Front Cover: Efficient Direct Reverse Intersystem Crossing between Charge Transfer‐Type Singlet and Triplet States in a Purely Organic Molecule (7/2021)

The intersystem crossing rate for the transition between the lowest excited singlet and triplet electronic states of uracil was studied by means of ab initio methods. The rate was evaluated using the timedependent approach based on the correlation function and its two approximations: the second-order cumulant expansion and the short-time approximation. The normal modes of the singlet and triplet states are related by the Duschinsky transformation, i.e., by rotation and translation. It was found that for singlet-triplet adiabatic energy gaps below 6000 cm-1, the inclusion of the Duschinsky rotation is necessary for quantitative results. Above energy gaps of 6000 cm-1, the rates obtained with and without the Duschinsky rotation are similar. The cumulant expansion approximates well the correlation function. The short-time approximation, although crude, can be used as the first estimate of the rate.

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The mechanism of the gas phase photolysis of acetone

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1966.0071 ◽

1966 ◽

Vol 290 (1423) ◽

pp. 563-582 ◽

Cited By ~ 44

Keyword(s):

Gas Phase ◽

Order Rate Constant ◽

Electronic Energy ◽

Intersystem Crossing ◽

Triplet States ◽

Excited Singlet ◽

First Order ◽

Electronic Energy Transfer ◽

Vibrational Levels ◽

Singlet And Triplet States

A mechanism for the photolysis of acetone has been derived from experimental data including studies on the photosensitized isomerization of olefines. Dissociation into methyl and acetyl radicals occurs from both the first excited singlet and triplet states; the rate constants for excitation by light of 3130 Å wavelength are 2.5 x 10 16 exp ( —16900/ RT ) and 2.5 x 10 10 exp ( — 6400/ RT ) 1. mole -1 s -1 respectively. At low intensities of absorption, decomposition of acetyl radicals predominates over radical-radical interactions. The triplet state is extensively populated at moderate temperatures, the yield at 48 °C being 0.98. The low phosphorescence efficiency of acetone can be ascribed to intersystem crossing to the ground state for which the first order rate constant is 1.25 x 10 5 s -1 . The isomerization data requires the recognition of at least two vibrational levels of the acetone triplet, the rate of electronic energy transfer depending upon the excess energy possessed by the donor

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Photophysical Properties of Nitrated and Halogenated Phosphorus Tritolylcorrole Complexes: Insights from Theory

Molecules ◽

10.3390/molecules23112779 ◽

2018 ◽

Vol 23 (11) ◽

pp. 2779 ◽

Cited By ~ 4

Author(s):

Marta Alberto ◽

Bruna De Simone ◽

Gloria Mazzone ◽

Nino Russo ◽

Marirosa Toscano

Keyword(s):

Excited States ◽

Density Functional ◽

Energy Gap ◽

Photophysical Properties ◽

Intersystem Crossing ◽

Triplet States ◽

Excited Singlet ◽

Functional Theory ◽

The Density Functional Theory ◽

Singlet And Triplet States

The photophysical properties of a series of nitrated and halogenated phosphorus tritolylcorrole complexes were studied in dichloromethane solvent by using the density functional theory. Particular emphasis was given to the absorption spectra, the energy gap between the excited singlet and triplet states, and the magnitude of the spin-orbit couplings for a series of possible intersystem crossing channels between those excited states. The proposed study provides a better description of the photophysical properties of these systems while giving insights into their possible use as photosensitizers in photodynamic therapy.

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Influence of Chain Length and Derivatization on the Lowest Singlet and Triplet States and Intersystem Crossing in Oligothiophenes

Journal of the American Chemical Society ◽

10.1021/ja9531135 ◽

1996 ◽

Vol 118 (27) ◽

pp. 6453-6461 ◽

Cited By ~ 153

Author(s):

D. Beljonne ◽

J. Cornil ◽

R. H. Friend ◽

R. A. J. Janssen ◽

J. L. Brédas

Keyword(s):

Chain Length ◽

Intersystem Crossing ◽

Triplet States ◽

Singlet And Triplet States

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THEORETICAL STUDY OF HIGHLY DOPED HETEROFULLERENES EVOLVED FROM THE D6h SYMMETRY C36 CAGE

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633613500673 ◽

2013 ◽

Vol 12 (07) ◽

pp. 1350067

Author(s):

F. NADERI ◽

M. R. MOMENI ◽

F. A. SHAKIB

Keyword(s):

Charge Transfer ◽

Hydrogen Storage ◽

Electronic Properties ◽

Vibrational Frequency ◽

Theoretical Study ◽

Binding Energies ◽

Triplet States ◽

Electronic Excitations ◽

Singlet And Triplet States ◽

Homo Lumo

The structural stabilities and electronic properties of singlet and triplet states C 24X12 heterofullerenes where X = B , Al , C , Si , N , and P are probed at the B3LYP/6-31+G* level of theory. Vibrational frequency calculations show that all of the systems are true minima. The calculated binding energies of heterofullerenes show C 24 B 12 and C 24 N 12 as the most stable heterofullerenes by 6.10 eV/atom and 5.63 eV/atom, respectively. While B , Al , N and P doping increase the conductivity of fullerene through decreasing its HOMO–LUMO gap, doping Si enhance its stability against electronic excitations via increasing the HOMO–LUMO gap. High charge transfer on the surfaces of our stable heterofullerenes, especially C 24 Al 12 followed by C 24 Si 12 and C 24 P 12, provokes further investigations on their possible application for hydrogen storage.

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