Temperature dependence of fluorescence quantum yield, decay time and intersystem crossing activation energy of 9-acetoxy-10-acetoxyhalogenphenylanthracene derivatives

1986 ◽  
Vol 142 ◽  
pp. 183-188 ◽  
Author(s):  
J.R. Heldt ◽  
H. Diehl
Keyword(s):  
Activation Energy ◽  
Quantum Yield ◽  
Temperature Dependence ◽  
Decay Time ◽  
Fluorescence Quantum Yield ◽  
Intersystem Crossing

Effects of Pressure and Temperature on the Fluorescence Quantum Yield of N-Methylacridone in Solution Interpreted in Terms of the Eyring Transition-StateTheory

1981 ◽  
Vol 36 (5) ◽  
pp. 489-493
Author(s):  
H.-D. Brauer ◽  
R. Schmidt ◽  
B. Hammerich
Keyword(s):  
Quantum Yield ◽  
Fluorescence Quantum Yield ◽  
Energy Gap ◽  
State Theory ◽  
Intersystem Crossing ◽  
Thermally Activated ◽  
Elevated Pressures ◽  
Condon Factors ◽  
Positive Volume ◽  
Franck Condon

Abstract The influence of temperatur and pressure on the fluorescence quantum yield of N-methylacridone (9,10-dihydro-9-oxo-10-methyl-acridine) in toluene in the range of 283-313 K and 1 bar to 2.5 kbar, respectively, has been investigated. Treatment of the data in terms of the Eyring transition-state theory leads to a consistent interpretation of the observed effect. The unusually large increase of the quantum yield with increasing pressure is attributed to a positive volume of activation, ⊿V≠, for the thermally activated S1-T2 intersystem crossing which is known to be the only deactivation process (of the Si-state) competing with fluorescence. Comparison of the values for ⊿H≠, the activation enthalpy of this process, determined at various pressures, indicates a decrease in ⊿H≠ at elevated pressures. Since ⊿H≠ can be associated with the S1-T2 energy gap involved in intersystem crossing, this result further confirms the conclusion that the change in Franck-Condon factors alone cannot account for the decrease in the intersystem crossing rate with increasing pressure.

Die Abklingdauer der Fluoreszenz von Naphthalin-Kristallen

1967 ◽  
Vol 22 (8) ◽  
pp. 1242-1246 ◽  
Author(s):  
T. B. El-Kareh ◽  
H. C. Wolf
Keyword(s):  
Simple Model ◽  
Quantum Yield ◽  
Temperature Dependence ◽  
Electronic State ◽  
Oscillator Strength ◽  
Short Duration ◽  
Decay Time ◽  
Fluorescence Decay ◽  
Sample Thickness ◽  
Fluorescence Decay Time

The fluorescence decay time of naphthalene crystals has been measured as a function of sample thickness (1 μ-1 cm) and temperature (4.2°K-300°K) when excited in the first electronic state with UV pulses of short duration. A simple model is proposed to explain the decay mechanism, assuming constant quantum yield and oscillator strength and taking into account both Davydov-levels A and B. The reabsorption is found to be directly proportional to the temperature. The decay time of the lower Davydov-component can be measured directly as τA = (115 ± 5) nsec. The decay time of the higher level B is calculated from the dependence on the thickness as τB = (20 ± 10) nsec, and from the temperature dependence as TB= (30 ± 10) nsec.

TEMPERATURE DEPENDENCE OF THE FLUORESCENCE QUANTUM YIELD OF PHYTOCHROME

1975 ◽  
Vol 22 (1-2) ◽  
pp. 75-76 ◽  
Author(s):  
Pill-Soon Song ◽  
Quae Chae ◽  
Winslow R. Briggs
Keyword(s):  
Quantum Yield ◽  
Temperature Dependence ◽  
Fluorescence Quantum Yield

Die Temperaturabhangigkeit der Fluoreszenzquantenausbeuten von Donator-Akzeptor-substituierten trans-Stilbenen in Losungsmitteln unterschiedlidier Polaritat

1981 ◽  
Vol 36 (6) ◽  
pp. 626-629
Author(s):  
D. Gloyna ◽  
I. Gryczyński ◽  
A. Kawski
Keyword(s):  
Quantum Yield ◽  
Temperature Dependence ◽  
Rate Constant ◽  
Fluorescence Quantum Yield ◽  
Activation Energies ◽  
Solvent Interaction ◽  
Temperature Range ◽  
Hammett Constants ◽  
Donor Acceptor ◽  
Solute Solvent Interaction

Abstract The temperature dependence of the fluorescence quantum yield of donor-acceptor-substituted trans-stilbenes (1) in n-heptane, toluene and dimethylformamide (DMF) in the temperature range of 5-70 °C is due to twisting of the excited Si state to the perp.-S1 state. Twisting and fluorescence are the predominant deactivation processes. Within the series of 4'-acceptor-substituted substances 1g, 1b, 1h- 1k, the activation energies, Etp, in n-heptane and DMF are correlated with the Hammett constants atp of the acceptor in a way comparable to the correlaton between the twisting rate constant kt„ and Aσp. No such correlation was found with toluene. The deactivation of the S1 state results from two oppositely acting factors: the intramolecular donoracceptor interaction and the intermolecular solute-solvent interaction

Why vertically π-expanded imidazo[1,2-a]pyridines are weak fluorescence emitters: experimental and computational studies

2015 ◽  
Vol 17 (14) ◽  
pp. 8945-8950 ◽  
Author(s):  
Marzena Banasiewicz ◽  
Irena Deperasińska ◽  
Artur Makarewicz ◽  
Dikhi Firmansyah ◽  
Daniel T. Gryko ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Fluorescence Quantum Yield ◽  
Intersystem Crossing ◽  
Computational Studies ◽  
Dft Methods

Two novel π-expanded analogs of imidazo[1,2-a]pyridine are studied by spectroscopic, kinetic and DFT methods. Low fluorescence quantum yield has been attributed to intersystem crossing.

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