Triplet state quantum yields for some arom atic hydrocarbons and xanthene dyes in dilute solution

1967 ◽  
Vol 299 (1458) ◽  
pp. 348-353 ◽  
Keyword(s):  
Triplet State ◽  
State Formation ◽  
Heavy Atom ◽  
Quantum Yields ◽  
Triplet States ◽  
Dilute Solution ◽  
Perturbation Techniques ◽  
Excited Singlet ◽  
Xanthene Dyes ◽  
Extinction Coefficients

Quantum yields of triplet state formation and extinction coefficients of the triplet states have been determined by direct depletion methods for solutions of anthracene, phenanthrene, 1,2,5,6-dibenzanthracene, fluorescein, dibromofluorescein, eosin and erythrosin. The values obtained for the hydrocarbons are in reasonable agreement with those obtained by other workers using energy transfer and heavy atom perturbation techniques. In all cases which we have studied, the sum of the quantum yields of fluorescence and triplet state formation is equal to unity within the limits of experimental error, showing that radiationless transfer from the excited singlet to the ground state is negligible.

scholarly journals Phosphoreszenzeigensch aften von Methyl-, Chlor- und Brom-Derivaten des [2.2] Paracyclophans

1987 ◽  
Vol 42 (9) ◽  
pp. 1041-1042 ◽  
Author(s):  
H. Hopf ◽  
E. Hermann
Keyword(s):  
Triplet State ◽  
Fluorescence Spectra ◽  
Heavy Atom ◽  
The Other ◽  
Quantum Yields ◽  
Heavy Atom Effect ◽  
Chloro Derivatives ◽  
Derivatives Of ◽  
Atom Effect

Phosphorescence and fluorescence spectra, quantum yields of phosphorescence and fluorescence as well as phosphorescence lifetimes have been measured of six methyl-, chloro- and bromo-derivatives of [2.2] paracyclophane in ethanol at 77 K. While the chloro-derivatives as well as dibromo-paracyclophane exhibit a normal internal heavy-atom effect behaviour the momobromo-compound shows anomalies. These possibly indicate that in the monobromo-compound an additional pathway of the radiationless deactivation of the lowest triplet state is effective which does not occur with the other compounds.

Electrochemical and photophysical characterization of non-peripherally-octaalkyl substituted dichlorotin(IV) phthalocyanine and tetrabenzotriazaporphyrin compounds

2007 ◽  
Vol 11 (10) ◽  
pp. 761-770 ◽  
Author(s):  
Samson Khene ◽  
Andrew N. Cammidge ◽  
Michael J. Cook ◽  
Tebello Nyokong
Keyword(s):  
Cyclic Voltammetry ◽  
Quantum Yield ◽  
Triplet State ◽  
Electrochemical Behavior ◽  
Heavy Atom ◽  
Quantum Yields ◽  
Redox Processes ◽  
Central Metal ◽  
Atom Effect

Three non-peripherally substituted tin(IV) macrocylic compounds, octahexylphthalocyaninato dichlorotin(IV) (3a), octahexyltetrabenzo-5,10,15- triazaporphyrinato dichlorotin(IV) (3b) and octadecylphthalocyaninato dichlorotin(IV) (3c) were synthesized and their photophysical and electrochemical behavior studied. Complex 3b, containing a CH group in place of one of the aza nitrogen atoms of the phthalocyanine core, shows a split Q-band due to its lower symmetry. The triplet state quantum yields were found to be lower than would be expected on the basis of the heavy atom effect of tin as the central metal for phthalocyanine derivatives (3a and 3c). In contrast, 3b shows a triplet quantum yield Φ T = 0.78. The triplet state lifetimes were solvent dependent, and were higher in tetrahydrofuran than in toluene. Cyclic voltammetry and spectroelectrochemistry of the complexes revealed only ring-based redox processes.

Triplet state formation efficiencies of aromatic hydrocarbons in solution

1968 ◽  
Vol 306 (1485) ◽  
pp. 257-273 ◽  
Keyword(s):  
Triplet State ◽  
State Formation ◽  
Aromatic Hydrocarbons ◽  
Rate Constants ◽  
Internal Conversion ◽  
Transition Probability ◽  
Radiative Transition ◽  
Excited Singlet ◽  
Radiative Transitions ◽  
Solvent Systems

The triplet state formation efficiencies,ф T , of ten aromatic hydrocarbons have been deter­mined in ethanol and, in some cases, in other solvents. Fluorescence yields, ф F , for the various hydrocarbon-solvent systems were measured where literature values were not available. With the exception of coronene the sum of ф F + ф T was found to be unity within experi­mental error, which indicates little or no internal conversion from the first excited singlet state of each hydrocarbon. Rate constants for intersystem crossing, k IS and the ratio k IS / k F , where k F is the radiative transition probability, have been calculated for each hydrocarbon in ethanol. The ratio varies much less than do the separate rate constants and the significance of this is discussed in terms of possible selection rules for spin forbidden non-radiative transitions.

Activation energy barrier for intersystem crossing in platinum phthalocyanine

1976 ◽  
Vol 54 (6) ◽  
pp. 633-637 ◽  
Author(s):  
Tzer-Hsiang Huang ◽  
Klaus E. Rieckhoff ◽  
Eva-Maria Voigt
Keyword(s):  
Triplet State ◽  
Ground State ◽  
Energy Barrier ◽  
Singlet State ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Singlet Ground State ◽  
Activation Energy Barrier ◽  
Excited Singlet ◽  
Platinum Phthalocyanine

Phosphorescence quantum yields and lifetimes of platinum phthalocyanine in α-chloronaphthalene solution are reported for temperatures from 1.3 K to 300 K. Activation energies of intersystem crossing are deduced and found to be Ea = 17 ± 3 cm−1 for crossing from the first excited singlet state to the lowest lying triplet state and Eap = 8 ± 1 cm−1 for crossing from the lowest lying triplet state to the singlet ground state.

scholarly journals Control of triplet state generation in heavy atom-free BODIPY–anthracene dyads by media polarity and structural factors

2018 ◽  
Vol 20 (12) ◽  
pp. 8016-8031 ◽  
Author(s):  
Mikhail A. Filatov ◽  
Safakath Karuthedath ◽  
Pavel M. Polestshuk ◽  
Susan Callaghan ◽  
Keith J. Flanagan ◽  
...  
Keyword(s):  
Excited State ◽  
Triplet State ◽  
State Formation ◽  
Heavy Atom ◽  
Molecular Rotation ◽  
Structural Factors ◽  
Triplet Excited State ◽  
State Generation

Heavy atom-free BODIPY–anthracene dyads show triplet excited state formation via PeT, controlled by molecular rotation and environmental polarity.

scholarly journals Theoretical Analysis of the Effect Provoked by Bromine-Addition on the Thermolysis and Chemiexcitation of a Model Dioxetanone

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Luís Pinto da Silva ◽  
Rui F. J. Pereira ◽  
Joaquim C. G. Esteves da Silva
Keyword(s):  
Light Emission ◽  
Heavy Atom ◽  
Quantum Yields ◽  
Efficient Production ◽  
Triplet States ◽  
Singlet States ◽  
Electronically Excited ◽  
Excited Singlet States ◽  
Thermolysis Reaction ◽  
Effect Of Heavy Atom

Chemi-/bioluminescence are phenomena in which chemical energy is converted into electronically excited singlet states, which decay with light emission. Given this feature, along with high quantum yields and other beneficial characteristics, these systems have gained numerous applications in bioanalysis, in biomedicine, and in the pharmaceutical field. Singlet chemiexcitation is made possible by the formation of cyclic peroxides (as dioxetanones) as thermolysis provides a route for a ground state reaction to produce singlet excited states. However, such thermolysis can also lead to the formation of triplet states. While triplet states are not desired in the typical applications of chemi-/bioluminescence, the efficient production of such states can open the door for the use of these systems as sensitizers in photocatalysis and triplet-triplet annihilation, among other fields. Thus, the goal of this study is to assess the effect of heavy atom addition on the thermolysis and triplet chemiexcitation of a model dioxetanone. Monobromination does not affect the thermolysis reaction but can improve the efficiency of intersystem crossing, depending on the position of monobromination. Addition of bromine atoms to the triplet state reaction product has little effect on its properties, except on its electron affinity, in which monobromination can increase between 3.1 and 8.8 kcal mol−1.

Photolysis of SO2 in the Presence of Foreign Gases. VI. Acetylene and Allene

1974 ◽  
Vol 52 (20) ◽  
pp. 3451-3453 ◽  
Author(s):  
Menachem Luria ◽  
Julian Heicklen
Keyword(s):  
Triplet State ◽  
Gas Phase ◽  
Triplet States ◽  
Relative Importance ◽  
Excited Singlet ◽  
Singlet States ◽  
Excited Singlet States ◽  
Allene System

The photolysis of SO2 at 3130 Å and 25 °C in the presence of C2H2 leads to CO, and, in the presence of allene to CO and C2H4 as gas phase products. In the C2H2 system, the CO comes from the two non-emitting triplet states of SO2, 57% from SO2** and 43% from SO2≠. In the allene system, the two excited singlet states of SO2, and possibly the emitting triplet state, also participate. The relative importance of the contributions from each state can be estimated to be >35% from 1SO2, <16% from 3SO2, 8% from SO2*, 12% from SO2**, and 29% from SO2≠.

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