Viscosity Dependence of Unimolecular Conversion from the Triplet State

Nature ◽  
1962 ◽  
Vol 195 (4845) ◽  
pp. 991-992 ◽  
Author(s):  
G. PORTER ◽  
L. J. STIEF
Keyword(s):  
Triplet State ◽  
Viscosity Dependence

The kinetics of phosphorescence and delayed fluorescence decay for aromatic hydrocarbons in liquid paraffin

1964 ◽  
Vol 281 (1386) ◽  
pp. 420-436 ◽  
Keyword(s):  
Triplet State ◽  
Incident Light ◽  
Liquid Paraffin ◽  
Solute Concentration ◽  
Fluorescence Decay ◽  
Delayed Fluorescence ◽  
Linear Functions ◽  
Temperature Ranges ◽  
Kinetics Of ◽  
Viscosity Dependence

The decay constants k T for phosphorescence and k D for delayed fluorescence have been measured for the same outgassed solutions of acenaphthene, pyrene, 1,2-benzanthracene and fluoranthene in liquid paraffin over a range of temperatures between – 70 and 30 °C. In all cases the luminescence decay is exponential and the intensity of delayed fluorescence is found to vary as the second power of incident light intensity; under these conditions the relation k D = 2 k T required by the triplet-triplet annihilation origin of delayed fluorescence is established over the temperature ranges in which delayed fluorescence and phosphorescence are exhibited simultaneously. Diffusional quenching of the triplet state 3 A by a solute impurity Q is believed to be responsible for the temperature (viscosity) dependence of k T and k D since ( a ) k T and k D are linear functions of solute concentration where this is examined, ( b ) by taking account of the reversibility of the quenching process 3 A + Q ⇌ A + 3 Q at higher temperatures (lower viscosities) the virtual independence of k on temperature exhibited for 1,2-benzanthracene and fluoranthene under these conditions may be explained. The resumed temperature dependence of k D for fluoranthrene at still higher temperatures is attributed to endothermic quenching of the triplet state by an impurity with a higher triplet state than that of the solute.

A nitroreductase-activatable near-infrared theranostic photosensitizer for photodynamic therapy under mild hypoxia

2020 ◽  
Vol 56 (43) ◽  
pp. 5819-5822
Author(s):  
Jing Zheng ◽  
Yongzhuo Liu ◽  
Fengling Song ◽  
Long Jiao ◽  
Yingnan Wu ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Triplet State ◽  
Near Infrared ◽  
Mild Hypoxia

In this study, a near-infrared (NIR) theranostic photosensitizer was developed based on a heptamethine aminocyanine dye with a long-lived triplet state.

Effect of Aggregation on Bacteriochlorin a Triplet-state Formation: A Laser Flash Photolysis Study¶

2002 ◽  
Vol 76 (5) ◽  
pp. 480 ◽  
Author(s):  
Xavier Damoiseau ◽  
Francis Tfibel ◽  
Maryse Hoebeke ◽  
Marie-Pierre Fontaine-Aupart
Keyword(s):  
Triplet State ◽  
State Formation ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash

In the Quest for a Stable Triplet State in Small Polyaromatic Hydrocarbons : An In-Silico Tool for Rational Design and Prediction

2019 ◽  
Author(s):  
Madhumita Rano ◽  
Sumanta K Ghosh ◽  
Debashree Ghosh
Keyword(s):  
Triplet State ◽  
Small Molecules ◽  
In Silico ◽  
Qualitative Agreement ◽  
Rational Design ◽  
Polyaromatic Hydrocarbons ◽  
Spin Hamiltonian ◽  
Spin Frustration ◽  
Computationally Efficient ◽  
High Level

<div>Combining the roles of spin frustration and geometry of odd and even numbered rings in polyaromatic hydrocarbons (PAHs), we design small molecules that show exceedingly small singlet-triplet gaps and stable triplet ground states. Furthermore, a computationally efficient protocol with a model spin Hamiltonian is shown to be capable of qualitative agreement with respect to high level multireference calculations and therefore, can be used for fast molecular discovery and screening.</div>

Stationary fluid convection modes with a Gaussian viscosity dependence of temterature

2016 ◽  
Vol 11 (2) ◽  
pp. 218-225
Author(s):  
V.S. Kuleshov
Keyword(s):  
Computer Code ◽  
Boussinesq Approximation ◽  
Simple Type ◽  
Transfer Coefficients ◽  
Convective Flows ◽  
Heat Transfer Coefficients ◽  
Fluid Convection ◽  
Flat Cell ◽  
Volume Method ◽  
Viscosity Dependence

The results of a numerical modeling of thermo-gravitational convection of abnormally thermo-viscous fluid in a closed square cavity with two vertical adiabatic walls and two horizontal isothermal walls are presented. A model Newtonian liquid for which the dependence of viscosity on temperature is described by a bell function (Gaussian curve) is considered. The natural convection of inhomogeneous liquid is described by the closed mathematical model based on the continuous mechanics equations written in Oberbeck-Boussinesq approximation, where the fluid density is a linear function of temperature. To simulate the fluid flow dynamics, the modified computer code based on the implicit finite volume method and SIMPLE-type algorithm with the second-order temporal accuracy is realized using multiprocessor technology. The effect of the viscosity abnormality on stationary modes of convective flows are studied, the integral heat transfer coefficients in a flat cell are calculated.

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