A new graphical version of STROTAB: The analysis and fitting of singlet–triplet spectra of asymmetric top molecules in the prolate or oblate limits

Kodet, John G.; Judge, R. H.

doi:10.1016/j.cpc.2007.02.094

Cited by 5 publications

(5 citation statements)

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“…The T 1 ← S 0 vibronic features in 4PN have a distinctive rotational contour ,, consisting of two relatively sharp peaks separated by about 5 cm –1 (a “doublet”) and a broader hump just to the blue of the doublet. As seen in Figures and , the global maximum for a given vibronic band occurs within the lower-frequency member of the doublet.…”

Section: Resultsmentioning

confidence: 99%

“…The higher-frequency member of the doublet represents Δ N = +1 (R-form) bandheads of the overlapping Δ K = 0 sub-bands. The broad hump farther to the blue contains overlapping Δ N = +2 (S-form) branches. , …”

Section: Resultsmentioning

confidence: 99%

“…The broad hump farther to the blue contains overlapping ΔN = +2 (S-form) branches. 2,20 The S 1 ← S 0 features in the CRD spectrum (Figure 2) are much broader than the T 1 ← S 0 vibronic bands. The greater widths in the S 1 ← S 0 region are likely due to the presence of closely spaced, unresolved satellite bands associated with the ring-bending mode, ν 18 .…”

Section: ■ Introductionmentioning

confidence: 99%

“…In the S 1 (n,π*) ← S 0 band system, vibronic coupling to 1 (π,π*) states, under the C 2v point group, allows N i f transitions in which N has a 2 or b 1 symmetry and i and f are of different parity. 3 The T 1 ← S 0 vibronic features in 4PN have a distinctive rotational contour 2,19,20 consisting of two relatively sharp peaks separated by about 5 cm −1 (a "doublet") and a broader hump . CRD spectrum of 4PN vapor at room temperature, including vibronic assignments within the T 1 (n,π*) ← S 0 or S 1 (n,π*) ← S 0 band system.…”

Section: ■ Introductionmentioning

confidence: 99%

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Triplet and Singlet (n,π*) Excited States of 4H-Pyran-4-one Characterized by Cavity Ringdown Spectroscopy and Quantum-Chemical Calculations

et al. 2019

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The 4H-pyran-4-one (4PN) molecule serves as a model for investigating structural changes following π* ← n electronic excitation. We have recorded the cavity ringdown (CRD) absorption spectrum of 4PN vapor at room temperature, over the wavelength region from 350 to 370 nm. This spectral region includes the T1(n,π*) ← S0 band system as well as the low-energy portion of the S1(n,π*) ← S0 system. Aided by predictions from ab initio (equation-of-motion excitation energies with dynamical correlation incorporated at the level of coupled cluster singles doubles, EOM-EE-CCSD) and density functional theory (time-dependent density functional theory with PBE0 functional, TDPBE0) calculations, we have made vibronic assignments for about 30 features in the CRD spectrum, mostly T1(n,π*) ← S0 transitions. We have used these results to correct certain vibronic assignments appearing in the previous literature for both T1(n,π*) ← S0 and S1(n,π*) ← S0 band systems. We conclude that the lowest-energy carbonyl wagging fundamentals (ν27, in-plane and ν17, out-of-plane) undergo significant frequency drops (28 and 50%, respectively) upon T1(n,π*) ← S0 excitation and similar drops (29 and 39%, respectively) for S1(n,π*) ← S0 excitation. We find that vibrational modes involving the conjugated ring atoms undergo relatively small frequency changes upon π* ← n excitation, for both T1 and S1 states. We have used the present spectroscopic results and vibronic assignments to test the accuracy of computed excited-state frequencies for 4PN. This benchmarking process shows that the economical time-dependent density functional theory method is impressively accurate for certain (but not all) vibrational modes. The highly correlated EOM-EE-CCSD ab initio method is capable of making accurate frequency predictions, but the results, unexpectedly, depend sensitively on basis set family. This anomaly is traceable to a computed conical intersection between the T1(n,π*) and T2(π,π*) surfaces near the T1(n,π*) potential minimum. Relatively small errors in the location of the conical intersection lead to enhanced mixing of the two electronic states and incorrect T1(n,π*) vibrational frequencies when certain triple-ζ quality basis sets are used.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Triplet and Singlet (n,π*) Excited States of 4H-Pyran-4-one Characterized by Cavity Ringdown Spectroscopy and Quantum-Chemical Calculations

et al. 2019

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“…21 transitions. 22 Judge recently modified 23 the original program, suitable for molecules of orthorhombic symmetry, so that it applies to molecules with C s symmetry, such as acrolein.…”

Section: Introductionmentioning

confidence: 99%

Lowest triplet (n, π*) electronic state of acrolein: Determination of structural parameters by cavity ringdown spectroscopy and quantum-chemical methods

Hlavacek

McAnally

Drucker

2013

The Journal of Chemical Physics

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The cavity ringdown absorption spectrum of acrolein (propenal, CH(2)=CH-CH=O) was recorded near 412 nm, under bulk-gas conditions at room temperature and in a free-jet expansion. The measured spectral region includes the 0(0)(0) band of the T(1)(n, π*) ← S(0) system. We analyzed the 0(0)(0) rotational contour by using the STROTA computer program [R. H. Judge et al., J. Chem. Phys. 103, 5343 (1995)], which incorporates an asymmetric rotor Hamiltonian for simulating and fitting singlet-triplet spectra. We used the program to fit T(1)(n, π*) inertial constants to the room-temperature contour. The determined values (cm(-1)), with 2σ confidence intervals, are A = 1.662 ± 0.003, B = 0.1485 ± 0.0006, C = 0.1363 ± 0.0004. Linewidth analysis of the jet-cooled spectrum yielded a value of 14 ± 2 ps for the lifetime of isolated acrolein molecules in the T(1)(n, π*), v = 0 state. We discuss the observed lifetime in the context of previous computational work on acrolein photochemistry. The spectroscopically derived inertial constants for the T(1)(n, π*) state were used to benchmark a variety of computational methods. One focus was on complete active space methods, such as complete active space self-consistent field (CASSCF) and second-order perturbation theory with a CASSCF reference function (CASPT2), which are applicable to excited states. We also examined the equation-of-motion coupled-cluster and time-dependent density function theory excited-state methods, and finally unrestricted ground-state techniques, including unrestricted density functional theory and unrestricted coupled-cluster theory with single and double and perturbative triple excitations. For each of the above methods, we or others [O. S. Bokareva et al., Int. J. Quantum Chem. 108, 2719 (2008)] used a triple zeta-quality basis set to optimize the T(1)(n, π*) geometry of acrolein. We find that the multiconfigurational methods provide the best agreement with fitted inertial constants, while the economical unrestricted Perdew-Burke-Ernzerhof exchange-correlation hybrid functional (UPBE0) technique performs nearly as well.

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Predissociation and spectroscopy of the 3A2(000) state of 18O3 from CRDS spectra of the 3A2(000)←X1A1(110) hot band near 7900cm−1

Mondelain

Jost

Kassi

et al. 2012

Journal of Quantitative Spectroscopy and Radiative Transfer

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A new graphical version of STROTAB: The analysis and fitting of singlet–triplet spectra of asymmetric top molecules in the prolate or oblate limits

Cited by 5 publications

References 7 publications

Triplet and Singlet (n,π*) Excited States of 4H-Pyran-4-one Characterized by Cavity Ringdown Spectroscopy and Quantum-Chemical Calculations

Triplet and Singlet (n,π*) Excited States of 4H-Pyran-4-one Characterized by Cavity Ringdown Spectroscopy and Quantum-Chemical Calculations

Lowest triplet (n, π*) electronic state of acrolein: Determination of structural parameters by cavity ringdown spectroscopy and quantum-chemical methods

Predissociation and spectroscopy of the 3A2(000) state of 18O3 from CRDS spectra of the 3A2(000)←X1A1(110) hot band near 7900cm−1

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