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Telfah H, Sharma K, Paul AC, Riyadh SMS, Miller TA, Liu J. A combined experimental and computational study on the transition of the calcium isopropoxide radical as a candidate for direct laser cooling. Phys Chem Chem Phys 2022; 24:8749-8762. [PMID: 35352070 DOI: 10.1039/d1cp04107j] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Vibronically resolved laser-induced fluorescence/dispersed fluorescence (LIF/DF) and cavity ring-down (CRD) spectra of the electronic transition of the calcium isopropoxide [CaOCH(CH3)2] radical have been obtained under jet-cooled conditions. An essentially constant energy separation of 68 cm-1 has been observed for the vibrational ground levels and all fundamental vibrational levels accessed in the LIF measurement. To simulate the experimental spectra and assign the recorded vibronic bands, Franck-Condon (FC) factors and vibrational branching ratios (VBRs) are predicted from vibrational modes and their frequencies calculated using the complete-active-space self-consistent field (CASSCF) and equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) methods. Combined with the calculated electronic transition energy, the computational results, especially those from the EOM-CCSD calculations, reproduced the experimental spectra with considerable accuracy. The experimental and computational results suggest that the FC matrix for the studied electronic transition is largely diagonal, but transitions from the vibrationless levels of the à state to the X̃-state levels of the CCC bending (ν14 and ν15), CaO stretch (ν13), and CaOC asymmetric stretch (ν9 and ν11) modes also have considerable intensities. Transitions to low-frequency in-plane [ν17(a')] and out-of-plane [ν30(a'')] CaOC bending modes were observed in the experimental LIF/DF spectra, the latter being FC-forbidden but induced by the pseudo-Jahn-Teller (pJT) effect. Both bending modes are coupled to the CaOC asymmetric stretch mode via the Duschinsky rotation, as demonstrated in the DF spectra obtained by pumping non-origin vibronic transitions. The pJT interaction also induces transitions to the ground-state vibrational level of the ν10(a') mode, which has the CaOC bending character. Our combined experimental and computational results provide critical information for future direct laser cooling of the target molecule and other alkaline earth monoalkoxide radicals.
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Affiliation(s)
- Hamzeh Telfah
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
| | - Ketan Sharma
- Department of Chemistry, The Ohio State University, Columbus, Ohio 43210, USA
| | - Anam C Paul
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
| | - S M Shah Riyadh
- Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40292, USA
| | - Terry A Miller
- Department of Chemistry, The Ohio State University, Columbus, Ohio 43210, USA
| | - Jinjun Liu
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA. .,Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40292, USA
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Shen Y, Yarkony DR. Unified Description of the Jahn-Teller Effect in Molecules with Only C s Symmetry: Cyclohexoxy in Its Full 48-Dimensional Internal Coordinates. J Phys Chem A 2021; 126:61-67. [PMID: 34965116 DOI: 10.1021/acs.jpca.1c09123] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The two lowest potential energy surfaces of cyclohexoxy which are coupled by conical intersections and the spin-orbit interaction are determined in the full 48-dimensional internal coordinate space using a feedforward neural network to fit a diabatic potential energy matrix. The electronic structure data are obtained at the multireference configuration interaction with single- and double-excitation level. Underlying parallels between these coupled surfaces and those of the alkoxy radicals methoxy and isopropoxy are established. Earlier work by Dillon and Yarkony is extended. While the parallels would have been challenging to appreciate using the concept of the Jahn-Teller active modes, they are readily seen in terms of two internal modes centered at the conical intersection: g the energy difference gradient vector and h the interstate coupling gradient vector. In other words, g and h vectors provide a unified description of the Jahn-Teller effect in molecules exhibiting C3v and quasi-C3v symmetries. A spectral simulation in the full 48-vibrational-internal coordinate space is reported. This spectrum is obtained using recently developed algorithms designed to increase the size of the systems that can be treated with a time-independent vibronic coupling approach.
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Affiliation(s)
- Yifan Shen
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David R Yarkony
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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Shen Y, Yarkony DR. Compact Bases for Vibronic Coupling in Spectral Simulations: The Photoelectron Spectrum of Cyclopentoxide in the Full 39 Internal Modes. J Phys Chem Lett 2020; 11:7245-7252. [PMID: 32787311 DOI: 10.1021/acs.jpclett.0c02199] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report an algorithm to automatically generate compact multimode vibrational bases for the Köppel-Domcke-Cederbaum (KDC) vibronic coupling wave function used in spectral simulations of moderate-sized molecules. As a full quantum method, the size of the vibronic expansion grows exponentially with respect to the number of vibrational modes, necessitating compact bases for moderate-sized systems. The problem of generating such a basis consists of two parts: one is the choice of vibrational normal modes, and the other is the number of phonons allowed in each mode. A previously developed final-state-biased technique addresses the former part, and this work focuses on the latter part: proposing an algorithm for generating an optimal phonon distribution. By virtue of this phonon distribution, compact and affordable bases can be automatically generated for systems with on the order of 15 atoms. Our algorithm is applied to determine the nonadiabatic photoelectron spectrum of cyclopentoxide in the full 39 internal modes.
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Affiliation(s)
- Yifan Shen
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David R Yarkony
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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Sullivan EN, Saric S, Neumark DM. Photodissociation of iso-propoxy (i-C 3H 7O) radical at 248 nm. Phys Chem Chem Phys 2020; 22:17738-17748. [DOI: 10.1039/d0cp02493g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photodissociation of the i-C3H7O radical is investigated using fast beam photofragment translational spectroscopy.
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Affiliation(s)
- Erin N. Sullivan
- Department of Chemistry
- University of California
- Berkeley
- USA
- Chemical Sciences Division
| | - Steven Saric
- Department of Chemistry
- University of California
- Berkeley
- USA
- Chemical Sciences Division
| | - Daniel M. Neumark
- Department of Chemistry
- University of California
- Berkeley
- USA
- Chemical Sciences Division
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Belcher LT, Kedziora GS, Weeks DE. Analytic non-adiabatic derivative coupling terms for spin-orbit MRCI wavefunctions. I. Formalism. J Chem Phys 2019; 151:234104. [PMID: 31864254 DOI: 10.1063/1.5126800] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Analytic gradients of electronic eigenvalues require one calculation per nuclear geometry, compared to at least 3n + 1 calculations for finite difference methods, where n is the number of nuclei. Analytic nonadiabatic derivative coupling terms (DCTs), which are calculated in a similar fashion, are used to remove nondiagonal contributions to the kinetic energy operator, leading to more accurate nuclear dynamics calculations than those that employ the Born-Oppenheimer approximation, i.e., that assume off-diagonal contributions are zero. The current methods and underpinnings for calculating both of these quantities, gradients and DCTs, for the State-Averaged MultiReference Configuration Interaction with Singles and Doubles (MRCI-SD) wavefunctions in COLUMBUS are reviewed. Before this work, these methods were not available for wavefunctions of a relativistic MRCI-SD Hamiltonian. Calculation of these terms is critical in successfully modeling the dynamics of systems that depend on transitions between potential energy surfaces split by the spin-orbit operator, such as diode-pumped alkali lasers. A formalism for calculating the transition density matrices and analytic derivative coupling terms for such systems is presented.
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Affiliation(s)
- Lachlan T Belcher
- Laser and Optics Research Center, Department of Physics, US Air Force Academy, Colorado Springs, Colorado 80840, USA
| | - Gary S Kedziora
- HPCMP PETTT/SAIC, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, USA
| | - David E Weeks
- Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson AFB, Ohio 45433, USA
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Oliveira AM, Lehman JH, Lineberger WC. Photoelectron Spectroscopy of the Aminomethoxide Anion, H 2C(NH 2)O –. J Phys Chem A 2018; 122:4954-4962. [DOI: 10.1021/acs.jpca.8b02921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Allan M. Oliveira
- JILA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Julia H. Lehman
- JILA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - W. Carl Lineberger
- JILA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
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Oliveira AM, Lehman JH, McCoy AB, Lineberger WC. Photoelectron spectroscopy of the hydroxymethoxide anion, H 2C(OH)O . J Chem Phys 2016; 145:124317. [PMID: 27782682 DOI: 10.1063/1.4963225] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report the negative ion photoelectron spectroscopy of the hydroxymethoxide anion, H2C(OH)O-. The photoelectron spectra show that 3.49 eV photodetachment produces two distinct electronic states of the neutral hydroxymethoxy radical (H2C(OH)O⋅). The H2C(OH)O⋅ ground state (X̃ 2A) photoelectron spectrum exhibits a vibrational progression consisting primarily of the OCO symmetric and asymmetric stretches, the OCO bend, as well as combination bands involving these modes with other, lower frequency modes. A high-resolution photoelectron spectrum aids in the assignment of several vibrational frequencies of the neutral H2C(OH)O⋅ radical, including an experimental determination of the H2C(OH)O⋅ 2ν12 overtone of the H-OCO torsional vibration as 220(10) cm-1. The electron affinity of H2C(OH)O⋅ is determined to be 2.220(2) eV. The low-lying à 2A excited state is also observed, with a spectrum that peaks ∼0.8 eV above the X̃ 2A state origin. The à 2A state photoelectron spectrum is a broad, partially resolved band. Quantum chemical calculations and photoelectron simulations aid in the interpretation of the photoelectron spectra. In addition, the gas phase acidity of methanediol is calculated to be 366(2) kcal mol-1, which results in an OH bond dissociation energy, D0(H2C(OH)O-H), of 104(2) kcal mol-1, using the experimentally determined electron affinity of the hydroxymethoxy radical.
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Affiliation(s)
- Allan M Oliveira
- JILA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA
| | - Julia H Lehman
- JILA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA
| | - Anne B McCoy
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - W Carl Lineberger
- JILA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA
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Affiliation(s)
- Xiaolei Zhu
- Department of Chemistry, Johns Hopkins University Baltimore, MD, USA
| | - David R. Yarkony
- Department of Chemistry, Johns Hopkins University Baltimore, MD, USA
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Alam J, Reza MA, Mason A, Reilly NJ, Liu J. Dispersed Fluorescence Spectroscopy of Jet-Cooled 2-, 3-, and 4-Methylcyclohexoxy Radicals. J Phys Chem A 2015; 119:6257-68. [PMID: 26016956 DOI: 10.1021/acs.jpca.5b03454] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Vibrational structures of the nearly degenerate X̃ and à states of the 2-, 3-, and 4-methylcyclohexoxy (MCHO) radicals were studied by jet-cooled dispersed fluorescence (DF) spectroscopy. The observed transitions were assigned on the basis of vibrational frequencies and Franck-Condon factors predicted by quantum chemical calculations. Intensities of vibronic transitions in the DF spectra are dependent on the laser-induced fluorescence (LIF) bands pumped in the experiment, which can be explained by the difference in geometry and symmetry between the lower X̃/à states and the highly excited B̃ state. All three studied isomers of MCHO have close-lying X̃ and à states although their energy separations are affected by the position of the methyl group. It is suggested by quantum chemical calculations that the lowest-energy conformers of all three isomers have the half-filled orbital oriented perpendicular to the OCH plane, which is consistent with the observed relative intensities of the B̃ → X̃ and B̃ → à origin bands. When the origin and the CO-stretch bands of the B̃ ← X̃ LIF excitation spectra were pumped, the DF spectra were dominated by CO-stretch progressions. When non-CO-stretch vibrational levels of the B̃ state were pumped, progressions of CO-stretch modes combined with the pumped vibrational mode were observed. Excited-state vibrational population relaxation from the CO stretch level to the vibrational ground level and from combination levels of the CO stretch mode and other vibrational modes to the non-CO stretch modes was observed. Analysis of the DF spectra confirms the previous conclusion that all strong LIF bands observed under jet-cooled conditions belong to a single conformer of each positional isomer (Lin et al. RSC Adv. 2012, 2, 583-589).
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Affiliation(s)
- Jahangir Alam
- †Department of Chemistry and ‡Conn Center for Renewable Energy Research, University of Louisville, Louisville, Kentucky 40292, United States
| | - Md Asmaul Reza
- †Department of Chemistry and ‡Conn Center for Renewable Energy Research, University of Louisville, Louisville, Kentucky 40292, United States
| | - Amy Mason
- †Department of Chemistry and ‡Conn Center for Renewable Energy Research, University of Louisville, Louisville, Kentucky 40292, United States
| | - Neil J Reilly
- †Department of Chemistry and ‡Conn Center for Renewable Energy Research, University of Louisville, Louisville, Kentucky 40292, United States
| | - Jinjun Liu
- †Department of Chemistry and ‡Conn Center for Renewable Energy Research, University of Louisville, Louisville, Kentucky 40292, United States
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Chhantyal-Pun R, Roudjane M, Melnik DG, Miller TA, Liu J. Jet-cooled laser-induced fluorescence spectroscopy of isopropoxy radical: vibronic analysis of B̃-X̃ and B̃-Ã band systems. J Phys Chem A 2014; 118:11852-70. [PMID: 25054866 DOI: 10.1021/jp504322j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recently we published [ Liu et al. J. Chem. Phys. 2013 , 139 , 154312 ] an analysis of the rotational structure of the B̃-X̃ origin band spectrum of isopropoxy, which confirmed that the double methyl substitution of methoxy to yield the isopropoxy radical only slightly lifted the degeneracy of the former's X̃(2)E state. Additionally the spectral results provided considerable insight into the relativistic and nonrelativistic contributions to the experimental splitting between the components of the (2)E state. However, left unexplained was how the Jahn-Teller (JT) vibronic coupling terms within methoxy's (2)E state manifest themselves as pseudo-Jahn-Teller (pJT) vibronic coupling between the Ã(2)A″ and X̃(2)A' levels of isopropoxy. To cast additional light on this subject we have obtained new isopropoxy spectra and assigned a number of weak, "forbidden" vibronic transitions in the B̃-X̃ spectrum using new electronic structure calculations and rotational contour analyses. The mechanisms that provide the nonzero probability for these transitions shed considerable information on pJT, spin-orbit, and Coriolis coupling between the à and X̃ states. We also report a novel mechanism caused by pJT coupling that yields excitation probability to the B̃ state dependent upon the permanent dipole moments in the B̃ and à or X̃ states. By combining a new B̃-à and the earlier B̃-X̃ rotational analyses we determine a much improved value for the experimental Ã-X̃ separation.
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Affiliation(s)
- Rabi Chhantyal-Pun
- Laser Spectroscopy Facility, Department of Chemistry and Biochemistry, The Ohio State University , 120 West 18th Avenue, Columbus, Ohio 43210, United States
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Liu J, Miller TA. Jet-Cooled Laser-Induced Fluorescence Spectroscopy of Cyclohexoxy: Rotational and Fine Structure of Molecules in Nearly Degenerate Electronic States. J Phys Chem A 2014; 118:11871-90. [DOI: 10.1021/jp504326p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jinjun Liu
- Department
of Chemistry and Conn Center for Renewable Energy Research, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292, United States, and
| | - Terry A. Miller
- Laser
Spectroscopy Facility, Department of Chemistry and Biochemistry, The Ohio State University, 120 West 18th Avenue, Columbus Ohio 43210, United States
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Liu J, Melnik D, Miller TA. Rotationally resolved B̃←X̃ electronic spectra of the isopropoxy radical: A comparative study. J Chem Phys 2013; 139:094308. [DOI: 10.1063/1.4819343] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Dillon J, Yarkony DR. Nonadiabatic effects in substitutional isomers of Jahn-Teller molecules: The strange case of hydroxymethoxy. J Chem Phys 2012; 137:154315. [DOI: 10.1063/1.4757727] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Domcke W, Yarkony DR. Role of Conical Intersections in Molecular Spectroscopy and Photoinduced Chemical Dynamics. Annu Rev Phys Chem 2012; 63:325-52. [DOI: 10.1146/annurev-physchem-032210-103522] [Citation(s) in RCA: 355] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Wolfgang Domcke
- Department of Chemistry, Technical University of Munich, D-85747 Garching, Germany
| | - David R. Yarkony
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218; ,
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Affiliation(s)
- David R. Yarkony
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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Dillon J, Yarkony DR, Schuurman MS. On the simulation of photoelectron spectra complicated by conical intersections: Higher-order effects and hot bands in the photoelectron spectrum of triazolide (CH)2N3−. J Chem Phys 2011; 134:184314. [DOI: 10.1063/1.3587094] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Han S, Yarkony DR. On the determination of intensities for electron photodetachment and photoionization spectra involving states coupled by conical intersections: Total integral cross sections for polyatomic molecules. J Chem Phys 2010; 133:194107. [DOI: 10.1063/1.3503166] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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Dillon JJ, Yarkony DR. The photoelectron spectrum of the ethoxide anion: Conical intersections, the spin-orbit interaction, and sequence bands. J Chem Phys 2009; 131:134303. [DOI: 10.1063/1.3238155] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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