Photochemistry of benzene isomers. 1. Fulvene and 3,4-dimethylenecyclobutene

We consider photoinduced electronic transitions through conical intersections in large molecules.Starting from the linear vibronic model Hamiltonian and treating linear diabatic couplings within the second order cumulant expansion we have developed a simple analytical expression for the time evolution of electronic populations at finite temperature. The derived expression can be seen as a nonequilibrium generalization of the Fermi Golden Rule due to a nonequilibrium character of the initial photoinduced nuclear distribution. All parameters in our model are obtained from electronic structure calculations followed by a diabatization procedure. The results of our model are found to agree well with those of quantum dynamics for a test set of systems: fulvene molecule, bis-methylene adamantane cation and its dimethyl derivative.

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Section: A Fulvenementioning

confidence: 99%

“…36 Moreover, deactivation of the S 1 state proceeds without any fluorescence. 36 These experimental observations were explained by finding areas of interstate crossings between S 0 and S 1 states. 37 According to C 2v symmetry, at the FC point, S 0 and S 1 states have A 1 and B 2 symmetries, respectively.…”

Section: A Fulvenementioning

confidence: 99%

Nonequilibrium Fermi golden rule for electronic transitions through conical intersections

Izmaylov

Mendive-Tapia²,

Bearpark³

et al. 2011

The Journal of Chemical Physics

108

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“…The photophysics of fulvene is characterized by a broad, weak, and diffuse S 1 absorption band, corresponding to a valence excited state of B 2 symmetry. [21][22][23] The shape of the band is thought to arise from large geometry changes that occur immediately after the excitation, and the absence of fluorescence suggests the presence of a conical intersection seam between the ground and lowest excited state that enables the fast decay of the excited species. These experimental features have been explained by ab initio calculations that show that there is an energetically accessible S 1 /S 0 seam of conical intersection.…”

Section: Introductionmentioning

confidence: 99%

Quantum dynamics study of fulvene double bond photoisomerization: The role of intramolecular vibrational energy redistribution and excitation energy

Blancafort

Gatti

Meyer

2011

The Journal of Chemical Physics

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The double bond photoisomerization of fulvene has been studied with quantum dynamics calculations using the multi-configuration time-dependent Hartree method. Fulvene is a test case to develop optical control strategies based on the knowledge of the excited state decay mechanism. The decay takes place on a time scale of several hundred femtoseconds, and the potential energy surface is centered around a conical intersection seam between the ground and excited state. The competition between unreactive decay and photoisomerization depends on the region of the seam accessed during the decay. The dynamics are carried out on a four-dimensional model surface, parametrized from complete active space self-consistent field calculations, that captures the main features of the seam (energy and locus of the seam and associated branching space vectors). Wave packet propagations initiated by single laser pulses of 5-25 fs duration and 1.85-4 eV excitation energy show the principal characteristics of the first 150 fs of the photodynamics. Initially, the excitation energy is transferred to a bond stretching mode that leads the wave packet to the seam, inducing the regeneration of the reactant. The photoisomerization starts after the vibrational energy has flowed from the bond stretching to the torsional mode. In our propagations, intramolecular energy redistribution (IVR) is accelerated for higher excess energies along the bond stretch mode. Thus, the competition between unreactive decay and isomerization depends on the rate of IVR between the bond stretch and torsion coordinates, which in turn depends on the excitation energy. These results set the ground for the development of future optical control strategies.

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“…The kinetics of this reaction from the optically accessible singlet states has been investigated. 5 On the other hand, nothing is known about the triplet states of fulvene and its derivatives. This is unfortunate because an interesting behavior of fulvene in its lowest triplet state has been predicted by means of molecular orbital theory.…”

Section: Introductionmentioning

confidence: 99%

Electron-energy-loss spectroscopy of 6,6′-dimethylfulvene: First detection of the triplet state

Swiderek

Michaud

Sanche

1995

The Journal of Chemical Physics

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Photochemistry of benzene isomers. 1. Fulvene and 3,4-dimethylenecyclobutene

Cited by 34 publications

References 7 publications

Nonequilibrium Fermi golden rule for electronic transitions through conical intersections

Nonequilibrium Fermi golden rule for electronic transitions through conical intersections

Quantum dynamics study of fulvene double bond photoisomerization: The role of intramolecular vibrational energy redistribution and excitation energy

Electron-energy-loss spectroscopy of 6,6′-dimethylfulvene: First detection of the triplet state

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