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Bhattacharya A, Singh PJ, Das S. UV-VUV absorption spectra of azido-based energetic plasticizer bis(1,3-diazido prop-2-yl)malonate in gas phase. J Chem Phys 2024; 160:014303. [PMID: 38174794 DOI: 10.1063/5.0187538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 12/11/2023] [Indexed: 01/05/2024] Open
Abstract
Ultraviolet and vacuum ultraviolet photo-absorption spectra of azido (-N3)-based energetic plasticizer, bis(1,3-diazido-prop-2-yl)-malonate (abbreviated as BDAzPM), in the gas phase is recorded at room temperature and in the photon energy range of 5.5-9.9 eV using a synchrotron radiation source. Complementary computational results obtained using the time-dependent density functional theory document the vertical transition energies and oscillator strengths. Comparison of the simulated spectra with the experimental absorption spectrum of BDAzPM reveals that the early part of the absorption spectrum of BDAzPM is of pure valence excitation character, whereas the later intense part of the absorption spectrum is dominated by mixed Rydberg and valence electronic excitations.
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Affiliation(s)
- Atanu Bhattacharya
- Department of Chemistry, School of Science, Gandhi Institute of Technology and Management, GITAM, Deemed to be University, Visakhapatnam, India
| | - Param Jeet Singh
- Atomic and Molecular Physics Division, Bhabha Atomic Research Center, Mumbai, India and Homi Bhabha National Institute, Mumbai, India
| | - Suman Das
- Department of Chemistry, School of Science, Gandhi Institute of Technology and Management, GITAM, Deemed to be University, Visakhapatnam, India
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Poirier CA, Guidry LM, Ratliff JM, Esposito VJ, Marchetti B, Karsili TNV. Modeling the Ground- and Excited-State Unimolecular Decay of the Simplest Fluorinated Criegee Intermediate, HFCOO, Formed from the Ozonolysis of Hydrofluoroolefin Refrigerants. J Phys Chem A 2023; 127:6377-6384. [PMID: 37523496 DOI: 10.1021/acs.jpca.3c01530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Hydrofluoroolefins (HFO) are fourth-generation refrigerants designed to function as efficient refrigerants with no ozone depletion potential and zero global warming potential. Despite extensive studies on their chemical and physical properties, the ground- and excited-state chemistry of their atmospheric oxidation products is less well understood. This study focuses on the ground- and excited-state chemistry of the simplest fluorinated Criegee intermediate (CI), fluoroformaldehyde oxide (HFCOO), which is the simplest fluorinated CI formed from the ozonolysis of HFOs. HFCOO contains syn- and anti-conformers, which have Boltzmann populations of, respectively, 87 and 13% at 298 K. For both conformers, the calculated ground-state reaction energy profiles associated with cyclization to form fluorodioxirane is lower than the equivalent unimolecular decay path in the simplest CI, H2COO, with anti-HFCOO returning a barrier height more than half of that of H2COO. The excited-state dynamics reveal that photoexcitation to the bright S2 state of syn-HFCOO and anti-HFCOO is expected to undergo a prompt O-O fission─with the former conformer expected to dissociate with an almost unity quantum yield and to form both O (1D) + HFCO (S0) and O (3P) + HFCO (T1) products. In contrast, photoexcitation of anti-HFCOO is expected to undergo an O-O bond fission with a non-unity quantum yield. The fraction of photoexcited anti-HFCOO that dissociates is predicted to exclusively form O (1D) + HFCO (S0) products, which is in sharp contrast to H2COO. The wider implications of our results are discussed from both physical and atmospheric chemistry perspectives.
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Affiliation(s)
- Courtney A Poirier
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
- Regional Application Center, NASA/University of Louisiana at Lafayette, Lafayette, Louisiana 70506, United States
| | - Lily M Guidry
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Jordyn M Ratliff
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Vincent J Esposito
- NASA Postdoctoral Program Fellow, NASA Ames Research Center, Moffett Field, California 94035-1000, United States
| | - Barbara Marchetti
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
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Dombrowski DR, Schulz T, Kleinschmidt M, Marian CM. R2022: A DFT/MRCI Ansatz with Improved Performance for Double Excitations. J Phys Chem A 2023; 127:2011-2025. [PMID: 36799533 DOI: 10.1021/acs.jpca.2c07951] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
A reformulation of the combined density functional theory and multireference configuration interaction method (DFT/MRCI) is presented. Expressions for ab initio matrix elements are used to derive correction terms for a new effective Hamiltonian. On the example of diatomic carbon, the correction terms are derived, focusing on the doubly excited 1Δg state, which was problematic in previous formulations of the method, as were double excitations in general. The derivation shows that a splitting of the parameters for intra- and interorbital interactions is necessary for a concise description of the underlying physics. Results for 1La and 1Lb states in polyacenes and 1Au and 1Ag states in mini-β-carotenoids suggest that the presented formulation is superior to former effective Hamiltonians. Furthermore, statistical analysis reveals that all the benefits of the previous DFT/MRCI Hamiltonians are retained. Consequently, the here presented formulation should be considered as the new standard for DFT/MRCI calculations.
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Affiliation(s)
- Dennis R Dombrowski
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Timo Schulz
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Martin Kleinschmidt
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Christel M Marian
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
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Simulating Electronic Absorption Spectra of Atmospherically Relevant Molecules: A Systematic Assignment for Enhancing Undergraduate STEM Education. EDUCATION SCIENCES 2022. [DOI: 10.3390/educsci12040252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Computational and atmospheric chemistry are two important branches of contemporary chemistry. With the present topical nature of climate change and global warming, it is more crucial than ever that students are aware of and exposed to atmospheric chemistry, with an emphasis on how modeling may aid in understanding how atmospherically relevant chemical compounds interact with incoming solar radiation. Nonetheless, computational and atmospheric chemistry are under-represented in most undergraduate chemistry curricula. In this manuscript, we describe a simple and efficient method for simulating the electronic absorption spectral profiles of atmospherically relevant molecules that may be utilized in an undergraduate computer laboratory. The laboratory results give students hands-on experience in computational and atmospheric chemistry, as well as electronic absorption spectroscopy.
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McCoy JC, Léger SJ, Frey CF, Vansco MF, Marchetti B, Karsili TNV. Modeling the Conformer-Dependent Electronic Absorption Spectra and Photolysis Rates of Methyl Vinyl Ketone Oxide and Methacrolein Oxide. J Phys Chem A 2022; 126:485-496. [PMID: 35049299 DOI: 10.1021/acs.jpca.1c08381] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Criegee intermediates are important atmospheric oxidants, formed via the reaction of ozone with volatile alkenes emitted into the troposphere. Small Criegee intermediates (e.g., CH2OO and CH3CHOO) are highly reactive, and their removal via unimolecular decay or bimolecular chemistry dominates their atmospheric lifetimes. As the molecular complexity of Criegee intermediates increases, their electronic absorption spectra show a bathochromic shift within the solar spectrum relevant to the troposphere. In these cases, solar photolysis may become a competitive contributor to their atmospheric removal. In this article, we report the conformer-dependent simulated electronic absorption spectra of two four-carbon-centered Criegee intermediates, methyl vinyl ketone oxide (MVK-oxide) and methacrolein oxide (MACR-oxide). Both MVK-oxide and MACR-oxide contain four low-energy conformers, which are convoluted in the experimentally measured spectra. Here, we deconvolute each conformer and estimate contributions from each of the four conformers to the experimentally measured spectra. We also estimate the photolysis rates and predict that solar photolysis should be a more competitive removal process for MVK-oxide and MACR-oxide (cf. CH2OO and CH3CHOO).
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Affiliation(s)
- Julia C McCoy
- Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States
| | - Spencer J Léger
- Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States
| | - Conrad F Frey
- Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States
| | - Michael F Vansco
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Barbara Marchetti
- Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States
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McCoy JC, Marchetti B, Thodika M, Karsili TNV. A Simple and Efficient Method for Simulating the Electronic Absorption Spectra of Criegee Intermediates: Benchmarking on CH 2OO and CH 3CHOO. J Phys Chem A 2021; 125:4089-4097. [PMID: 33970629 DOI: 10.1021/acs.jpca.1c01074] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Criegee intermediates (CIs) play a vital role in the atmosphere-known most prominently for enhancing the oxidizing capacity of the troposphere. Knowledge of their electronic absorption spectra is of vital importance for two reasons: (1) to aid experimentalists in detecting CIs and (2) in deciding if their removal is affected by solar photolysis. In this article we report a simple and efficient method based on the nuclear ensemble method that may be effectively used to compute the electronic absorption spectra of Criegee intermediates without the need for extensive computation of preparing the initial configurations of the starting geometry. We use this method to benchmark several excited-state electronic structure methods and their efficacy in reproducing the electronic absorption spectra of two well-known cases of CI: CH2OO and CH3CHOO. The success and computational feasibility of the methodology are crucial for its applicability to CIs of increasing molecular complexity, which have no known experimentally measured electronic absorption spectra, allowing a guide for experimentalists. Application of the methodology to more complex CIs (e.g., those with extended conjugation or those derived from endocyclic alkenes) will also reveal if solar photolysis becomes a competitive removal process when compared to unimolecular decay or bimolecular chemistry.
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Affiliation(s)
- Julia C McCoy
- University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
| | - Barbara Marchetti
- University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
| | - Mushir Thodika
- Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Tolga N V Karsili
- University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
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