Effects of the vibrational and rotational excitation of reagent on the stereodynamics of the reaction S (3P) ＋ H2→ SH ＋ H

Quasiclassical trajectory （QCT） calculations are first carried out to study the stereodynamics of the S （3p） ＋ H2 → SH ＋ H reaction based on the ab initio 13Atr potential energy surface （PES） （Lii etal. 2012 J. Chem. Phys. 136 094308）. The QCT-calculated reaction probabilities and cross sections for the S ＋ H2 （v = 0, j = 0） reaction are in good agreement with the previous quantum mechanics （QM） results. The vector properties including the alignment, orientation, and polarization- dependent differential cross sections （PDDCSs） of the product SH are presented at a collision energy of 1.8 eV. The effects of the vibrational and rotational excitations of reagent on the stereodynamics are also investigated and discussed in the present work. The calculated QCT results indicate that the vibrational and rotational excitations of reagent play an important role in determining the stereodynamic properties of the title reaction.

The effect of the rotational excitation of NO on the stereodynamics for the reaction C(~3P)+NO(X^2Π)→CN(X^2Σ^+)+O(~3P)

The stereodynamic properties of the reaction C （^3P） ＋ NO （X2^П） →CN （X^2∑^＋） ＋ O （^3P） in different rotational states of reactant NO are studied theoretically by using the quasiclassical trajectory method on ^2A″ and ^2A′ potential energy surfaces （PESs） at a collision energy of 0.06 eV. The vector properties in different rotational states on the two surfaces are discussed in detail. The results indicate that the rotational excitation of NO has considerable influence on the stereodynamic property of the reaction occurring on the two surfaces. At the same time, the calculated polarization-dependent differential cross sections （PDDCSs） in different initial rotational states manifest that products are strongly polarized at three scattering angles.

Effects of Vibrational and Rotational Excitations on Dissociative Chemisorption Dynamics of N_(2) on Fe(111)

The dissociative chemisorption of N_(2) is the rate-limiting step for ammonia synthesis in industry.Here,we investigated the role of initially vibrational excitation and ro-tational excitation of N_(2) for its reactivity on the Fe(111)surface,based on a recently developed six-dimensional potential energy surface.Six-dimensional quantum dynamics study was carried out to investi-gate the effect of vibrational excitation for incidence energy below 1.6 eV,due to sig-nificant quantum effects for this reaction.The effects of vibrational and rotational excitations at high incidence energies were revealed by quasiclassical trajectory calculations.We found that raising the translational energy can enhance the dissociation probability to some extent,however,the vibrational excitation or rotational excitation can promote disso-ciation more efficiently than the same amount of translational energy.This study provides valuable insight into the mode-specific dynamics of this heavy diatom-surface reaction.

Effects of Single Quantum Rotational Excitation on Reaction of F+D_(2) at Collision Energies between 44 and 164 cm^(-1)

There is no general picture to describe the influences of reagent rotational excitation on the reaction,which proceeds via the tunnelling mechanism at collision energies far below the reaction barrier.Here we report a crossed beam study on the prototypical reaction of F+D_(2)(v=0,j=0,1)→DF(v′)+D at collision energies between 44 and 164 cm^(-1)with the scheme of multichannel D-atom Rydberg tagging time-of-flight detection.Vibrational state resolved differential cross sections are obtained at v′=2,3,4 levels.The effects of reagent rotational excitation were investigated at an equivalent amount of total energy by precise tuning of translational energies.Compared with translation,the rotation of D_(2) is found to be more efficient to promote the title reaction.Profound differences introduced by rotation of D_(2) are also observed on the angular distribution and quantum state distribution of DF products.We hope the present work could provide an example for understanding the effects of reagent rotational excitation on the chemical reaction at energies that are much lower than the reaction barrier.

On rotational normal modes of the Earth：Resonance,excitation,convolution, deconvolution and all that

Earth＇s Coriolis force profoundly alters the eigen frequencies, eigen functions, and excitation of rotational normal modes. Some rotational modes of the solid mantle-fluid outer core-solid inner core Earth system are confirmed observationally and some remain elusive. Here we bring together from literature assertions about an excited resonance system in terms of the Green＇s function and temporal convolution. We raise caveats against taking the face values of the oscillational motion which have been ＂masqueraded＂ by the convolution, necessitating deconvolution for retrieving the excitation function which reflects the true variability. Lastly we exemplify successful applications of the deconvolution in estimating resonance complex frequencies.

Effect of ro-vibrational excitation of NeH^+ on the stereodynamics for the reactions H+NeH^+(v=1-3,j=1,3,5) →H_2^++Ne

The stereodynamics of the abstraction reaction H^＋ NeH^＋（v = 1-3,j = 1,3,5） → H2^＋ ＋ Ne is studied theoretically with a quasi-classical trajectory method on a new ab initio potential energy surface [ S J,Zhang P Y,Han K L and He G Z 2012 J.Chem.Phys.132 014303].The effects of vibrational and rotational excitation of reagent molecules on the polarization of the product are investigated.The reaction cross sections,the distributions of P（θr）,P（φr）,and polarizationdependent differential cross sections（PDDCSs） are calculated.The obtained cross sections indicate that the title reaction is a typical barrierless atom（ion）-ion（molecule） reaction.The initial vibrational excitation and rotational excitation of reagent molecules have distinctly different influences on stereodynamics of the title reaction,and the possible reasons for the differences are presented.

The stereodynamic properties of the F+HO(v,j) → HF+O reaction on^1 A' and ~3A' potential energy surfaces by quasi-classical trajectory calculations:Initial excitation effect(v=1-3, j=0 and v= 0, j=1-3)

The stereodynamic properties of the F ＋ HO （v, j） reaction are explored by quasi-classical trajectory （QCT） calculations performed on the 1At and 3At 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 vibrationalrotational 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 3At 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 3At potential energy surface than for the 1At potential energy surface.

Understanding Rotational Mode Specificity in the O（3P）+CHD3→OH+CD3 Reaction by Simple Reactant Alignment Pictures

The mode specificity plays an important role in understanding the fundamental reaction dynamics. This work reports a theoretical study of the rotational mode specificity of the reactant CHD3(JK) in the prototypical hydrocarbon oxidation reaction O(3P)+CHD3→OH+CD3. The time-dependent quantum wave packet method combined with a seven-dimensional reduced model is employed to calculate the reaction probability on an accurate potential energy surface. The obtained reaction probability depends on the values of both K and Ktot with PKtot=K=0>PKtot=K=J>PKtot=J,K=0=PKtot=0,K=J. This observation can be well rationalized by the reactant alignment pictures. Rotational excitations of CHD3 up to the angular momentum quantum number J=4 have a very weak enhancement effect on the reaction except for the state (J=4, K=0). In addition, the rotationally excited states of CHD3 with K=0 promote the reaction more than those with K=J. The quantum dynamics calculations indicate that the K=0 enhancements are mainly caused by the contributions from the components with K=Ktot=0. The components correspond to the tumbling rotation of CHD3, which enlarges the range of the reactive initial attack angles.

Dynamics of the reaction of O with H_2 and its isotopic variants in different rotational excited states

Scalar properties and vector correlations of the reactions of O＋H2 →OH＋H, O＋HD→OH＋D, O＋DH→OD＋H, and O＋D2 -＋OD＋D at collision energies of 25 and 34.6 kcal/mole have been studied via the quasi-classical-trajectory （QCT） method based on a BMS1 potential energy surface （PES）. The generalized polarization-dependent differential cross section and the distributions of the dihedral angle at the collision energy of 34.6 kacl/mole are presented. The calculated results indicate that both the reagent rotational angular momentum and the mass factor have a significant influence on the scalar properties and vector correlations of the title reactions.

Energy and rotation-dependent stereodynamics of H(~2S) + NH(a^1?) → H_2(X^1Σ_g^+) + N(~2D) reaction

Quasi-classical trajectory calculations are performed to study the stereodynamics of the H（~2S） ＋ NH（a^1？） →H_2（X^1Σ_g~＋） ＋ N（~2D） reaction based on the first excited state NH_2（1~2A＇） potential energy surface reported by Li et al.[Li Y Q and Varandas A J C 2010 J. Phys. Chem. A 114 9644] for the first time. We observe the changes of differential cross-sections at different collision energies and different initial reagent rotational excitations. The influence of collision energy on the k-k＇ distribution can be attributed to a purely impulsive effect. Initial reagent rotational excitation transforms the reaction mechanism from insertion to abstraction. The effect of initial reagent rotational excitations on k-k＇ distribution can be explained by the rotational excitation enlarging the rotational rate of reagent NH in the entrance channel to reduce the probability of collision between incidence H atom and H atom of target molecular. We also investigate the changes of vector correlations and find that the rotational angular momentum vector j＇ of the product H_2 is not only aligned, but also oriented along the y axis. The alignment parameter, the disposal of total angular momentum and the reaction mechanism are all analyzed carefully to explain the polarization behavior of the product rotational angular moment.

Quasiclassical trajectory theoretical study on the chemical stereodynamics of the O(~1D)+H_2→OH+H reaction and its isotopic variants (HD, D_2)

The quasiclassical trajectory （QCT） method is used to study stereodynamic information about the reaction O （1D）＋H2 --4OH＋H on the DK （Dobbyn and Knowles） （llA;） ab initio potential energy surface （PES）. A wide scale of collision energy （Ec） from 0.05 eV to 0.5 eV is considered in the dynamic calculations. To reveal the rovibrational excitation effect, calculations at a collision energy of 0.52 eV are carried out for the v = 0 - 5, j = 0 and v = 0, j -- 0 - 15 initial states. The two popularly used polarization-dependent differential cross sections （PDDCSs）, dtY0o/doh （0, 0） and dtra0/dtot（2, 0）, and two angular distributions, P（φr） and P（φr） are calculated to obtain an insight into the alignment and the orientation of the product molecules. From the calculations, we can obtain that the alignment of the OH product is weaker at high collision energy and becomes stronger with the increase of initial vibrational level, and it is almost insensitive to the initially rotational excitation. Influences of the mass values of isotopes （HD, D2） on the stereodynamics are also shown and discussed. Comparisons between available theoretical results and experimental results are made and discussed.

Spin noise spectroscopy of rubidium atomic gas under resonant and non-resonant conditions

The spin fluctuation in rubidium atom gas is studied via all-optical spin noise spectroscopy（SNS）.Experimental results show that the integrated SNS signal and its full width at half maximum（FWHM） strongly depend on the frequency detuning of the probe light under resonant and non-resonant conditions.The total integrated SNS signal can be well fitted with a single squared Faraday rotation spectrum and the FWHM dependence may be related to the absorption profile of the sample.

Fano resonance and magneto-optical Kerr rotaion in periodic Co/Ni complex plasmonic nanostructure

we report a pure rerromagneuc metallic magnetopiasmonic structure consisting or two-dimensional oraerea Ni nanodisks array on Co film.With a sufficient height of the nanodisks,a steep and asymmetric Fano resonance can be excited in this structure.We attribute the fascinating spectral lineshape to the strong coupling between the excitation of surface plasmon polaritons at the interface and the localized surface plasmon resonance of nanodisks.The conclusion is fully confirmed by spectrum measurements in nanostructures with different heights.Furthermore,the enhancement and sign of the magneto-optical Kerr rotation in this structure are significantly modified by the Fano resonance.

Production of cold CN molecules by photodissociating ICN precursors in brute-force field

We theoretically investigate the production of cold CN molecules by photodissociating ICN precursors in a brute-force field. The energy shifts and adiabatic orientation of the rotational ICN precursors are first investigated as a function of the external field strength. The dynamical photofragmentation of ICN precursors is numerically simulated for cases with and without orienting field. The CN products are compared in terms of their velocity distributions. A small portion of the CN fragments are recoiled to near zero speed in the lab frame by appropriately selecting the photo energy for dissociation. With a precursor ICN molecular beam of - 1.5 K in rotational temperature, the production of low speed CN fragments can be improved by more than 5 times when an orienting electrical field of 100 k V/cm is present. The corresponding production rate for decelerated fragments with speeds ≤ 50 m/s is simulated to be about ～2.1×10^-4 and CN number densities of 10^8 –10^10 cm^-3 can be reached with precursor ICN densities of ～10^12 –10^14 cm^-3 from supersonic expansion.

Shape Decoupling Effects and Rotation of Deformed Halo Nuclei

With the development of radioactive-ion-beam facilities,many exotic phenomena have been discovered or predicted in the nuclei far from the stability line,including cluster structure,shell structure,deformed halo,and shape decoupling effects.The study of exotic nuclear phenomena is at the frontier of nuclear physics nowadays.The covariant density functional theory(CDFT)is one of the most successful microscopic models in describing the structure of nuclei in almost the whole nuclear chart.Within the framework of CDFT,toward a proper treatment of deformation and weak binding,the deformed relativistic Hartree-Bogoliubov theory in continuum(DRHBc)has been developed.In this contribution,we review the applications and extensions of the DRHBc theory to the study of exotic nuclei.The DRHBc theory has been used to investigate the deformed halos in B,C,Ne,Na,and Mg isotopes and the theoretical descriptions are reasonably consistent with available data.A DRHBc Mass Table Collaboration has been founded,aiming at a high precision nuclear mass table with deformation and continuum effects included,which is underway.By implementing the angular momentum projection based on the DRHBc theory,the rotational excitations of deformed halos have been investigated and it is shown that the deformed halos and shape decoupling effects also exist in the low-lying rotational excitation states of deformed halo nuclei.

Rotating deformed halo nuclei and shape decoupling effects

To explore the rotational excitation of deformed halo nuclei,the angular momentum projection(AMP)has been implemented in the deformed relativistic Hartree-Bogoliubov theory in continuum(DRHBc),in which both the mean field and collective wave functions are expanded in terms of Dirac WoodsSaxon basis.The DRHBc+AMP approach self-consistently describes the coupling between single particle bound states and the continuum not only in the ground state but also in rotational states.The rotational modes of deformed halos in ^(42,44)Mg are investigated by studying properties of rotational states such as the excitation energy,configuration,and density distribution.Our study demonstrates that the deformed halo structure persists from the ground state in the intrinsic frame to collective states.Especially,the typical behavior of shape decoupling effects in rotating deformed halo nuclei is revealed.