scholarly journals Ultrafast intersystem crossing dynamics in uracil unravelled byab initiomolecular dynamics

2014 ◽  
Vol 16 (44) ◽  
pp. 24423-24436 ◽  
Author(s):  
Martin Richter ◽  
Sebastian Mai ◽  
Philipp Marquetand ◽  
Leticia González
Keyword(s):  
Uv Light ◽  
Intersystem Crossing ◽  
Triplet States ◽  
Surface Hopping

Surface hopping simulations of the RNA nucleobase uracil show that intersystem crossing and hence triplet states play an important role during the photorelaxation after excitation with UV light.

scholarly journals Intersystem crossing rates of single perylene molecules in ortho-dichlorobenzene

2016 ◽  
Vol 18 (26) ◽  
pp. 17655-17659 ◽  
Author(s):  
Nico R. Verhart ◽  
Pedro Navarro ◽  
Sanli Faez ◽  
Michel Orrit
Keyword(s):  
Optical Switching ◽  
Intersystem Crossing ◽  
Triplet States ◽  
Spin States ◽  
Molecular Fluorescence

Triplet states can be interesting for optical switching of molecular fluorescence as well as quantum experiments relying on the manipulation of spin states.

Optische Spin-Polarisation im Triplett-Zustand von Naphthalin

1969 ◽  
Vol 24 (6) ◽  
pp. 952-967 ◽  
Author(s):  
M. Schwöhrer ◽  
H. Slxl
Keyword(s):  
Triplet State ◽  
Spin Polarization ◽  
Rate Constants ◽  
Uv Light ◽  
Lattice Relaxation ◽  
Stimulated Emission ◽  
Spin Lattice Relaxation ◽  
Spin Component ◽  
Triplet States ◽  
Selection Rules

Naphthalene, which is excited into the lowest triplet state by unpolarized UV-Iight shows a strong deviation from the Boltzman distribution within the three magnetic sublevels, which is ob­served by ESR. We call this deviation optical spin polarization. In the mixed crystal C10D8: 0.2% C10H8 , where the undeuterated Naphthalene acts as trap at 4.2 °K, the optical spin polarization exceeds the thermal spin polarization such that a steady state inversion between two of the mag­netic sublevels appears. This results in an emissive ESR-transition (stimulated emission of micro- waves). The time dependence of the spin polarization after switching on or off the UV-light is described by a superposition of two exponential functions with different rate constants. - The optical spin polarization is due to spin selection rules for the intersystem crossing process (ISC). These involve primarily the molecular symmetry. - The experimental results of the present paper are these selection rules for the pumping processes: The metastable triplet state is populated via the spin component τx.The depopulation rate constants of the three spin components τx, τv and τz are kx = 0.65 sec-1, ky=0.4 sec-1 and kz=O.15 sec-1 .The spin lattice relaxation probabilities are of the order of 1 sec-1. The latter are dependent on the direction of the magnetic field and on the concentration of the populated triplet states. - These results are compared with a theory of ISC.

Intersystem crossing to higher triplet states in isolated molecules

1973 ◽  
Vol 22 (1) ◽  
pp. 150-153 ◽  
Author(s):  
U. Laor ◽  
J.C. Hsieh ◽  
P.K. Ludwig
Keyword(s):  
Intersystem Crossing ◽  
Triplet States ◽  
Isolated Molecules

Trifluoromethylphenylcarbenes. Carbene-Carbene Interconversion on the Singlet Energy Surface and Rearrangement to Trifluorobenzocyclobutene, Trifluorostyrene, and Trifluoromethylfulvenallenes

2015 ◽  
Vol 68 (1) ◽  
pp. 36 ◽  
Author(s):  
Rodney J. Blanch ◽  
Curt Wentrup
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Esr Spectroscopy ◽  
Energy Surface ◽  
Esr Spectra ◽  
Intersystem Crossing ◽  
Triplet States ◽  
Long Wavelength ◽  
Spin Resonance ◽  
Triplet Carbenes

The four isomeric α-, ortho-, meta-, and para-trifluoromethylphenylcarbenes were generated by photolysis of the corresponding 3-phenyl-3-trifluoromethyldiazirene 1 or the four isomeric trifluoromethylphenyldiazomethanes 2 and 4–6. The four corresponding triplet trifluoromethylphenylcarbenes 3 and 7–9 were observed by electron spin resonance (ESR) spectroscopy in Ar matrices at 14 K. The α- and ortho-carbenes 3 and 7 and the ortho- and para-carbenes 7 and 9 interconvert partially when generated by short-wavelength photolysis (350 nm) before intersystem crossing to the triplet states. The triplet states do not undergo further Carbene-Carbene interconversion. The interconversions are assumed to take place via the meta-trifluoromethylphenylcarbene 8. When the ortho- and para-carbenes are generated by long-wavelength photolysis (>450 nm), the discrete, non-interconverting triplet carbenes are observed in the ESR spectra. Flash vacuum thermolysis of the diazirene 1 at 500°C afforded a mixture of bis(trifluoromethyl)heptafulvalenes 11, bis(trifluoromethyl)stilbenes 12, and bis(trifluoromethyl)anthracenes 13, and the presence of their likely precursor(s), trifluoromethylcycloheptatetraene(s), was confirmed by a peak at 1830 cm–1 in the Ar matrix IR spectrum. In addition, at 700°C, four monomeric carbene rearrangement products were isolated and characterised, viz. 1,1,2-trifluorobenzocyclobutene 14, 1′,2′,2′-trifluorostyrene 15, and 1- and 2-trifluoromethylfulvenallenes 16 and 17.

scholarly journals The role of Duschinsky rotation in intersystem crossing: A case study of uracil

2011 ◽  
Vol 76 (12) ◽  
pp. 1649-1660 ◽  
Author(s):  
Mihajlo Etinski
Keyword(s):  
Correlation Function ◽  
Normal Modes ◽  
Intersystem Crossing ◽  
Triplet States ◽  
Cumulant Expansion ◽  
Time Approximation ◽  
Energy Gaps ◽  
Singlet And Triplet States ◽  
Quantitative Results ◽  
Short Time

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.

scholarly journals Highly efficient surface hopping dynamics using a linear vibronic coupling model

2019 ◽  
Vol 21 (1) ◽  
pp. 57-69 ◽  
Author(s):  
Felix Plasser ◽  
Sandra Gómez ◽  
Maximilian F. S. J. Menger ◽  
Sebastian Mai ◽  
Leticia González
Keyword(s):  
Internal Conversion ◽  
Coupling Model ◽  
Vibronic Coupling ◽  
Intersystem Crossing ◽  
Nonadiabatic Dynamics ◽  
Surface Hopping ◽  
Highly Efficient ◽  
Dynamics Simulations

A highly efficient protocol for performing nonadiabatic dynamics simulations is implemented and applied to ultrafast internal conversion and intersystem crossing in various molecules.

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