The  &amp;.sbnd;  (3500 Å) transition of azulene: Medium-dependent effects attributable to vibronic coupling and vibronic Fermi resonance

Lacey, A. R.; McCoy, EF; Ross, I. G.

doi:10.1016/0009-2614(73)80126-5

Cited by 68 publications

(6 citation statements)

References 13 publications

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“…This difficulty can be explained if structures that are attributed to the vibronic rather than we assume that there is a strong vibronic coupling between Franck-Condon activity of the totally symmetric modes. [4][5][6] the So and S 1 states via the b 2 C-C stretching mode leading The latter was confirmed by semi-empirical calculations. 7 to bond alternation.…”

Section: Introductionmentioning

confidence: 69%

On the vibronic structure of the S↔S1 transitions in azulene

Negri

Zgierski

1993

The Journal of Chemical Physics

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Articles you may be interested in S 0↔S 1 transition of transβmethyl styrene: Vibronic structure and dynamicsThe vibronic structure of the S 0↔S 1 and S 0↔S 2 transitions in simple oligomers of thiopheneThe semiempirical (quantum chemical consistent force fieldhr-electron and complete neglect of differential overlap/spectroscopic parametrization) and ab initio methods are used to study the vibronic structure of the optical transitions between the So and SI states of azulene. It is shown that although the excited state is described quite well as arising from the promotion of one electron from the highest occupied molecular orbital to the lowest unoccupied one, the inclusion of doubly excited configurations in description of the wave functions of the two states in question is essential for a proper characterization of the geometry change upon electronic excitation and, therefore, for the resulting Franck-Condon structure of the absorption and emission spectra. The vibronically induced intensities of the b 2 fundamentals in the two spectra are calculated and compared with the experimental data, and the problem of correlation between the b 2 modes in the two states is solved.4318

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Section: Introductionmentioning

confidence: 69%

On the vibronic structure of the S↔S1 transitions in azulene

Negri

Zgierski

1993

The Journal of Chemical Physics

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“…This is due almost exclusively to changes in the energies of the S 1 states because the S 2 states have energies which are only weak functions of the nature and positions of the substituents, at least for the compounds examined here. The reasons for these trends are related to the quantum mechanical descriptions of the S 1 and S 2 states in azulene and other nonalternant aromatic molecules. − The S 1 −S 0 transition in azulene is usefully described as an electric−dipole allowed HOMO−LUMO one-electron transition which has a low oscillator strength because HOMO and LUMO have large amplitudes on different atoms and their overlap is small. Its transition dipole is perpendicular to the long axis of the azulene ring system.…”

Section: Resultsmentioning

confidence: 99%

Control of the Photophysical Properties of Polyatomic Molecules by Substitution and Solvation: The Second Excited Singlet State of Azulene

et al. 1999

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The UV−visible−near-IR absorption spectra, S2 → S0 fluorescence quantum yields and S2 fluorescence lifetimes of 1-fluoroazulene, 1,3-difluoroazulene, and several of their alkyl-substituted derivatives have been measured at room temperature in up to six solvents, benzene, dichloromethane, ethanol, acetonitrile, n-hexane, and perfluoro-n-hexane. The quantum yields (up to 0.2) and lifetimes (up to 9.5 ns) of the S2 state of 1,3-difluoroazulene are exceptionally largethe largest ever reported for an upper excited singlet state of a polyatomic molecule with a closed-shell ground state. The nonradiative rate constants for the decay of the S2 states of these molecules in these solvents and of azulene, 1,3-dichloroazulene and 1,3-dibromoazulene, determined previously, have been analyzed in terms of the weak coupling case of radiationless transition theory. The data show that the nonradiative rate constants for the S2 states of azulene, 1-fluoroazulene, and 1,3-difluoroazulene in the nonpolar solvents follow the log−linear relationship expected of the energy gap law, provided that S2−S1 internal conversion is assumed to dominate the decay mechanism. The same linear correlation is obtained, irrespective of whether ΔE(S2−S1) is varied by solvatochromism or fluorine substitution. Substitution by alkyl groups increases the nonradiative decay rates by increasing the effective number of coupled states while the electronic coupling matrix element remains constant. Substitution at the 6-position by an isopropyl group increases the rate constant by a constant factor of 2.9; however, multiple substitution does not have a multiplicative effect. Substitution by chlorine or bromine increases the S2 decay rates by enhancing the rate of intersystem crossing to the triplet manifold. The rate enhancement is semiquantitatively modeled by considering the effects of spin−orbit coupling of the halogen atoms.

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“…For the sake of clarity, let us first review the most important results on the S 0 → S n spectrum of azulene − which are pertinent to our study, making reference to Figure for the axis reference system and to Figure for the ground-state absorption spectrum. There are four distinct absorption regions in the azulene spectrum: ≈700−500 nm, 350−310 nm, 290−260 nm, 240−220 nm, with oscillator strengths 0.009, 0.06, ≈1, and 0.4, respectively .…”

Section: Excited State Absorption Of Azulenementioning

confidence: 99%

S₁ → S_n and S₂ → S_n Absorption of Azulene: Femtosecond Transient Spectra and Excited State Calculations

et al. 2003

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The transient spectra of azulene in solution have been measured in the spectral region 600−350 nm at room temperature, pumping into the S1 and S2 states with femtosecond pulses and probing with a delayed femtosecond white light continumm. The spectra are a combination of ground-state bleaching, stimulated emission, and excited-state absorption. The latter component gives a direct information on excited states which may be not active in the ground-state absorption. S1 → S n and S2 → S n absorptions have been discussed with the help of ab initio calculations of the MCSCF/CAS type with the 6-31G* basis set and including perturbative corrections. The calculated S0 → S n , S1, eq → S n , and S2, eq → S n vertical excitation energies and oscillator strengths are in satisfactory agreement with the experimental results. It has been found that electronic states, weakly active in the ground-state absorption, occur with high intensity in the femtosecond transient spectra, in particular in the energy range 36000−44000 cm-1 above the ground-state energy.

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The &.sbnd; (3500 Å) transition of azulene: Medium-dependent effects attributable to vibronic coupling and vibronic Fermi resonance

Cited by 68 publications

References 13 publications

On the vibronic structure of the S↔S1 transitions in azulene

On the vibronic structure of the S↔S1 transitions in azulene

Control of the Photophysical Properties of Polyatomic Molecules by Substitution and Solvation: The Second Excited Singlet State of Azulene

S₁ → S_n and S₂ → S_n Absorption of Azulene: Femtosecond Transient Spectra and Excited State Calculations

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The &.sbnd; (3500 Å) transition of azulene: Medium-dependent effects attributable to vibronic coupling and vibronic Fermi resonance

Cited by 68 publications

References 13 publications

On the vibronic structure of the S↔S1 transitions in azulene

On the vibronic structure of the S↔S1 transitions in azulene

Control of the Photophysical Properties of Polyatomic Molecules by Substitution and Solvation: The Second Excited Singlet State of Azulene

S1 → Sn and S2 → Sn Absorption of Azulene: Femtosecond Transient Spectra and Excited State Calculations

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S₁ → S_n and S₂ → S_n Absorption of Azulene: Femtosecond Transient Spectra and Excited State Calculations