Collisional transfer between excited electronic states as a mechanism for sulfur mass-independent fractionation

The Great Oxygenation Event, the introduction of O2 into the Earth's atmosphere approximately 2.5 billion years ago, is a critical milestone in the development of life on Earth. The exact timing of this event is thought to be correlated with the disappearance of Archean sulfur isotopic anomalies, called Sulfur Mass -Independent Fractionation (S-MIF), in the rock record. This anomalous fractionation pattern can be described, generally, as an enrichment in the three rare isotopes: S-33 (0.75%), S-34 (4.25%) S-36 (0.01%), relative to the most abundant isotopologue S-32 (0.75%), However, the mechanism for the generation of S-MIF in a reducing atmosphere is still unknown. I use the B-X UV transition (~31,000-36,000 cm⁻¹) in S₂ as a proxy for study of excited state collisional transfer as a possible mechanism for S-MIF. The short-lifetime B state (natural lifetime: 32 ns) state-mixes extensively with a longer-lifetime B" state (4200 ns).

Name thesis:degree_name

Doctoral

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Chemistry

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2020

Author dc:creator

• Hull, Alexander W.(Alexander William)

Advisor dc:contributor.advisor

• Robert W. Field.

• Chemistry.

Statement dc:rights

• MIT theses may be protected by copyright. Please reuse MIT thesis content according to the MIT Libraries Permissions Policy, which is available through the URL provided.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1721.1/130591

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/130591