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Abeysooriya DNKH, White NJ, Workman KT, Dupuy JA, Gichuhi WK. Cyanocyclopentadiene-Annulated Polycyclic Aromatic Radical Anions: Predicted Negative Ion Photoelectron Spectra and Singlet-Triplet Energies of Cyanoindene and Cyanofluorene Radical Anions. J Phys Chem A 2024. [PMID: 38437617 DOI: 10.1021/acs.jpca.3c08312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
Isomer-specific negative ion photoelectron spectra (NIPES) of cyanoindene (C9H7CN) and cyanofluorene (C14H9N), acquired through the computation of Franck-Condon (FC) factors that utilize harmonic vibrational frequencies and normal mode vectors derived from density functional theory (DFT) at the B3LYP/aug-cc-pVQZ and 6-311++G(2d,2p) basis sets, are reported. The adiabatic electron affinity (EA) values of the ground singlet (S0) and the lowest lying triplet (T1) states are used to predict site-specific S0-T1 energies (ΔEST). The vibrational spectra of the S0 and T1 states are typified by ring distortion and ring C-C stretching vibrational progressions. Among all the S0 isomers in C9H7CN, the 2-cyanoindene (2-C9H7CN) is found to be the most stable at an EA of 0.716 eV, with the least stable isomer being the 1-C9H7CN at an EA of 0.208 eV. In C14H9N, the most stable S0 isomer, 2-cyanofluorene (2-C14H9N), has an EA of 0.781 eV. The least stable S0 isomer in C14H9N is the 9-C14H9N, with an EA of 0.364 eV. The FC calculations are designed to mimic simulations that would be performed to aid in the analysis of experimental spectra obtained in NIPE spectroscopic techniques. The vibrational spectra, adiabatic EAs, and ΔEST values reported in this study are intended to act as a guide for future gas-phase ion spectroscopic experiments and astronomical searches, especially with regard to the hitherto largely unexplored C14H9N isomers.
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Affiliation(s)
- Dushmantha N Koku Hannadige Abeysooriya
- Department of Chemistry, Tennessee Tech University, 1 William L. Jones Dr., Cookeville, Tennessee 38505, United States
- School of Environmental Studies, Tennessee Tech University, 1 William L. Jones Dr., Cookeville, Tennessee 38505, United States
| | - Nolan J White
- Department of Chemistry, Tennessee Tech University, 1 William L. Jones Dr., Cookeville, Tennessee 38505, United States
- Department of Chemical Engineering, Tennessee Tech University, 1 William L. Jones Dr., Cookeville, Tennessee 38505, United States
| | - Kie T Workman
- Department of Chemistry, Tennessee Tech University, 1 William L. Jones Dr., Cookeville, Tennessee 38505, United States
- Department of Chemical Engineering, Tennessee Tech University, 1 William L. Jones Dr., Cookeville, Tennessee 38505, United States
| | - Jonathan A Dupuy
- Department of Chemistry, Tennessee Tech University, 1 William L. Jones Dr., Cookeville, Tennessee 38505, United States
| | - Wilson K Gichuhi
- Department of Chemistry, Tennessee Tech University, 1 William L. Jones Dr., Cookeville, Tennessee 38505, United States
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Pandey RK, Srikanth K, Tripathi SS, Rajagopala Rao T. Resolving the Experimental Photoelectron Spectra of CAl 3Si . J Phys Chem A 2024; 128:355-369. [PMID: 38189257 DOI: 10.1021/acs.jpca.3c06295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
The experimental photoelectron spectra concerning the six electronic states of CAl3Si- are resolved through electronic structure calculations and quantum nuclear dynamics in this study. It incorporates a model diabatic Hamiltonian to evaluate the coupling parameters and fit the potential energy curves (PECs). The analysis of these PECs showed us that there are sufficient nonadiabatic effects in the photoelectron spectra through the presence of various conical intersections. Poisson intensity distributions (PIDs) and the wave packet density plots are utilized for assigning the fundamental and first overtone excitations. The nuclear dynamics study is accomplished by employing time-dependent (TD) and time-independent (TI) quantum chemistry methods. Ultimately, our theoretical results concurred well with the experimental findings exhibiting vibronic coupling amidst the nearly positioned electronic states.
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Affiliation(s)
- Rishabh Kumar Pandey
- Department of Chemistry, Indian Institute of Technology Patna, Bihta 801106, India
| | - Korutla Srikanth
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
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Pandey RK, Srikanth K, Tak A, Kumar A, Rao TR. A theoretical study of vibronic coupling in the photoelectron spectra of Al 6N . Phys Chem Chem Phys 2023; 25:12990-13003. [PMID: 37165932 DOI: 10.1039/d3cp00836c] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
This work emphasizes the appearance of non-adiabatic effects in the photoelectron spectra of Al6N-. It includes ab initio electronic structure calculations obtained on the first seven low-lying electronic states of Al6N- and a nuclear dynamics study utilizing time-dependent and time-independent quantum chemistry approaches. A model vibronic Hamiltonian is constructed in a diabatic electronic representation to estimate the coupling parameters corresponding to the fifteen vibrational modes of Al6N-. Theoretical spectral bands are achieved by employing the vibronic coupling theory followed by reduced dimensional calculations to understand the role of individual vibrational modes in the overall photoelectron spectra. Finally, the theoretically obtained photodetachment spectra show good agreement with the experimental spectra revealing vibronic coupling among the closely spaced spectral bands.
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Affiliation(s)
- Rishabh Kumar Pandey
- Department of Chemistry, Indian Institute of Technology Patna, Bihta, Bihar, 801106, India.
| | - Korutla Srikanth
- Department of Chemistry, Indian Institute of Technology Patna, Bihta, Bihar, 801106, India.
| | - Anuj Tak
- Department of Chemistry, Indian Institute of Technology Patna, Bihta, Bihar, 801106, India.
| | - Abhishek Kumar
- Indian Association for Cultivation of Science, Kolkata, West Bengal, 700032, India
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Srikanth K, Kumar A, Tammineni RR. Unraveling the Photoelectron Spectrum of 1-Phospha-2,3,4-triazolate Anion, HCPN 3-, A Theoretical Approach. J Phys Chem A 2023; 127:78-91. [PMID: 36563286 DOI: 10.1021/acs.jpca.2c06701] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The first five low-lying electronic states of HCPN3 are probed through extensive ab initio electronic structure and quantum dynamics studies to reproduce the 193 nm photoelectron spectrum. Vibronic Hamiltonian is constructed and availed for time-dependent (TD) and time-independent (TI) quantum dynamical studies. The presence of numerous conical intersections (CIs) and crossings among electronic states yielded interesting nonadiabatic effects in the photoelectron bands of the overall spectrum. Moreover, the theoretical bands corresponding to five electronic states have reproduced all three experimental spectral bands. Among these, the first two bands originated due to a combination of four electronic states as predicted by previous studies. The third band corresponds to the fifth electronic state. The results calculated via TD and TI approaches exhibited satisfying agreement with the experimental results.
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Affiliation(s)
- Korutla Srikanth
- Department of Chemistry, Indian Institute of Technology Patna, Patna801106, India
| | - Abhishek Kumar
- Department of Chemistry, Indian Institute of Technology Patna, Patna801106, India
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Yu C, Xiao Z, Dong B, Chu W, Guan J, Wang Z, Zhang Q, Chen Y, Zhao D. Gas-Phase Optical Spectra of the Indenyl Radical and Its Quantitative Detection in a Jet-Stirred Reactor. J Phys Chem A 2022; 126:4630-4635. [PMID: 35793234 DOI: 10.1021/acs.jpca.2c03024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Resonance-stabilized radicals (RSRs), such as the indenyl radical (C9H7), are proposed to be initiator radicals in soot inception and growth in hydrocarbon combustion processes, but spectroscopic data for many RSRs are still lacking. In this work, the gas-phase optical absorption spectra of the B̃2A2-X̃2A2 electronic transition of indenyl were identified in a supersonic indene/argon plasma jet. Spectroscopic parameters, including the transition energy, rotational constants, and upper-state lifetime broadening, were obtained from analysis of the experimental spectra. The results were readily applied to the quantitative detection of indenyl produced from high-temperature reactions in a jet-stirred reactor. This study now makes indenyl optically accessible in further reaction kinetics studies and in situ spectroscopic diagnostics of hydrocarbon combustion processes.
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Affiliation(s)
- Chunting Yu
- Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Zengjun Xiao
- Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Bin Dong
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Wangyou Chu
- Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Jiwen Guan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Zhandong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Qiang Zhang
- Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Yang Chen
- Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Dongfeng Zhao
- Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
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Kumar A, Srikanth K, Sarkar K, Sarkar R, Rao TR. Understanding of the Photodetachment Spectrum of Anionic Mixed Carbon-Boron Cluster C 3B 5- Following Adiabatic and Nonadiabatic Quantum Chemistry Approaches. J Phys Chem A 2022; 126:4563-4576. [PMID: 35796655 DOI: 10.1021/acs.jpca.2c01683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The presence of nonadiabaticity in the photodetachment bands of the anionic mixed carbon-boron cluster C3B5- has been realized through ab initio electronic structure calculations and detailed analyses of quantum dynamics study on top of those electronic structures. In the course of our study, we traverse extensive first principles electronic structure calculations to compute potential energy curves and to trace the energetic locations for the conical intersections in the multidimensional surfaces. All the ab initio calculations are performed on the four low-lying electronic states of the C3B5 cluster, while quantum nuclear dynamics are pursued on those electronic states by applying both time-dependent and time-independent quantum chemistry frameworks. In particular, we rely on the diabatic electronic representation to construct the molecular Hamiltonian. Altogether, the simulated theoretical spectra offer exceptional agreement with the experimental attainments.
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Affiliation(s)
- Abhishek Kumar
- Department of Chemistry, Indian Institute of Technology Patna, Patna 801106, India
| | - Korutla Srikanth
- Department of Chemistry, Indian Institute of Technology Patna, Patna 801106, India
| | - Kanchan Sarkar
- Institut für Theoretische Chemie, Universität Ulm, 89081 Ulm, Germany
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Ross SD, Flores J, Khani S, Hewett DM, Reilly NJ. Optical Identification of the Resonance-Stabilized para-Ethynylbenzyl Radical. J Phys Chem A 2021; 125:9115-9127. [PMID: 34614356 DOI: 10.1021/acs.jpca.1c07039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the spectroscopic observation of the jet-cooled para-ethynylbenzyl (PEB) radical, a resonance-stabilized isomer of C9H7. The radical was produced in a discharge of p-ethynyltoluene diluted in argon and probed by resonant two-color two-photon ionization (R2C2PI) spectroscopy. The origin of the D0(2B1)-D1(2B1) transition of PEB appears at 19,506 cm-1. A resonant two-color ion-yield scan reveals an adiabatic ionization energy (AIE) of 7.177(1) eV, which is almost symmetrically bracketed by CBS-QB3 and B3LYP/6-311G++(d,p) calculations. The electronic spectrum exhibits pervasive Fermi resonances, in that most a1 fundamentals are accompanied by similarly intense overtones or combination bands of non-totally symmetric modes that would carry little intensity in the harmonic approximation. Under the same experimental conditions, the m/z = 115 R2C2PI spectrum of the p-ethynyltoluene discharge also exhibits contributions from the m-ethynylbenzyl and 1-phenylpropargyl radicals. The former, like PEB, is observed herein for the first time, and its identity is confirmed by measurement and calculation of its AIE and D0-D1 origin transition energy; the latter is identified by comparison with its known electronic spectrum (J. Am. Chem. Soc., 2008, 130, 3137-3142). Both species are found to co-exist with PEB at levels vastly greater than might be explained by any precursor sample impurity, implying that interconversion of ethynylbenzyl motifs is feasible in energetic environments such as plasmas and flames, wherein resonance-stabilized radicals are persistent.
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Affiliation(s)
- Sederra D Ross
- Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, Massachusetts 02125, United States
| | - Jonathan Flores
- Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, Massachusetts 02125, United States
| | - Sima Khani
- Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, Massachusetts 02125, United States
| | - Daniel M Hewett
- Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, Massachusetts 02125, United States
| | - Neil J Reilly
- Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, Massachusetts 02125, United States
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Kumar A, Rao TR, Sarkar R. An unbiased confirmation of the participating isomers of C 2B 5- in the formation of its photo-detachment spectra: a theoretical study. Phys Chem Chem Phys 2021; 23:3160-3175. [PMID: 33498079 DOI: 10.1039/d0cp04619a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The primary goal of the present article is to provide an unbiased structural confirmation of C2B5-, relying on its available experimental photo-detachment spectra. The study is performed from scratch by optimizing the lowest energy isomers of C2B5- and later, suitable molecular vibronic Hamiltonians are constructed by analyzing the normal modes of these optimized isomers. The Hamiltonians' parameters are evaluated from the fits of the calculated ab initio single point energies using a state of the art multireference configuration (MRCI) level of theory employing a correlation consistent polarized triple zeta (cc-pVTZ) basis set. The state-averaged variant of the MRCI level of theory is also applied to deal with the highly interactive electronic states of both of the isomers. A detailed analysis of the potential energy curves along the totally symmetric vibrational modes is performed to understand the energy modulation between the different electronic states and also to find the energetic locations of the conical intersections. The introduction of the non-symmetric vibrational modes in the Hamiltonians help to understand the impact of non-adiabaticity during energy modulation in the coupled surfaces. Later, both adiabatic and non-adiabatic nuclear dynamics are performed on the electronic states of both of the isomers using the constructed reduced and full-dimensional Hamiltonians. The results of the adiabatic dynamics are used to assign the positions of the simulated photo-detachment bands, while the non-adiabatic dynamics improve the shape of those bands. Finally, we compare our theoretical findings with the available experimental photo-detachment spectra of C2B5- to provide an unbiased structural confirmation of the participating isomers of C2B5- in its photo-detachment spectra.
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Affiliation(s)
- Abhishek Kumar
- Department of Chemistry, Indian Institute of Technology, Patna, Bihta, Bihar, 801103, India.
| | - T Rajagopala Rao
- Department of Chemistry, Indian Institute of Technology, Patna, Bihta, Bihar, 801103, India.
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