Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Resonances in electron impact on atoms and molecules
Abstract
In this dissertation, resonances in electron impact on several atoms and molecules have been investigated. For the atoms, calculations are given of core-excited Feshbach and shape resonances of Mg and Zn and single particle shape resonances of group IIA atoms. Be, Mg, Ca, Sr and group IIB atoms, Zn and Cd. For the molecules, calculations are given of the shape resonances of ethylene, cyclopropene and cyclobutene. Two different methods have been used for these calculations, depending on the type of resonance being treated. Some practical aspects of the R-matrix method are also discussed because of its advantages and the increasing attention it is receiving in theoretical treatment of scattering problems. The core-excited resonances of Mg and Zn were calculated employing traditional quantum chemistry methods. Both selective CI and pair correlated CI methods were used in Mg core-excited resonances calculation. The resonance widths were calculated using an approximate version of Fano's treatment. The results made it possible to assign the resonances. In case of Zn, only the lowest few resonances are calculated and these use the selective CI method. The similarities between the Mg and Zn results are discussed. Single particle shape resonances of group II atoms were calculated using a modified version of Fano's treatment. The results were in very good agreement with the available experimental results. The negative ions of Ca and Sr are predicted to be stable. Shape resonances of the organic molecules, ethylene, cyclopropene and cyclobutene, were also calculated using the same Fano's treatment. The results also agree well with the experimental ones. The R-matrix method was used to compute the elastic S-wave electron-hydrogen scattering phase shift, and was introduced as an alternative method. It has been shown that some modifications, such as using propagation methods and introducing non-orthogonal radial functions, make the R-matix method useful even without Buttle's correction, a procedure that can be very complicated in many cases. The details of Fano's method are also discussed, particularly with respect to its application to the resonance calculations in atoms and molecules.
Subject Area
Chemistry
Recommended Citation
Chen, Donghai, "Resonances in electron impact on atoms and molecules" (1988). ETD collection for University of Nebraska-Lincoln. AAI8824917.
https://digitalcommons.unl.edu/dissertations/AAI8824917