ORCID

0000-0001-5351-9453

Keywords

photoionization, lasing, plasma, diatomic, atmosphere, spectra

Abstract

This thesis is devoted to the development of the model for total molecular photoionization spectra which is general to diatomic molecules and the application of this model to two benchmark systems, CH and N2, for verification. This model combines multi-channel quantum defect theory, first-principles ab initio molecular calculations, and vibrational frame transformation to accurately model molecular photoionization and electron impact including vibrational dynamics. The scattering data and transition dipole moments for the molecular systems were calculated using R-matrix method through the UKRMol+ codes. A vibrational frame transformation is then performed and multi-channel quantum defect theory is used to calculate closed channel resonances. The matrix of closed-channel coefficients is then analyzed to characterize all of the resonant structures present in the spectra. The electron impact (de-)excitation cross sections were also calculated for the first 9 vibrational levels of the X2Σg, A2Πu and B2Σu of N2 +. The photoionization spectra were compared with current experimental data for their associated molecule in order to verify the model. The experimental studies are the ion yield measurement by Gans et al. for CH and the measurement by Randazzo et al. for N2. To verify the electron impact calculations, the results were compared with the recent theoretical study by Abdoulanziz et al. Both calculated photoionization spectra successfully represented and characterized most resonant structures present in the experimental data. An identification of double-cathedral resonance in the N2 photoionization spectrum shows agreement for the first peak but an argument is made for the missing second peak. The comparison between this calculation of the electron impact rate coefficients and the previous group’s model reveals differences in temperature thresholds, but an argument is made for the rates found within this work. Potential future improvements and additions to the investigation are proposed and discussed.

Completion Date

2026

Semester

Spring

Committee Chair

Viatcheslav Kokoouline

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Physics

Format

PDF

Document Type

Dissertation

Identifier

DP0053100

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