Collisional Breakup Dynamics Of Complex Atoms And Molecules

In the past decades,the collisional breakup dynamic of atoms and molecules have been studied widely in theory and experiment.However,the successful studies are limited to the simple atom(H,He and alkaline metal atoms)and diatomic molecules(H23 O2,N2 and CO).For more complex atoms and molecules,it is difficult to understand the complecated multi-body momentum correlation observed in experiment since the Schrodinger equation of three-body/more-body system can not solve exactly.Based on the previous works of our group,we independently develop new theoretical models and corresponding programs to investigate the collisional breakup reactions of complex atoms and molecules.Firstly,we proposed a new theory to investigate the three-body correlations among two outgoing electrons and one residual ion after the electron-impact ionization of complex atoms.We extended the first-order distorted wave Born approximation(DWBA)theory to the high-order one,where the interaction between two outgoing electrons(post-collision interaction)and the polarization interactions between electrons and residual ion are considered accurately.Using the DWBA method developed,we calculated the absolute triple differential cross sections(DCS)for single ionization of Ne(2p)at an impact energy of 599.6 eV and Ar(3p)at 195 eV.Compared with the results of previous first-order DWBA and other sophisticated non-perturbation methods,much better agreements of DCSs are found in comparison with experiments both in the shape and magnitude.Our work indicates that it is feasible to use the high-order perturbative method to obtain high-precision absolute cross sections for the electron-impact ionization reaction of complex atoms.In addition,we also investigate the three-body momentum correlations of non-sequential three-body breakup processes of Ar and Xe in laser field.Our theoretical results perfectively predict the maximum and minimum of the differential cross section observed in the experiment,and verify the electronic correlation feature of the non-sequential double ionization of atoms in laser field.Due to the high precision and high efficiency of the developed DWBA method,it can be used to perform large scale calculations of(e,2e)cross section and provide atomic data for related studies of national large scientific projectSecondly,we performed systematic Coulomb Explosion simulations of molecular ions and examined the reliability of Coulomb Explosion Imaging(CEI)technique of molecular dimers.We simulated the three-body breakup processes of H2Ar3+,N2Ar3+and ArCO3+by the semi-classical trajectory method and Landau-Zener surface hopping method,and the final momentums of three charged fragments are obtained,which show that the information of three-body momentum correlation for the breakups of H2Ar3+and N2Ar3+are directly related to the initial geometries of neutral molecular dimers.However,for the rapid three-body breakups of ArCO3+,we found that,due to the interaction between the metastable CO2+and Ar+ions,ArCO3+changes from its initial T-shape into the more stable Linear-shape within 100 fs,and such a rotation of CO2+is hundreds of times faster than the field free case.As a result,the geometry reconstructed through CEI technique based on the charged fragment momenta would differs from its neutral counterpartFinally,we investigated the energy and ion transfer processes in moleculr/cluster ion A2+·B.We simulated the radiative charge transfer process of He·He2+and obtained the kinetic energy release(KER),which agrees well with the corresponding experimental results.Then we study the relaxation processes of N2·Ar2+,which indicated that the N2·Ar2+ions can relax excessive energy by direct single electron transfer process and generate the high-excited N2+ions.For such system,the radiative charge transfer process would be suppressed.Moreover,we predicted theoretically and observed experimentally the heavy ion transfer process in the breakups of doubly charged N2Ar van der Waals cluster,i.e.N22+·Ar?N++NAr+.Such a process is induced by the three-body momentum transfer among two charged fragments and one neutral particle.The theoretical calculations show that the polarization interactions between Ar and N22+lead to an isomerization process from the initial T-shape to Linear-shape(N-N-Ar).The neighboring neutral Ar decreases the barrier height and width of N22+significantly,resulting in the lifetimes of metastable state of N22+(X1?g+,a3?u)much shorter.Consequently,the breakup of N-N bond,tunneling of the N+ion from N22+,and the formation of N-Ar+take place nearly simultaneously.Then the Coulomb explosion starts between N+and NAr+ion pairs.Such a ion transfer mechanism might be general for other heavy ions,such as O+,C+,and even the ionic functional group-NH2,-OH,and would be of potential importance in understanding the dynamics of the bio-systemsThe organization of the thesis is as follows.In the first chapter,the background and significance of the present work are introduced.The results of electron-impact ionization of complex atoms and the electron-electron-ion momentum correlation effects obtained are presented in second chapter.The results of coulomb explosion simulation and the correlation effects found between the momentums of final three-charged fragments are presented in third chapter,in which the examination for the reliability of Coulomb Explosion Imaging technique are checked.The studies of collisional breakup dynamic of molecular dimers A2+·B are presented in chapter 4.In the last chapter,the conclusions and outlook of our study are given.