Heavy-atom effects on the excited singlet-state electron-transfer reaction

1991 ◽  
Vol 95 (1) ◽  
pp. 38-42 ◽  
Author(s):  
Koichi Kikuchi ◽  
Masato Hoshi ◽  
Taeko Niwa ◽  
Yasutake Takahashi ◽  
Tsutomu Miyashi
Keyword(s):  
Electron Transfer ◽  
Transfer Reaction ◽  
Singlet State ◽  
Heavy Atom ◽  
Electron Transfer Reaction ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
State Electron

Electrochemiluminescence of Phenanthrene-d10: A Possible Case of Efficient Triplet–Triplet Annihilation

1975 ◽  
Vol 53 (1) ◽  
pp. 76-78 ◽  
Author(s):  
N. Periasamy ◽  
K. S. V. Santhanam
Keyword(s):  
Electron Transfer ◽  
Transfer Reaction ◽  
Singlet State ◽  
Electron Transfer Reaction ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
Triplet Triplet Annihilation

Electrochemiluminescence (e.c.1.) of mixed phenanthrene(Ph)-d10-oxidant and Ph-h10-oxidant systems have been studied. Emission from excited singlet state of Ph-d10 or Ph-h10 is observed. On the basis of energetics of the electron transfer reaction, triplet-triplet annihilation is postulated to give the excited singlet state of Ph. Comparison of these results with photoluminescence of Ph-d10, shows efficient triplet–triplet annihilation occurs in e.c.1.

Fluorescence of chloropentafluoroacetone

1970 ◽  
Vol 48 (16) ◽  
pp. 2611-2616 ◽  
Author(s):  
H. S. Samant ◽  
A. J. Yarwood
Keyword(s):  
Rate Constant ◽  
High Pressures ◽  
Singlet State ◽  
Radiative Lifetime ◽  
Heavy Atom ◽  
Excited Singlet State ◽  
Intersystem Crossing ◽  
Excited Singlet ◽  
Gaseous State ◽  
Fluorescent State

The fluorescence of chloropentafluoroacetone in the gaseous state at room temperature is reported. The fluorescence extends from 337 nm to greater than 560 nm with a maximum intensity at 420 nm and is unaffected by low pressures of oxygen. The energy of the first excited singlet state is estimated as about 83 kcal and the fluorescence data for 313 and "290" nm excitation indicate that fluorescence enhancement occurs as the pressure increases. The fluorescent yield at high pressures [Formula: see text] is independent of the nature of the gas used to attain the high pressure. The lifetime of the fluorescent state is 35.1 ± 0.3 ns.A simple mechanism correlates the experimental observations and the values of the rate constants are considered. The reciprocal of the natural radiative lifetime is calculated to be 6.6 × 105 s−1 and the rate constant assigned to intersystem crossing to the triplet is 2.8 × 107 s−1. A comparison with the data in the literature for hexafluoroacetone shows the effect of substitution by a heavy atom in the fluorinated ketone. It about doubles the value of the rate constant associated with intersystem crossing from the first excited singlet state in the gas phase.

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