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Liaros N. Far-field lithography through saturated resonance energy transfer. OPTICS LETTERS 2022; 47:3327-3330. [PMID: 35776617 DOI: 10.1364/ol.461568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
A method based on resonance energy transfer in a donor-acceptor pair is proposed for writing three-dimensional features in the far field. The saturation of the energy transfer between the donor-acceptor pair induces a nonlinear intensity response in the radical population. This optical nonlinearity can enable three-dimensional nanofabrication without requiring the use of the ultrafast excitation that is compulsory for non-resonant multiphoton excitation. Addition of a second, spatially shaped beam can enable nanopatterning far below the diffraction limit.
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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] [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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Cohen SR, Fourkas JT. Extracting Information on Linear and Nonlinear Absorption from Two-Beam Action Spectroscopy Data. J Phys Chem A 2019; 123:7314-7322. [PMID: 31352785 DOI: 10.1021/acs.jpca.9b06068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two-beam action (2-BA) spectroscopies are a recently developed class of techniques for determining the order(s) of absorption (one-photon, two-photon, etc.) that contribute to an observable signal. When only a single order of absorption is present, 2-BA spectroscopies allow for the determination of that order from data obtained at a single value of the observable. It has been shown previously that when two orders of absorption are present, they can be determined unambiguously from measurements made at several values of the observable. However, this latter approach cannot be used for single-valued observables, such as a polymerization threshold. Here we develop a theoretical comparison between conventional methods that determine the order(s) of absorption using logarithmic plots and 2-BA-based techniques. We also explore how 2-BA plots arising from two orders of absorption deviate from a plot with a single, noninteger exponent. We demonstrate that these deviations can usually be used to identify the two orders of absorption and their relative contributions to the signal on the basis of measurements made at a single value of the observable.
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