Browsing by Author "Frontiera, Renee R"

Now showing 1 - 4 of 4
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    Data for Wavelength Dependence of Plasmon-Induced Vibrational Energy Transfer in Fluorophore–Plasmonic Systems
    (2024-08-01) Christenson, Gerrit N; Yu, Ziwei; Frontiera, Renee R; rrf@umn.edu; Frontiera, Renee R; Materials Research Science & Engineering Center
    Understanding, predicting, and controlling plasmon–molecule energy transfer are important for improvements to plasmonic photocatalysis and photothermal therapies. Here, we use continuous wave surface-enhanced anti-Stokes and Stokes Raman spectroscopy to quantify the vibrational kinetic energy, equivalent to a molecular temperature under a Boltzmann approximation, of Raman-active vibrational modes of molecules at plasmonic interfaces. In previous work from our group, we observed an anomalous steady-state reduction in vibrational kinetic energies in benzenethiols absorbed onto the surface of gold nanoparticles. To further explore this effect, here, we quantify the wavelength dependence of vibrational energy in plasmon–fluorophore systems, where molecules can undergo electronic transitions with resonant excitation. We used three excitation wavelengths and three molecules with varying electronic resonance energies. We observe wavelength-dependent vibrational energy distributions, which we attribute to competing effects of on-resonance heating and off-resonance decrease in the population ratio. This work thus quantifies the resonance wavelength dependence of vibrational energy in plasmon molecular systems and helps to suggest future applications of tailored systems with controllable energy transfer pathways.
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    Evidence for superoxide-initiated oxidation of aniline in water by pulsed, atmospheric pressure plasma
    (2024-05-13) Clay, Collin D; Mueller, Chelsea M; Rich, Christopher; Schatz, George C; Bruggeman, Peter; Frontiera, Renee R; rrf@umn.edu; Frontiera, Renee R
    Plasma-driven solution electrochemistry (PDSE) uses plasma-generated reactive species to drive redox reactions in solution. Non-thermal, atmospheric pressure plasmas, when irradiating water, produce many redox species. While PDSE is a promising chemical tool, there is limited insight into the mechanisms of the reactions due to the variety of short-lived reagents produced. In this study, we use aniline as a model system for studying redox mechanisms of PDSE. We show that the plasma irradiation of aqueous aniline solutions drives the formation of polyaniline oligomer, which is suppressed under acidic starting conditions. The addition of (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO), a radical scavenger, decreases the formation of oligomer by 80%, and the addition of superoxide dismutase fully hinders oligomerization. These results lead us to conclude that the oligomerization of aniline by plasma irradiation is initiated by superoxide. This discovery provides novel insights into PDSE mechanisms and illustrates a potential method of harnessing superoxide for chemical reactions.
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    Femtosecond stimulated Raman spectroscopy – guided library mining leads to efficient singlet fission in rubrene derivatives
    (2021-09-28) Bera, Kajari; Douglas, Christopher J; Frontiera, Renee R; rrf@umn.edu; Frontiera, Renee R; Frontiera lab
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    The FSRS data of crystalline halogen-substituted rubrene derivatives under different excitation conditions taken in the Frontiera lab at the University of Minnesota in 2022
    (2024-05-16) Clapham, Margaret L; Das, Aritra; Douglas, Christopher J; Frontiera, Renee R; rrf@umn.edu; Frontiera, Renee R; University of Minnesota Frontiera Lab
    These are the FSRS data files of crystalline halogen-substituted rubrene derivatives under different excitation conditions, taken in the Frontiera lab at the University of Minnesota in 2022. This data is released to support a publication submitted to the Journal of the American Chemical Society entitled "Killer Phonon Caught: Femtosecond Stimulated Raman Spectroscopy Identifies Phonon-Induced Control of Photophysics in Rubrene Derivatives".