Off-campus WSU users: To download campus access dissertations, please use the following link to log into our proxy server with your WSU access ID and password, then click the "Off-campus Download" button below.
Non-WSU users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Access Type
WSU Access
Date of Award
January 2024
Degree Type
Dissertation
Degree Name
Ph.D.
Department
Chemistry
First Advisor
Wen Li
Abstract
The demand for innovative technologies has grown exponentially year by year. In recent years, advances in the field of laser spectroscopy have revealed nuclear and electronic dynamics that have not been available previously. 3D momentum imaging has been a powerful tool used in ultrafast science studying photoionization/dissociation processes in gas phase. We have extended the use of 3D momentum imaging in analyzing solids/surfaces. We achieved a ~ 64 ps timing resolution in measuring time of flight (TOF) with the new 3D momentum imaging apparatus, which is well suited to perform electron and ion imaging. We utilized the newly implemented 3D momentum imaging apparatus to study the mechanism of MALDI primary ionization. Despite being one of the widely used tools in analytical chemistry, its primary ionization mechanism is poorly understood. We experimentally measured the work function and exciton life-time of 2,5-dihydroxybenzoic acid, a commonly employed MALDI matrices. From these results, we determined that multi-photon ionization plays a dominant role in primary ionization in MALDI.Furthermore, even though people speculated that in MALDI, negative ions are formed via electron attachment in the plume, there was no direct experimental evidence. We implemented a high-voltage pulsing scheme to control the electron emission time into the plume. We demonstrated that delaying the electron emission enhances the formation of negative ions and showed the timing characteristic of electrons involved in forming negative ions. Finally, the role of resonance is often overlooked in tunneling ionization, especially in attoclock studies. Here, we theoretically investigated the effect of resonance on the attoclock deflection angle. We observed in argon that a resonance between the Rydberg states can have a significant impact on the deflection angles. This observation suggests that the interpretation of attoclock experiments have to include the effect of resonance.
Recommended Citation
Ranathunga, Yasashri Ranganath, "Imaging And Modeling Multi-Photon Dynamics In Atoms And Surfaces" (2024). Wayne State University Dissertations. 4124.
https://digitalcommons.wayne.edu/oa_dissertations/4124