A Study of Ultrafast, Intense-field Photodynamics in Carbon Dioxide, Carbon Disulfide, and Select Substituted Benzenes

Authors

Joshua Edwin Beck, University of Nebraska-LincolnFollow

First Advisor

Cornelis Uiterwaal

Degree Name

Doctor of Philosophy (Ph.D.)

Committee Members

Brad Shadwick, Herman Batelaan, Hui Li, Martin Centurion

Department

Physics and Astronomy

Date of this Version

5-2025

Document Type

Dissertation

Citation

A dissertation presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Doctor of Philosophy

Major: Physics and Astronomy

Under the supervision of Professor Cornelis Uiterwaal

Lincoln, Nebraska, May 2025

Comments

Copyright 2025, Joshua Edwin Beck. Used by permission

Abstract

The study of the photodynamics of molecules in ultrashort pulses of intense radiation continues to be of interest. Electric field strengths in such pulses can approach or exceed the typical electric field strengths binding the electrons to the nuclear framework (ke/a²₀ ≈ 5 × 10⁹ V/cm). The resulting excitation, ionization, and dissociation of molecular targets is of interest in many areas including attosecond science, femtochemistry, atmospheric science, high harmonic generation, and many other fields.

This dissertation investigates the photoionization and photofragmentation behavior of carbon dioxide, carbon disulfide, and the substituted benzenes nitrobenzene, aniline, as well as toluene, phenol, and anisole in the gas phase under single-molecule conditions. Using 800 nm, 50-fs laser pulses at intensities ranging from 8 × 10¹² W/cm² to 3 × 10¹⁴ W/cm², time-of-flight mass spectrometry data was collected for each target in the absence of the focal volume effect. For each systematic series, the effect of the different structural parameters are examined. We find many similarities between CO₂ and CS₂, but find differences beyond single ionization. Comparative analysis of aniline and nitrobenzene highlights how electron-donating versus electron-withdrawing substituents influence stability and fragmentation. In toluene, phenol, and anisole ionization dominates over fragmentation, but differences in yield slopes and REMPI signatures underscore the role of molecular substituents and their impact on intermediate state accessibility.

Advisor: Cornelis Uiterwaal

Recommended Citation

Beck, Joshua Edwin, "A Study of Ultrafast, Intense-field Photodynamics in Carbon Dioxide, Carbon Disulfide, and Select Substituted Benzenes" (2025). Dissertations and Doctoral Documents from University of Nebraska-Lincoln, 2023–. 313.
https://digitalcommons.unl.edu/dissunl/313