a few interference fringes can be observed.
对于O+NH反应,在~3A″和~1A″势能面(Guadagnini R,Schatz G C,Walch S P.Global potential energysurface for the lowest^1 A′,~3A″,and^1A″states of HNO[J].J.Chem.Phys.,1995,10:774)上,我们运用coupled state or centrifugal sudden(CS)近似和close coupling or Coriolis coupled(CC)方法进行了量子动力学计算.通过比较两种方法得到的总的反应几率,我们发现对于两个势能面上的标题反应,CS近似是失效的.我们还讨论了用CS和CC方法得到的速率常数,并进行了结果比较.
