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Liaros N, Gutierrez Razo SA, Thum MD, Ogden HM, Zeppuhar AN, Wolf S, Baldacchini T, Kelley MJ, Petersen JS, Falvey DE, Mullin AS, Fourkas JT. Elucidating complex triplet-state dynamics in the model system isopropylthioxanthone. iScience 2022; 25:103600. [PMID: 35005547 PMCID: PMC8717599 DOI: 10.1016/j.isci.2021.103600] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/10/2021] [Accepted: 12/03/2021] [Indexed: 11/19/2022] Open
Abstract
We introduce techniques for probing the dynamics of triplet states. We employ these tools, along with conventional techniques, to develop a detailed understanding of a complex chemical system: a negative-tone, radical photoresist for multiphoton absorption polymerization in which isopropylthioxanthone (ITX) is the photoinitiator. This work reveals that the same color of light used for the 2-photon excitation of ITX, leading to population of the triplet manifold through intersystem crossing, also depletes this triplet population via linear absorption followed by reverse intersystem crossing (RISC). Using spectroscopic tools and kinetic modeling, we identify the reactive triplet state and a non-reactive reservoir triplet state. We present compelling evidence that the deactivation channel involves RISC from an excited triplet state to a highly vibrationally excited level of the electronic ground state. The work described here offers the enticing possibility of understanding, and ultimately controlling, the photochemistry and photophysics of a broad range of triplet processes.
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Affiliation(s)
- Nikolaos Liaros
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA
| | | | - Matthew D. Thum
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Hannah M. Ogden
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Andrea N. Zeppuhar
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Steven Wolf
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA
| | | | | | - John S. Petersen
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA
- imec, Kapeldreef 75, 3001 Leuven, Belgium
| | - Daniel E. Falvey
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Amy S. Mullin
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - John T. Fourkas
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA
- Institute for Physical Science & Technology, University of Maryland, College Park, MD 20742, USA
- Maryland Quantum Materials Center, University of Maryland, College Park, MD 20742, USA
- Maryland NanoCenter, University of Maryland, College Park, MD 20742, USA
- Corresponding author
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