Photochemistry of the fluorotoluenes. I. Quantum yields of fluorescence and intersystem crossing in 1-fluoro-2-, 1-fluoro-3-, and 1-fluoro-4-methylbenzenes

1971 ◽  
Vol 75 (21) ◽  
pp. 3214-3220 ◽  
Author(s):  
Khalid Al-Ani ◽  
David Phillips
Keyword(s):  
Quantum Yields ◽  
Intersystem Crossing

The Photolysis in Acidic Aqueous Solutions of the Monooxalato-bisethylenediamine Chromium(III) Cation and the Bisoxalatomonoethylenediamine Chromate(III) Anion: Photolysis Modes and Quantum Yields

1971 ◽  
Vol 49 (3) ◽  
pp. 375-383 ◽  
Author(s):  
A. D. Kirk ◽  
K. C. Moss ◽  
J. G. Valentin
Keyword(s):  
Quantum Yield ◽  
Aqueous Solutions ◽  
Quantum Yields ◽  
Ligand Field ◽  
Intersystem Crossing ◽  
Empirical Correlations ◽  
Complex Ions ◽  
Ethylenediamine Complex ◽  
Ethylenediamine Ligand ◽  
Ph Range

The photolysis reactions of the complex ions [Cr(en)2ox]+ and [Cren(ox)2]− have been studied in the pH range 1 → 3 and at temperatures from 0 to 25 °C. It has been found that both ions photoaquate to a monodentate protonated ethylenediamine complex which then undergoes further aquation thermally with loss of the ethylenediamine ligand. Quantum yields for these aquations were measured for irradiation into the ligand field bands, the values obtained being 0.18 and 0.02, respectively. The results are discussed in terms of known empirical correlations for Cr(III) complexes. Assuming these reactions may occur from the 4T2g state as precursor, arguments are presented that the correlation between quantum yield and ΔE may depend on mixing of the 4T2g and 2Eg states, and its effect on the intersystem crossing rate constant.

Luminescence of 5-Phenyltetrazole and its Derivatives. Part II. Phosphorescence

1984 ◽  
Vol 39 (6) ◽  
pp. 556-559 ◽  
Author(s):  
I. Gryczyński ◽  
A. Kawski ◽  
Z. Grzonka ◽  
A. Rażyńska
Keyword(s):  
Triplet State ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Thermal Deactivation ◽  
Fluorescence Quantum Yields ◽  
Radiative Transitions ◽  
Polyvinyl Alcohol Film ◽  
Methyl Derivatives ◽  
Temperature Responses ◽  
Phosphorescence Spectra

The phosphorescence spectra, mean lifetimes of phosphorescence and ratios of phosphorescence/ fluorescence quantum yields have been measured for 5-phenyltetrazole and its three methyl derivatives in a polyvinyl alcohol film over the temperature range of (77-250) K. Temperature responses of the non-radiative intersystem crossing constant. KST, and the non-radiative triplet state deactivation constant, km, have been investigated on the basis of these measurements. The energy of activation for the non-radiative transitions has been determined. With the methyl 5-phenyltetrazoles, the thermal deactivation of the triplet state, contrary to the intersystem crossing, has been found to be influenced by the position of the methyl substituent in the phenyl ring.

Photochemistry of cyclododecanone

1976 ◽  
Vol 29 (11) ◽  
pp. 2477 ◽  
Author(s):  
PJ Burchill ◽  
AG Kelso ◽  
AJ Power
Keyword(s):  
Cleavage Product ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Quantitative Measurements ◽  
Acyclic Ketones ◽  
Triplet Lifetime

Quantitative measurements of the photolytic reactions of cyclododecanone gave quantum yields of reaction and of intersystem crossing as 0.56 and 0.88 respectively, and a triplet lifetime of 1.7 x 10-7 s. Cyclobutanol formation accounts for most of the reaction with only a low yield of the Norrish II cleavage product; this contrasts markedly with the opposite behaviour of acyclic ketones of similar size. The results may be explained by the apparent restriction of rotation in cyclododecanone molecules.

scholarly journals Exploiting radical-pair intersystem crossing for maximizing singlet oxygen quantum yields in pure organic fluorescent photosensitizers

2020 ◽  
Vol 11 (40) ◽  
pp. 10921-10927
Author(s):  
Xuanhang Wang ◽  
Yucong Song ◽  
Guocui Pan ◽  
Wenkun Han ◽  
Boyu Wang ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Radical Pair ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Molecular Symmetry

Maximizing singlet oxygen quantum yields of a fluorescent photosensitizer for realizing approximately 100% utilization of excitons by precisely controlling the molecular symmetry.

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