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John M. Dyke - One of the best experts on this subject based on the ideXlab platform.
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simulation of the single Vibronic Level emission spectra of haso and daso
Journal of Chemical Physics, 2016Co-Authors: Daniel K. W. Mok, Edmond P. F. Lee, John M. DykeAbstract:The single-Vibronic-Level (SVL) emission spectra of HAsO and DAsO have been simulated by electronic structure/Franck-Condon factor calculations to confirm the spectral molecular carrier and to investigate the electronic states involved. Various multi-reference (MR) methods, namely, NEVPT2 (n-electron valence state second order perturbation theory), RSPT2-F12 (explicitly correlated Rayleigh-Schrodinger second order perturbation theory), and MRCI-F12 (explicitly correlated multi-reference configuration interaction) were employed to compute the geometries and relative electronic energies for the X1A′ and A1A″ states of HAsO. These are the highest Level calculations on these states yet reported. The MRCI-F12 method gives computed T0 (adiabatic transition energy including zero-point energy correction) values, which agree well with the available experimental T0 value much better than previously computed values and values computed with other MR methods in this work. In addition, the potential energy surfaces of the X1A′ and A1A″ states of HAsO were computed using the MRCI-F12 method. Franck-Condon factors between the two states, which include anharmonicity and Duschinsky rotation, were then computed and used to simulate the recently reported SVL emission spectra of HAsO and DAsO [R. Grimminger and D. J. Clouthier, J. Chem. Phys. 135, 184308 (2011)]. Our simulated SVL emission spectra confirm the assignments of the molecular carrier, the electronic states involved, and the vibrational structures observed in the SVL emission spectra but suggest a loss of intensity in the reported experimental spectra at the low emission energy region almost certainly due to a loss of responsivity near the cutoff region (∼800 nm) of the detector used. Computed and experimentally derived re (equilibrium) and/or r0 {the (0,0,0) vibrational Level} geometries of the two states of HAsO are discussed.
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simulation of the single Vibronic Level emission spectrum of hps
Journal of Chemical Physics, 2014Co-Authors: Daniel K. W. Mok, Edmond P. F. Lee, Foo-tim Chau, John M. DykeAbstract:We have computed the potential energy surfaces of the X1A′ and A1A′′ states of HPS using the explicitly correlated multi-reference configuration interaction (MRCI-F12) method, and Franck–Condon factors between the two states, which include anharmonicity and Duschinsky rotation, with the aim of testing the assignment of the recently reported single-Vibronic-Level (SVL) emission spectrum of HPS [R. Grimminger, D. J. Clouthier, R. Tarroni, Z. Wang, and T. J. Sears, J. Chem. Phys. 139, 174306 (2013)]. These are the highest Level calculations on these states yet reported. It is concluded that our spectral simulation supports the assignments of the molecular carrier, the electronic states involved and the vibrational structure of the experimental laser induced fluorescence, and SVL emission spectra proposed by Grimminger et al. [J. Chem. Phys. 139, 174306 (2013)]. However, there remain questions unanswered regarding the relative electronic energies of the two states and the geometry of the excited state of HPS.
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ab initio calculations on the x 2 b1 and a 2 a1 states of ash2 and franck condon simulation including anharmonicity of the a 0 0 0 x single Vibronic Level emission spectrum of ash2
Journal of Chemical Physics, 2010Co-Authors: Edmond P. F. Lee, Daniel K. W. Mok, Foo-tim Chau, John M. DykeAbstract:Restricted-spin coupled-cluster single-double plus perturbative triple excitation {RCCSD(T)} calculations were carried out on the X (2)B(1) and A (2)A(1) states of AsH(2) employing the fully relativistic small-core effective core potential (ECP10MDF) for As and basis sets of up to the augmented correlation-consistent polarized valence quintuple-zeta (aug-cc-pV5Z) quality. Minimum-energy geometrical parameters and relative electronic energies were evaluated, including contributions from extrapolation to the complete basis set limit and from outer core correlation of the As 3d(10) electrons employing additional tight 4d3f2g2h functions designed for As. In addition, simplified, explicitly correlated CCSD(T)-F12 calculations were also performed employing different atomic orbital basis sets of up to aug-cc-pVQZ quality, and associated complementary auxiliary and density-fitting basis sets. The best theoretical estimate of the relative electronic energy of the A (2)A(1) state of AsH(2) relative to the X (2)B(1) state including zero-point energy correction (T(0)) is 19,954(32) cm(-1), which agrees very well with available experimental T(0) values of 19,909.4531(18) and 19,909.4910(17) cm(-1) obtained from recent laser induced fluorescence and cavity ringdown absorption spectroscopic studies. In addition, potential energy functions (PEFs) of the X (2)B(1) and A (2)A(1) states of AsH(2) were computed at different RCCSD(T) and CCSD(T)-F12 Levels. These PEFs were used in variational calculations of anharmonic vibrational wave functions, which were then utilized to calculate Franck-Condon factors (FCFs) between these two states, using a method which includes allowance for anharmonicity and Duschinsky rotation. The A(0,0,0)-X single Vibronic Level (SVL) emission spectrum of AsH(2) was simulated using these computed FCFs. Comparison between simulated and available experimental vibrationally resolved spectra of the A(0,0,0)-X SVL emission of AsH(2), which consist essentially of the bending (2(n)) series, suggests that there is a significant loss in intensity in the low emission energy region of the experimental spectrum.
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franck condon simulations including anharmonicity of the a 1 a x 1 a absorption and single Vibronic Level emission spectra of hsicl and dsicl
Journal of Chemical Theory and Computation, 2009Co-Authors: Daniel W K Mok, Edmond P. F. Lee, Foo-tim Chau, John M. DykeAbstract:RCCSD(T) and/or CASSCF/MRCI calculations have been carried out on the X(1)A' and A(1)A'' states of HSiCl employing basis sets of up to the aug-cc-pV5Z quality. Contributions from core correlation and extrapolation to the complete basis set limit were included in determining the computed equilibrium geometrical parameters and relative electronic energy of these two states of HSiCl. Franck-Condon factors which include allowance for anharmonicity and Duschinsky rotation between these two states of HSiCl and DSiCl were calculated employing RCCSD(T) and CASSCF/MRCI potential energy functions, and were used to simulate the A(1)A'' ← X(1)A' absorption and A(1)A'' → X(1)A' single Vibronic Level (SVL) emission spectra of HSiCl and DSiCl. Simulated absorption and experimental LIF spectra, and simulated and observed A(1)A''(0,0,0) → X(1)A' SVL emission spectra, of HSiCl and DSiCl are in very good agreement. However, agreement between simulated and observed A(1)A''(0,1,0) → X(1)A' and A(1)A''(0,2,1) → X(1)A' SVL emission spectra of DSiCl is not as good. Preliminary calculations on low-lying excited states of HSiCl suggest that Vibronic interaction between low-lying vibrational Levels of the A(1)A'' state and highly excited vibrational Levels of the a(3)A'' is possible. Such Vibronic interaction may change the character of the low-lying vibrational Levels of the A(1)A'' state, which would lead to perturbation in the SVL emission spectra from these vibrational Levels.
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condon simulation of the single Vibronic Level emission spectra of hpo and dpo
2009Co-Authors: Edmond P. F. Lee, Daniel K. W. Mok, Foo-tim Chau, John M. DykeAbstract:Minimum-energy geometries and relative electronic energies of the X A and A A states of HPO have been computed employing the coupled-cluster single-double plus perturbative triple excitations RCCSD T and/or complete-active-space self-consistent-field CASSCF multireference internally contracted configuration interaction MRCI methods with basis sets of up to the augmented correlation-consistent polarized-valence quintuple-zeta aug-cc-pV5Z quality. In addition, RCCSD T /aug-cc-pVQZ and CASSCF/MRCI/aug-cc-pVQZ potential energy functions, anharmonic vibrational wave functions, and energies involving all three vibrational modes for both electronic states of HPO and DPO, and Franck-Condon factors between the two electronic states, which allow for Duschinsky rotation and anharmonicity, were computed. Computed Franck-Condon factors were then used to simulate single Vibronic Level SVL emission spectra recently reported by Tackett and Clouthier J. Chem. Phys. 117, 10604 2002 . Excellent agreement between the simulated and observed spectra was obtained for the A A 1,0 ,0 → X A SVL emission of HPO and DPO, when the best estimated ab initio geometries of the two states, which include contributions from core correlation and extrapolation to the complete basis set limit, were used in the simulation, suggesting that the best estimated ab initio geometry of the A A state of HPO, particularly the bond angle of 94.5°, is more reliable than the available experimentally derived geometry. A discussion on the geometrical parameters derived from rotational constants obtained from the rotational analysis of a high-resolution spectrum and from Franck-Condon simulation of the vibrational structure of an electronic spectrum is given. © 2007 American Institute of Physics. DOI: 10.1063/1.2790892
Edmond P. F. Lee - One of the best experts on this subject based on the ideXlab platform.
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simulation of the single Vibronic Level emission spectra of haso and daso
Journal of Chemical Physics, 2016Co-Authors: Daniel K. W. Mok, Edmond P. F. Lee, John M. DykeAbstract:The single-Vibronic-Level (SVL) emission spectra of HAsO and DAsO have been simulated by electronic structure/Franck-Condon factor calculations to confirm the spectral molecular carrier and to investigate the electronic states involved. Various multi-reference (MR) methods, namely, NEVPT2 (n-electron valence state second order perturbation theory), RSPT2-F12 (explicitly correlated Rayleigh-Schrodinger second order perturbation theory), and MRCI-F12 (explicitly correlated multi-reference configuration interaction) were employed to compute the geometries and relative electronic energies for the X1A′ and A1A″ states of HAsO. These are the highest Level calculations on these states yet reported. The MRCI-F12 method gives computed T0 (adiabatic transition energy including zero-point energy correction) values, which agree well with the available experimental T0 value much better than previously computed values and values computed with other MR methods in this work. In addition, the potential energy surfaces of the X1A′ and A1A″ states of HAsO were computed using the MRCI-F12 method. Franck-Condon factors between the two states, which include anharmonicity and Duschinsky rotation, were then computed and used to simulate the recently reported SVL emission spectra of HAsO and DAsO [R. Grimminger and D. J. Clouthier, J. Chem. Phys. 135, 184308 (2011)]. Our simulated SVL emission spectra confirm the assignments of the molecular carrier, the electronic states involved, and the vibrational structures observed in the SVL emission spectra but suggest a loss of intensity in the reported experimental spectra at the low emission energy region almost certainly due to a loss of responsivity near the cutoff region (∼800 nm) of the detector used. Computed and experimentally derived re (equilibrium) and/or r0 {the (0,0,0) vibrational Level} geometries of the two states of HAsO are discussed.
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simulation of the single Vibronic Level emission spectrum of hps
Journal of Chemical Physics, 2014Co-Authors: Daniel K. W. Mok, Edmond P. F. Lee, Foo-tim Chau, John M. DykeAbstract:We have computed the potential energy surfaces of the X1A′ and A1A′′ states of HPS using the explicitly correlated multi-reference configuration interaction (MRCI-F12) method, and Franck–Condon factors between the two states, which include anharmonicity and Duschinsky rotation, with the aim of testing the assignment of the recently reported single-Vibronic-Level (SVL) emission spectrum of HPS [R. Grimminger, D. J. Clouthier, R. Tarroni, Z. Wang, and T. J. Sears, J. Chem. Phys. 139, 174306 (2013)]. These are the highest Level calculations on these states yet reported. It is concluded that our spectral simulation supports the assignments of the molecular carrier, the electronic states involved and the vibrational structure of the experimental laser induced fluorescence, and SVL emission spectra proposed by Grimminger et al. [J. Chem. Phys. 139, 174306 (2013)]. However, there remain questions unanswered regarding the relative electronic energies of the two states and the geometry of the excited state of HPS.
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ab initio calculations on the x 2 b1 and a 2 a1 states of ash2 and franck condon simulation including anharmonicity of the a 0 0 0 x single Vibronic Level emission spectrum of ash2
Journal of Chemical Physics, 2010Co-Authors: Edmond P. F. Lee, Daniel K. W. Mok, Foo-tim Chau, John M. DykeAbstract:Restricted-spin coupled-cluster single-double plus perturbative triple excitation {RCCSD(T)} calculations were carried out on the X (2)B(1) and A (2)A(1) states of AsH(2) employing the fully relativistic small-core effective core potential (ECP10MDF) for As and basis sets of up to the augmented correlation-consistent polarized valence quintuple-zeta (aug-cc-pV5Z) quality. Minimum-energy geometrical parameters and relative electronic energies were evaluated, including contributions from extrapolation to the complete basis set limit and from outer core correlation of the As 3d(10) electrons employing additional tight 4d3f2g2h functions designed for As. In addition, simplified, explicitly correlated CCSD(T)-F12 calculations were also performed employing different atomic orbital basis sets of up to aug-cc-pVQZ quality, and associated complementary auxiliary and density-fitting basis sets. The best theoretical estimate of the relative electronic energy of the A (2)A(1) state of AsH(2) relative to the X (2)B(1) state including zero-point energy correction (T(0)) is 19,954(32) cm(-1), which agrees very well with available experimental T(0) values of 19,909.4531(18) and 19,909.4910(17) cm(-1) obtained from recent laser induced fluorescence and cavity ringdown absorption spectroscopic studies. In addition, potential energy functions (PEFs) of the X (2)B(1) and A (2)A(1) states of AsH(2) were computed at different RCCSD(T) and CCSD(T)-F12 Levels. These PEFs were used in variational calculations of anharmonic vibrational wave functions, which were then utilized to calculate Franck-Condon factors (FCFs) between these two states, using a method which includes allowance for anharmonicity and Duschinsky rotation. The A(0,0,0)-X single Vibronic Level (SVL) emission spectrum of AsH(2) was simulated using these computed FCFs. Comparison between simulated and available experimental vibrationally resolved spectra of the A(0,0,0)-X SVL emission of AsH(2), which consist essentially of the bending (2(n)) series, suggests that there is a significant loss in intensity in the low emission energy region of the experimental spectrum.
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franck condon simulations including anharmonicity of the a 1 a x 1 a absorption and single Vibronic Level emission spectra of hsicl and dsicl
Journal of Chemical Theory and Computation, 2009Co-Authors: Daniel W K Mok, Edmond P. F. Lee, Foo-tim Chau, John M. DykeAbstract:RCCSD(T) and/or CASSCF/MRCI calculations have been carried out on the X(1)A' and A(1)A'' states of HSiCl employing basis sets of up to the aug-cc-pV5Z quality. Contributions from core correlation and extrapolation to the complete basis set limit were included in determining the computed equilibrium geometrical parameters and relative electronic energy of these two states of HSiCl. Franck-Condon factors which include allowance for anharmonicity and Duschinsky rotation between these two states of HSiCl and DSiCl were calculated employing RCCSD(T) and CASSCF/MRCI potential energy functions, and were used to simulate the A(1)A'' ← X(1)A' absorption and A(1)A'' → X(1)A' single Vibronic Level (SVL) emission spectra of HSiCl and DSiCl. Simulated absorption and experimental LIF spectra, and simulated and observed A(1)A''(0,0,0) → X(1)A' SVL emission spectra, of HSiCl and DSiCl are in very good agreement. However, agreement between simulated and observed A(1)A''(0,1,0) → X(1)A' and A(1)A''(0,2,1) → X(1)A' SVL emission spectra of DSiCl is not as good. Preliminary calculations on low-lying excited states of HSiCl suggest that Vibronic interaction between low-lying vibrational Levels of the A(1)A'' state and highly excited vibrational Levels of the a(3)A'' is possible. Such Vibronic interaction may change the character of the low-lying vibrational Levels of the A(1)A'' state, which would lead to perturbation in the SVL emission spectra from these vibrational Levels.
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condon simulation of the single Vibronic Level emission spectra of hpo and dpo
2009Co-Authors: Edmond P. F. Lee, Daniel K. W. Mok, Foo-tim Chau, John M. DykeAbstract:Minimum-energy geometries and relative electronic energies of the X A and A A states of HPO have been computed employing the coupled-cluster single-double plus perturbative triple excitations RCCSD T and/or complete-active-space self-consistent-field CASSCF multireference internally contracted configuration interaction MRCI methods with basis sets of up to the augmented correlation-consistent polarized-valence quintuple-zeta aug-cc-pV5Z quality. In addition, RCCSD T /aug-cc-pVQZ and CASSCF/MRCI/aug-cc-pVQZ potential energy functions, anharmonic vibrational wave functions, and energies involving all three vibrational modes for both electronic states of HPO and DPO, and Franck-Condon factors between the two electronic states, which allow for Duschinsky rotation and anharmonicity, were computed. Computed Franck-Condon factors were then used to simulate single Vibronic Level SVL emission spectra recently reported by Tackett and Clouthier J. Chem. Phys. 117, 10604 2002 . Excellent agreement between the simulated and observed spectra was obtained for the A A 1,0 ,0 → X A SVL emission of HPO and DPO, when the best estimated ab initio geometries of the two states, which include contributions from core correlation and extrapolation to the complete basis set limit, were used in the simulation, suggesting that the best estimated ab initio geometry of the A A state of HPO, particularly the bond angle of 94.5°, is more reliable than the available experimentally derived geometry. A discussion on the geometrical parameters derived from rotational constants obtained from the rotational analysis of a high-resolution spectrum and from Franck-Condon simulation of the vibrational structure of an electronic spectrum is given. © 2007 American Institute of Physics. DOI: 10.1063/1.2790892
Foo-tim Chau - One of the best experts on this subject based on the ideXlab platform.
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simulation of the single Vibronic Level emission spectrum of hps
Journal of Chemical Physics, 2014Co-Authors: Daniel K. W. Mok, Edmond P. F. Lee, Foo-tim Chau, John M. DykeAbstract:We have computed the potential energy surfaces of the X1A′ and A1A′′ states of HPS using the explicitly correlated multi-reference configuration interaction (MRCI-F12) method, and Franck–Condon factors between the two states, which include anharmonicity and Duschinsky rotation, with the aim of testing the assignment of the recently reported single-Vibronic-Level (SVL) emission spectrum of HPS [R. Grimminger, D. J. Clouthier, R. Tarroni, Z. Wang, and T. J. Sears, J. Chem. Phys. 139, 174306 (2013)]. These are the highest Level calculations on these states yet reported. It is concluded that our spectral simulation supports the assignments of the molecular carrier, the electronic states involved and the vibrational structure of the experimental laser induced fluorescence, and SVL emission spectra proposed by Grimminger et al. [J. Chem. Phys. 139, 174306 (2013)]. However, there remain questions unanswered regarding the relative electronic energies of the two states and the geometry of the excited state of HPS.
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ab initio calculations on the x 2 b1 and a 2 a1 states of ash2 and franck condon simulation including anharmonicity of the a 0 0 0 x single Vibronic Level emission spectrum of ash2
Journal of Chemical Physics, 2010Co-Authors: Edmond P. F. Lee, Daniel K. W. Mok, Foo-tim Chau, John M. DykeAbstract:Restricted-spin coupled-cluster single-double plus perturbative triple excitation {RCCSD(T)} calculations were carried out on the X (2)B(1) and A (2)A(1) states of AsH(2) employing the fully relativistic small-core effective core potential (ECP10MDF) for As and basis sets of up to the augmented correlation-consistent polarized valence quintuple-zeta (aug-cc-pV5Z) quality. Minimum-energy geometrical parameters and relative electronic energies were evaluated, including contributions from extrapolation to the complete basis set limit and from outer core correlation of the As 3d(10) electrons employing additional tight 4d3f2g2h functions designed for As. In addition, simplified, explicitly correlated CCSD(T)-F12 calculations were also performed employing different atomic orbital basis sets of up to aug-cc-pVQZ quality, and associated complementary auxiliary and density-fitting basis sets. The best theoretical estimate of the relative electronic energy of the A (2)A(1) state of AsH(2) relative to the X (2)B(1) state including zero-point energy correction (T(0)) is 19,954(32) cm(-1), which agrees very well with available experimental T(0) values of 19,909.4531(18) and 19,909.4910(17) cm(-1) obtained from recent laser induced fluorescence and cavity ringdown absorption spectroscopic studies. In addition, potential energy functions (PEFs) of the X (2)B(1) and A (2)A(1) states of AsH(2) were computed at different RCCSD(T) and CCSD(T)-F12 Levels. These PEFs were used in variational calculations of anharmonic vibrational wave functions, which were then utilized to calculate Franck-Condon factors (FCFs) between these two states, using a method which includes allowance for anharmonicity and Duschinsky rotation. The A(0,0,0)-X single Vibronic Level (SVL) emission spectrum of AsH(2) was simulated using these computed FCFs. Comparison between simulated and available experimental vibrationally resolved spectra of the A(0,0,0)-X SVL emission of AsH(2), which consist essentially of the bending (2(n)) series, suggests that there is a significant loss in intensity in the low emission energy region of the experimental spectrum.
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franck condon simulations including anharmonicity of the a 1 a x 1 a absorption and single Vibronic Level emission spectra of hsicl and dsicl
Journal of Chemical Theory and Computation, 2009Co-Authors: Daniel W K Mok, Edmond P. F. Lee, Foo-tim Chau, John M. DykeAbstract:RCCSD(T) and/or CASSCF/MRCI calculations have been carried out on the X(1)A' and A(1)A'' states of HSiCl employing basis sets of up to the aug-cc-pV5Z quality. Contributions from core correlation and extrapolation to the complete basis set limit were included in determining the computed equilibrium geometrical parameters and relative electronic energy of these two states of HSiCl. Franck-Condon factors which include allowance for anharmonicity and Duschinsky rotation between these two states of HSiCl and DSiCl were calculated employing RCCSD(T) and CASSCF/MRCI potential energy functions, and were used to simulate the A(1)A'' ← X(1)A' absorption and A(1)A'' → X(1)A' single Vibronic Level (SVL) emission spectra of HSiCl and DSiCl. Simulated absorption and experimental LIF spectra, and simulated and observed A(1)A''(0,0,0) → X(1)A' SVL emission spectra, of HSiCl and DSiCl are in very good agreement. However, agreement between simulated and observed A(1)A''(0,1,0) → X(1)A' and A(1)A''(0,2,1) → X(1)A' SVL emission spectra of DSiCl is not as good. Preliminary calculations on low-lying excited states of HSiCl suggest that Vibronic interaction between low-lying vibrational Levels of the A(1)A'' state and highly excited vibrational Levels of the a(3)A'' is possible. Such Vibronic interaction may change the character of the low-lying vibrational Levels of the A(1)A'' state, which would lead to perturbation in the SVL emission spectra from these vibrational Levels.
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condon simulation of the single Vibronic Level emission spectra of hpo and dpo
2009Co-Authors: Edmond P. F. Lee, Daniel K. W. Mok, Foo-tim Chau, John M. DykeAbstract:Minimum-energy geometries and relative electronic energies of the X A and A A states of HPO have been computed employing the coupled-cluster single-double plus perturbative triple excitations RCCSD T and/or complete-active-space self-consistent-field CASSCF multireference internally contracted configuration interaction MRCI methods with basis sets of up to the augmented correlation-consistent polarized-valence quintuple-zeta aug-cc-pV5Z quality. In addition, RCCSD T /aug-cc-pVQZ and CASSCF/MRCI/aug-cc-pVQZ potential energy functions, anharmonic vibrational wave functions, and energies involving all three vibrational modes for both electronic states of HPO and DPO, and Franck-Condon factors between the two electronic states, which allow for Duschinsky rotation and anharmonicity, were computed. Computed Franck-Condon factors were then used to simulate single Vibronic Level SVL emission spectra recently reported by Tackett and Clouthier J. Chem. Phys. 117, 10604 2002 . Excellent agreement between the simulated and observed spectra was obtained for the A A 1,0 ,0 → X A SVL emission of HPO and DPO, when the best estimated ab initio geometries of the two states, which include contributions from core correlation and extrapolation to the complete basis set limit, were used in the simulation, suggesting that the best estimated ab initio geometry of the A A state of HPO, particularly the bond angle of 94.5°, is more reliable than the available experimentally derived geometry. A discussion on the geometrical parameters derived from rotational constants obtained from the rotational analysis of a high-resolution spectrum and from Franck-Condon simulation of the vibrational structure of an electronic spectrum is given. © 2007 American Institute of Physics. DOI: 10.1063/1.2790892
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ab initio calculations on the x 1 a and a 1 a states of hpo and franck condon simulation of the single Vibronic Level emission spectra of hpo and dpo
Journal of Chemical Physics, 2007Co-Authors: Edmond P. F. Lee, Daniel K. W. Mok, Foo-tim Chau, John M. DykeAbstract:Minimum-energy geometries and relative electronic energies of the 1A and A 1A states of HPO have been computed employing the coupled-cluster single-double plus perturbative triple excitations {RCCSD(T)} and/or complete-active-space self-consistent-field (CASSCF) multireference internally contracted configuration interaction (MRCI) methods with basis sets of up to the augmented correlation-consistent polarized-valence quintuple-zeta (aug-cc-pV5Z) quality. In addition, RCCSD(T)/aug-cc-pVQZ and CASSCF/MRCI/aug-cc-pVQZ potential energy functions, anharmonic vibrational wave functions, and energies involving all three vibrational modes for both electronic states of HPO and DPO, and Franck-Condon factors between the two electronic states, which allow for Duschinsky rotation and anharmonicity, were computed. Computed Franck-Condon factors were then used to simulate single Vibronic Level (SVL) emission spectra recently reported by Tackett and Clouthier [J. Chem. Phys. 117, 10604 (2002)]. Excellent agreement between the simulated and observed spectra was obtained for the A 1A(1,0,0) 1A SVL emission of HPO and DPO, when the best estimated ab initio geometries of the two states, which include contributions from core correlation and extrapolation to the complete basis set limit, were used in the simulation, suggesting that the best estimated ab initio geometry of the A 1A state of HPO, particularly the bond angle of 94.5°, is more reliable than the available experimentally derived geometry. A discussion on the geometrical parameters derived from rotational constants obtained from the rotational analysis of a high-resolution spectrum and from Franck-Condon simulation of the vibrational structure of an electronic spectrum is given.
Daniel K. W. Mok - One of the best experts on this subject based on the ideXlab platform.
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simulation of the single Vibronic Level emission spectra of haso and daso
Journal of Chemical Physics, 2016Co-Authors: Daniel K. W. Mok, Edmond P. F. Lee, John M. DykeAbstract:The single-Vibronic-Level (SVL) emission spectra of HAsO and DAsO have been simulated by electronic structure/Franck-Condon factor calculations to confirm the spectral molecular carrier and to investigate the electronic states involved. Various multi-reference (MR) methods, namely, NEVPT2 (n-electron valence state second order perturbation theory), RSPT2-F12 (explicitly correlated Rayleigh-Schrodinger second order perturbation theory), and MRCI-F12 (explicitly correlated multi-reference configuration interaction) were employed to compute the geometries and relative electronic energies for the X1A′ and A1A″ states of HAsO. These are the highest Level calculations on these states yet reported. The MRCI-F12 method gives computed T0 (adiabatic transition energy including zero-point energy correction) values, which agree well with the available experimental T0 value much better than previously computed values and values computed with other MR methods in this work. In addition, the potential energy surfaces of the X1A′ and A1A″ states of HAsO were computed using the MRCI-F12 method. Franck-Condon factors between the two states, which include anharmonicity and Duschinsky rotation, were then computed and used to simulate the recently reported SVL emission spectra of HAsO and DAsO [R. Grimminger and D. J. Clouthier, J. Chem. Phys. 135, 184308 (2011)]. Our simulated SVL emission spectra confirm the assignments of the molecular carrier, the electronic states involved, and the vibrational structures observed in the SVL emission spectra but suggest a loss of intensity in the reported experimental spectra at the low emission energy region almost certainly due to a loss of responsivity near the cutoff region (∼800 nm) of the detector used. Computed and experimentally derived re (equilibrium) and/or r0 {the (0,0,0) vibrational Level} geometries of the two states of HAsO are discussed.
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simulation of the single Vibronic Level emission spectrum of hps
Journal of Chemical Physics, 2014Co-Authors: Daniel K. W. Mok, Edmond P. F. Lee, Foo-tim Chau, John M. DykeAbstract:We have computed the potential energy surfaces of the X1A′ and A1A′′ states of HPS using the explicitly correlated multi-reference configuration interaction (MRCI-F12) method, and Franck–Condon factors between the two states, which include anharmonicity and Duschinsky rotation, with the aim of testing the assignment of the recently reported single-Vibronic-Level (SVL) emission spectrum of HPS [R. Grimminger, D. J. Clouthier, R. Tarroni, Z. Wang, and T. J. Sears, J. Chem. Phys. 139, 174306 (2013)]. These are the highest Level calculations on these states yet reported. It is concluded that our spectral simulation supports the assignments of the molecular carrier, the electronic states involved and the vibrational structure of the experimental laser induced fluorescence, and SVL emission spectra proposed by Grimminger et al. [J. Chem. Phys. 139, 174306 (2013)]. However, there remain questions unanswered regarding the relative electronic energies of the two states and the geometry of the excited state of HPS.
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ab initio calculations on the x 2 b1 and a 2 a1 states of ash2 and franck condon simulation including anharmonicity of the a 0 0 0 x single Vibronic Level emission spectrum of ash2
Journal of Chemical Physics, 2010Co-Authors: Edmond P. F. Lee, Daniel K. W. Mok, Foo-tim Chau, John M. DykeAbstract:Restricted-spin coupled-cluster single-double plus perturbative triple excitation {RCCSD(T)} calculations were carried out on the X (2)B(1) and A (2)A(1) states of AsH(2) employing the fully relativistic small-core effective core potential (ECP10MDF) for As and basis sets of up to the augmented correlation-consistent polarized valence quintuple-zeta (aug-cc-pV5Z) quality. Minimum-energy geometrical parameters and relative electronic energies were evaluated, including contributions from extrapolation to the complete basis set limit and from outer core correlation of the As 3d(10) electrons employing additional tight 4d3f2g2h functions designed for As. In addition, simplified, explicitly correlated CCSD(T)-F12 calculations were also performed employing different atomic orbital basis sets of up to aug-cc-pVQZ quality, and associated complementary auxiliary and density-fitting basis sets. The best theoretical estimate of the relative electronic energy of the A (2)A(1) state of AsH(2) relative to the X (2)B(1) state including zero-point energy correction (T(0)) is 19,954(32) cm(-1), which agrees very well with available experimental T(0) values of 19,909.4531(18) and 19,909.4910(17) cm(-1) obtained from recent laser induced fluorescence and cavity ringdown absorption spectroscopic studies. In addition, potential energy functions (PEFs) of the X (2)B(1) and A (2)A(1) states of AsH(2) were computed at different RCCSD(T) and CCSD(T)-F12 Levels. These PEFs were used in variational calculations of anharmonic vibrational wave functions, which were then utilized to calculate Franck-Condon factors (FCFs) between these two states, using a method which includes allowance for anharmonicity and Duschinsky rotation. The A(0,0,0)-X single Vibronic Level (SVL) emission spectrum of AsH(2) was simulated using these computed FCFs. Comparison between simulated and available experimental vibrationally resolved spectra of the A(0,0,0)-X SVL emission of AsH(2), which consist essentially of the bending (2(n)) series, suggests that there is a significant loss in intensity in the low emission energy region of the experimental spectrum.
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condon simulation of the single Vibronic Level emission spectra of hpo and dpo
2009Co-Authors: Edmond P. F. Lee, Daniel K. W. Mok, Foo-tim Chau, John M. DykeAbstract:Minimum-energy geometries and relative electronic energies of the X A and A A states of HPO have been computed employing the coupled-cluster single-double plus perturbative triple excitations RCCSD T and/or complete-active-space self-consistent-field CASSCF multireference internally contracted configuration interaction MRCI methods with basis sets of up to the augmented correlation-consistent polarized-valence quintuple-zeta aug-cc-pV5Z quality. In addition, RCCSD T /aug-cc-pVQZ and CASSCF/MRCI/aug-cc-pVQZ potential energy functions, anharmonic vibrational wave functions, and energies involving all three vibrational modes for both electronic states of HPO and DPO, and Franck-Condon factors between the two electronic states, which allow for Duschinsky rotation and anharmonicity, were computed. Computed Franck-Condon factors were then used to simulate single Vibronic Level SVL emission spectra recently reported by Tackett and Clouthier J. Chem. Phys. 117, 10604 2002 . Excellent agreement between the simulated and observed spectra was obtained for the A A 1,0 ,0 → X A SVL emission of HPO and DPO, when the best estimated ab initio geometries of the two states, which include contributions from core correlation and extrapolation to the complete basis set limit, were used in the simulation, suggesting that the best estimated ab initio geometry of the A A state of HPO, particularly the bond angle of 94.5°, is more reliable than the available experimentally derived geometry. A discussion on the geometrical parameters derived from rotational constants obtained from the rotational analysis of a high-resolution spectrum and from Franck-Condon simulation of the vibrational structure of an electronic spectrum is given. © 2007 American Institute of Physics. DOI: 10.1063/1.2790892
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ab initio calculations on the x 1 a and a 1 a states of hpo and franck condon simulation of the single Vibronic Level emission spectra of hpo and dpo
Journal of Chemical Physics, 2007Co-Authors: Edmond P. F. Lee, Daniel K. W. Mok, Foo-tim Chau, John M. DykeAbstract:Minimum-energy geometries and relative electronic energies of the 1A and A 1A states of HPO have been computed employing the coupled-cluster single-double plus perturbative triple excitations {RCCSD(T)} and/or complete-active-space self-consistent-field (CASSCF) multireference internally contracted configuration interaction (MRCI) methods with basis sets of up to the augmented correlation-consistent polarized-valence quintuple-zeta (aug-cc-pV5Z) quality. In addition, RCCSD(T)/aug-cc-pVQZ and CASSCF/MRCI/aug-cc-pVQZ potential energy functions, anharmonic vibrational wave functions, and energies involving all three vibrational modes for both electronic states of HPO and DPO, and Franck-Condon factors between the two electronic states, which allow for Duschinsky rotation and anharmonicity, were computed. Computed Franck-Condon factors were then used to simulate single Vibronic Level (SVL) emission spectra recently reported by Tackett and Clouthier [J. Chem. Phys. 117, 10604 (2002)]. Excellent agreement between the simulated and observed spectra was obtained for the A 1A(1,0,0) 1A SVL emission of HPO and DPO, when the best estimated ab initio geometries of the two states, which include contributions from core correlation and extrapolation to the complete basis set limit, were used in the simulation, suggesting that the best estimated ab initio geometry of the A 1A state of HPO, particularly the bond angle of 94.5°, is more reliable than the available experimentally derived geometry. A discussion on the geometrical parameters derived from rotational constants obtained from the rotational analysis of a high-resolution spectrum and from Franck-Condon simulation of the vibrational structure of an electronic spectrum is given.
Dennis J Clouthier - One of the best experts on this subject based on the ideXlab platform.
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detection and characterization of the tin dihydride snh2 and snd2 molecule in the gas phase
Journal of Chemical Physics, 2018Co-Authors: Tony C Smith, Dennis J ClouthierAbstract:The SnH2 and SnD2 molecules have been detected for the first time in the gas phase by laser-induced fluorescence (LIF) and emission spectroscopic techniques through the A1B1–X1A1 electronic transition. These reactive species were prepared in a pulsed electric discharge jet using (CH3)4Sn or SnH4/SnD4 precursors diluted in high pressure argon. Transitions to the electronic excited state of the jet-cooled molecules were probed with LIF, and the ground state energy Levels were measured from single roVibronic Level emission spectra. The LIF spectrum of SnD2 afforded sufficient rotational structure to determine the ground and excited state geometries: r0″ = 1.768 A, θ0″ = 91.0°, r0′ = 1.729 A, θ0′ = 122.9°. All of the observed LIF bands show evidence of a rotational-Level-dependent predissociation process which rapidly decreases the fluorescence yield and lifetime with increasing rotational angular momentum in each excited Vibronic Level. This behavior is analogous to that observed in SiH2 and GeH2 and is sug...
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applied quantum chemistry spectroscopic detection and characterization of the f2bs and cl2bs free radicals in the gas phase
Journal of Chemical Physics, 2015Co-Authors: Bing Jin, Phillip M Sheridan, Dennis J ClouthierAbstract:In this and previous work [D. J. Clouthier, J. Chem. Phys. 141, 244309 (2014)], the spectroscopic signatures of the X2BY (X = H, halogen, Y = O, S) free radicals have been predicted using high Level ab initio theory. The theoretical results have been used to calculate the electronic absorption and single Vibronic Level (SVL) emission spectra of the radicals under typical jet-cooled conditions. Using these diagnostic predictions, the previously unknown F2BS and Cl2BS free radicals have been identified and characterized. The radicals were prepared in a free jet expansion by subjecting precursor mixtures of BF3 or BCl3 and CS2 vapor to an electric discharge at the exit of a pulsed molecular beam valve. The B2A1–X2B2 laser-induced fluorescence spectra were found within 150 cm−1 of their theoretically predicted positions with Vibronic structure consistent with our Franck-Condon simulations. The B2A1 state emits down to the ground state and to the low-lying A2B1 excited state and the correspondence between ...
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the electronic spectrum of the fluoroborane free radical ii analysis of laser induced fluorescence and single Vibronic Level emission spectra
Journal of Chemical Physics, 2009Co-Authors: Fumie X Sunahori, Dennis J ClouthierAbstract:Subsequent to our spectroscopic detection of the HBX (X=F, Cl, Br) free radicals (S.-G. He, F. X. Sunahori, and D. J. Clouthier, J. Am. Chem. Soc. 127, 10814 (2005)), the electronic spectrum of the A A2″Π-X A2′ system of the fluoroborane (HBF) radical in the 600–745 nm region has been studied in detail using the pulsed discharge jet technique. The band system involves a linear-bent transition between the two Renner–Teller components of what would be a Π2 state at linearity. Using the results of our theoretical study of the ground and excited state vibrational energy Levels and B11–B10 isotope shifts (see the companion paper), the vibrational quantum numbers of the bands in the laser-induced fluorescence (LIF) spectra have been assigned. Rotational and vibrational analyses of the LIF and wavelength resolved emission spectra have been carried out, from which the linear excited state and the bent ground state equilibrium configurations have been confirmed. The ground state molecular geometry of HBF has bee...
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single Vibronic Level emission spectroscopic studies of the ground state energy Levels and molecular structures of jet cooled hgebr dgebr hgei and dgei
Journal of Chemical Physics, 2006Co-Authors: Brandon S Tackett, Dennis J Clouthier, Kezia L Pacheco, Alan G Schick, R. H. JudgeAbstract:Single Vibronic Level dispersed fluorescence spectra of jet-cooled HGeBr, DGeBr, HGeI, and DGeI have been obtained by laser excitation of selected bands of the AA″1-XA′1 electronic transition. The measured ground state vibrational intervals were assigned and fitted to anharmonicity expressions, which allowed the harmonic frequencies to be determined for both isotopomers. In some cases, lack of a suitable range of emission data necessitated that some of the anharmonicity constants and vibrational frequencies be estimated from those of HGeCl∕DGeCl and the corresponding silylenes (HSiX). Harmonic force fields were obtained for both molecules, although only four of the six force constants could be determined. The ground state effective rotational constants and force field data were combined to calculate average (rz) and approximate equilibrium (rez) structures. For HGeBr rez(GeH)=1.593(9)A, rez(GeBr)=2.325(21)A, and the bond angle was fixed at our CCSD(T)/aug-cc-pVTZ ab initio value of 93.6°. For HGeI we ob...
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the ground state energy Levels and molecular structure of jet cooled hgecl and dgecl from single Vibronic Level emission spectroscopy
Journal of Chemical Physics, 2006Co-Authors: Brandon S Tackett, Dennis J Clouthier, Kezia L Pacheco, Alan G SchickAbstract:Single Vibronic Level dispersed fluorescence spectra of jet-cooled HGeCl and DGeCl have been recorded by laser excitation of selected bands of the AA″1–XA′1 electronic transition. Twenty-six ground state vibrational Levels of HGeCl and 42 of DGeCl were measured, assigned, and fitted to standard anharmonicity expressions, which allowed all the harmonic frequencies to be determined for both isotopomers. A normal coordinate least squares analysis obtained by fitting the harmonic frequencies yielded reliable values for five of the six force constants. The ground state effective rotational constants and force field data were combined to calculate average (rz) and approximate equilibrium (rez) structures, with rez(GeH)=1.586(1)A, rez(GeCl)=2.171(2)A, and the bond angle fixed at our CCSD(T)/aug-cc-pVTZ ab initio value of 93.9°. Comparisons show that the derived bond lengths are consistent with those of the appropriate diatomic molecules in their ground electronic states and the bond angle is similar to that of...
