ULTRAFAST DYNAMICS OF SOLVATION AND ISOTOPE EFFECTS IN DISSOCIATIVE PROCESSES
Open Access
- Author:
- Hydutsky, Darren Paul
- Graduate Program:
- Chemistry
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- March 02, 2007
- Committee Members:
- Albert Welford Castleman Jr., Committee Chair/Co-Chair
James Bernhard Anderson, Committee Member
Karl Todd Mueller, Committee Member
Dennis Lamb, Committee Member - Keywords:
- pump-probe
hydrogen iodide
sulfur dioxide
biradical
cluster solvation
photochmical dissociation
isotope effects - Abstract:
- ABSTRACT The work presented here is part of an ongoing effort in the Castleman group to use clusters as a highly controllable models of phenomena in condensed phase materials. Specifically, how the properties of materials change during the progression from single molecules and atoms to bulk materials. Our focus in this work is the dynamics of atmospherically relevant species such as hydrogen iodide (HI) and sulfur dioxide (SO2.) Specific details are presented in the Chapters 3 and 4 for the HI systems along with Chapters 5 and 6 for SO2. The work on HI pertains to fundamental questions on solvation, such as how many water molecules are required to form ion-pairs in the ground-state and the dynamic behavior of electronically excited species of HI(H2O)n. Additionally, HI(H2O)n clusters serve as good models for heterogeneous processes in the atmosphere. The low coordination and high surface area of a cluster is similar to air/water and air/solid interfaces that are prevalent in aerosols. The HI(H2O)n studies presented in this work discuss evidence for a theoretically predicted excited-state species, the biradical. The work on SO2 pertains to the mechanism and isotope effects in the photochemical dissociation of SO2 at 200 to 197 nm. The motivation stems from questions regarding when the Earth’s atmosphere became oxygen rich. As discussed later, isotopic anomalies in sulfur isotopes found in the Earth’s rock record have been proposed as evidence of a photochemical pathway in the early atmosphere that was shut off when oxygen reached high enough levels to form an ozone layer. The work on SO2 photochemical dissociation attempts to uncover isotope effects that would validate the hypothesis of a photochemical mechanism being responsible for the isotope signature found in Earth’s rock record.