Viscosity Dependence of the First‐Order Decay of the Triplet State of Anthracene and Related Molecules

1963 ◽  
Vol 39 (10) ◽  
pp. 2593-2598 ◽  
Author(s):  
Robert Livingston ◽  
William R. Ware
Keyword(s):  
Triplet State ◽  
First Order ◽  
Viscosity Dependence

scholarly journals Quenching of hexafluoroacetone phosphorescence by mercury

1968 ◽  
Vol 46 (6) ◽  
pp. 1031-1033 ◽  
Author(s):  
N. C. Lang ◽  
K. O. Kutschke
Keyword(s):  
Triplet State ◽  
Linear Function ◽  
Excellent Agreement ◽  
Mercury Concentration ◽  
Relative Yield ◽  
Lifetime Measurements ◽  
First Order

The ratio of the relative yield for fluorescence to that for phosphorescence of hexafluoroacetone excited at 3130 Å was measured; the ratio was a linear function of mercury concentration. This observation confirms that the deactivation of the triplet state proceeds by a reaction which is first order in [Hg]. A quenching constant was obtained which is in excellent agreement with that based on lifetime measurements under mercury-free and mercury-saturated conditions.

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.

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

Decay of the triplet state I. First-order processes in solution

1964 ◽  
Vol 277 (1371) ◽  
pp. 437-447 ◽  
Keyword(s):  
Triplet State ◽  
Propylene Glycol ◽  
Low Temperatures ◽  
Flash Photolysis ◽  
High Viscosity ◽  
Experimental Arrangement ◽  
First Order ◽  
Low Viscosity ◽  
Diffusion Controlled ◽  
Glycol Solution

The decay of the trip let states of naphthalene, 2-bromonaphthalene, anthracene, 1,5-dichloroanthracene and 9-bromophenanthrene have been studied in isopentane solution over the temperature range 22 to —196 °C and in propylene glycol solution from 54 to —80 °C, corresponding to a variation in viscosity by a factor of 10 8 . An experimental arrangement for flash photolysis investigations at low temperatures is described. When allowance is made for discontinuities in the viscosity-temperature relations all our measurements are accounted for in terms of two regimes of trip let decay: a high viscosity regime where rate is nearly independent of temperature and viscosity and the mechanism is truly unimolecular and a low viscosity regime w here diffusion-controlled quenching processes are operative.

Radiationless conversion from the triplet state

1962 ◽  
Vol 268 (1332) ◽  
pp. 46-56 ◽  
Keyword(s):  
Triplet State ◽  
Ground State ◽  
Fold Increase ◽  
Solvent Viscosity ◽  
First Order ◽  
Quenching Process ◽  
Anthracene Derivatives ◽  
The One ◽  
Bimolecular Quenching ◽  
Derivatives Of

The first-order decay of trip let states of naphthalene, anthracene, phenanthrene and their halogenated derivatives has been studied in cyclohexane and viscous paraffin solutions. The decay results partly from a bimolecular quenching process and partly from a true first-order radiationless conversion to the ground state. The rate of the quenching process is a function of the solvent, and, in anthracene derivatives, of the extent to which the solutions have been irradiated. The rates of radiationless conversion can only be measured when they exceed the rates of quenching processes. This is the case for all the anthracene derivatives in viscous paraffin, for the bromoanthracenes in cyclohexane and probably for bromophenanthrene in viscous paraffins. Bromination of anthracene is ten times more effective in enhancing conversion than chlorination at the same position and halogenation at the 9, 10 positions has four times the effect of halogenation at other positions. In the one case where it could be tested (dibromoanthracene), the rate of radiationless conversion was unchanged by a 170-fold increase of solvent viscosity.

Dual systems for all: Higher-order, role-based relational reasoning as a uniquely derived feature of human cognition

2019 ◽  
Vol 42 ◽  
Author(s):  
Daniel J. Povinelli ◽  
Gabrielle C. Glorioso ◽  
Shannon L. Kuznar ◽  
Mateja Pavlic
Keyword(s):  
Temporal Reasoning ◽  
Higher Order ◽  
Important Case ◽  
Human Cognition ◽  
Relational Reasoning ◽  
Dual Systems ◽  
First Order ◽  
Reasoning System ◽  
Role Based

Abstract Hoerl and McCormack demonstrate that although animals possess a sophisticated temporal updating system, there is no evidence that they also possess a temporal reasoning system. This important case study is directly related to the broader claim that although animals are manifestly capable of first-order (perceptually-based) relational reasoning, they lack the capacity for higher-order, role-based relational reasoning. We argue this distinction applies to all domains of cognition.

Stochasting modeling of planetary ring systems

1984 ◽  
Vol 75 ◽  
pp. 461-469 ◽  
Author(s):  
Robert W. Hart
Keyword(s):  
Maximum Entropy ◽  
Ring System ◽  
The Sun ◽  
Ultimate State ◽  
Interparticle Interactions ◽  
Ring Systems ◽  
First Order ◽  
Planetary Ring ◽  
Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

Morphological studies of linear (AB)n multiblock copolymers and their blends

1992 ◽  
Vol 50 (1) ◽  
pp. 384-385
Author(s):  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf
Keyword(s):  
Electron Microscopy ◽  
Microphase Separation ◽  
Multiblock Copolymers ◽  
First Order ◽  
Morphological Studies ◽  
Transmission Electron ◽  
First Order Phase Transition ◽  
Covalently Bonded ◽  
Total Molecular Weight ◽  
First Order Phase

Block copolymers are composed of sequences of dissimilar chemical moieties covalently bonded together. If the block lengths of each component are sufficiently long and the blocks are thermodynamically incompatible, these materials are capable of undergoing microphase separation, a weak first-order phase transition which results in the formation of an ordered microstructural network. Most efforts designed to elucidate the phase and configurational behavior in these copolymers have focused on the simple AB and ABA designs. Few studies have thus far targeted the perfectly-alternating multiblock (AB)n architecture. In this work, two series of neat (AB)n copolymers have been synthesized from styrene and isoprene monomers at a composition of 50 wt% polystyrene (PS). In Set I, the total molecular weight is held constant while the number of AB block pairs (n) is increased from one to four (which results in shorter blocks). Set II consists of materials in which the block lengths are held constant and n is varied again from one to four (which results in longer chains). Transmission electron microscopy (TEM) has been employed here to investigate the morphologies and phase behavior of these materials and their blends.

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.

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