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Ultrafast deactivation mechanism of the excited singlet in the light-induced spin crossover of [Fe(2,2'-bipyridine)3]2+.
This work investigates how the initially excited metal-to-ligand charge transfer (MLCT) singlet state deactivates to the final metastable high-spin state and determines all the intermediate electronic states along the pathway from low spin to high spin and gives estimates for the deactivation times of the different stages. Expand
Intersystem crossing and characterization of dark states in the pyrimidine nucleobases uracil, thymine, and 1-methylthymine.
The results clearly indicate that the S(2)((1)pi-->pi*)-->T( 2)((3)n -->pi*) process cannot compete with the subpicosecond decay of the S (2) population due to spin-allowed nonradiative transitions, whereas the T(1)(( 3)pi)--pi*) state is populated from the intermediate S(1)* state on a subnanosecond time scale. Expand
Time-dependent approaches for the calculation of intersystem crossing rates.
The comparison suggests that the cumulant expansion approximates the exact expression very well while allowing the interval of the time integration to be significantly shorter, and in cases with sufficiently high vibrational density of states also the short-time approximation yields rates in good agreement with the results of the exact formula. Expand
Overruling the energy gap law: fast triplet formation in 6-azauracil.
  • M. Etinski, C. Marian
  • Chemistry, Medicine
  • Physical chemistry chemical physics : PCCP
  • 29 November 2010
The photophysical properties of 6-azauracil were studied by means of ab initio quantum chemical methods and the following mechanism for the lack of fluorescence and the high triplet quantum yield that was observed experimentally after irradiation of this compound with UV light is proposed. Expand
Comparison between time-dependent and time-independent methods for the calculation of inter-system crossing rates: Application to uracil and its derivatives
Der erste Teil dieser Arbeit beschaftigt sich mit der theoretischen Formulierung des Problems, Interkombinationsraten in Molekulen effizient zu evaluieren. Dafur werden zeitunabhangige- undExpand
A Theoretical Investigation of the Geometries and Binding Energies of Molecular Tweezer and Clip Host-Guest Systems.
The good results obtained with the DFT-D-BLYP method suggest this approach as a standard tool in supramolecular chemistry and as the method of choice for theoretical structure determinations of large complexes where both electrostatic and dispersion interactions are crucial. Expand
Ab initio investigation of the methylation and hydration effects on the electronic spectra of uracil and thymine.
The lowest-lying singlet and triplet n-->pi* states are insensitive to methylation but are strongly blue-shifted by microhydration and bulk water solvation and shifting them energetically above the primarily excited (1)(pi-->pi*) state will considerably decrease the triplet quantum yield and thus increase the photostability of the compounds. Expand
Time-dependent approach to spin-vibronic coupling: implementation and assessment.
The generalization of a time-dependent method for the calculation of intersystem crossing (ISC) rates in the Condon approximation is presented, based on the generating function formalism and the multi-mode harmonic oscillator approximation. Expand
Intersystem crossing rates of S1 state keto-amino cytosine at low excess energy.
The amino-keto tautomer of supersonic jet-cooled cytosine undergoes intersystem crossing (ISC) from the v = 0 and low-lying vibronic levels of its S1((1)ππ(∗)) state. We investigate these ISC ratesExpand
Electronic and vibrational spectroscopy of 1-methylthymine and its water clusters: the dark state survives hydration.
Ab initio theory shows that solvation of 1MT by water does not lead to a substantial modification of the electronic relaxation and quenching of the (1)n pi* state, and Oxygen coexpansions and crossed-beam experiments indicate that the triplet state population is probably small compared to the ( 1)npi* and/or hot electronic ground state population. Expand