Lifetime studies of the biacetyl excited singlet and triplet states in the gas phase at 25.deg.

1972 ◽  
Vol 94 (1) ◽  
pp. 13-19 ◽  
Author(s):  
Howard W. Sidebottom ◽  
Charles C. Badcock ◽  
Jack G. Calvert ◽  
Blaine R. Rabe ◽  
Edward K. Damon
Keyword(s):  
Gas Phase ◽  
Triplet States ◽  
Excited Singlet ◽  
Singlet And Triplet States ◽  
Lifetime Studies

The mechanism of the gas phase photolysis of acetone

1966 ◽  
Vol 290 (1423) ◽  
pp. 563-582 ◽  
Keyword(s):  
Gas Phase ◽  
Order Rate Constant ◽  
Electronic Energy ◽  
Intersystem Crossing ◽  
Triplet States ◽  
Excited Singlet ◽  
First Order ◽  
Electronic Energy Transfer ◽  
Vibrational Levels ◽  
Singlet And Triplet States

A mechanism for the photolysis of acetone has been derived from experimental data including studies on the photosensitized isomerization of olefines. Dissociation into methyl and acetyl radicals occurs from both the first excited singlet and triplet states; the rate constants for excitation by light of 3130 Å wavelength are 2.5 x 10 16 exp ( —16900/ RT ) and 2.5 x 10 10 exp ( — 6400/ RT ) 1. mole -1 s -1 respectively. At low intensities of absorption, decomposition of acetyl radicals predominates over radical-radical interactions. The triplet state is extensively populated at moderate temperatures, the yield at 48 °C being 0.98. The low phosphorescence efficiency of acetone can be ascribed to intersystem crossing to the ground state for which the first order rate constant is 1.25 x 10 5 s -1 . The isomerization data requires the recognition of at least two vibrational levels of the acetone triplet, the rate of electronic energy transfer depending upon the excess energy possessed by the donor

Emission and Deactivation of the Excited States of 2,3-Pentanedione

1972 ◽  
Vol 50 (9) ◽  
pp. 1338-1344 ◽  
Author(s):  
A. W. Jackson ◽  
A. J. Yarwood
Keyword(s):  
Triplet State ◽  
Gas Phase ◽  
Excited States ◽  
Singlet State ◽  
Triplet States ◽  
Excited Singlet ◽  
Vibrationally Excited ◽  
Singlet Level ◽  
Singlet And Triplet States ◽  
Fluorescence And Phosphorescence

Vibrationally excited singlet and triplet states of 2,3-pentanedione are formed by photolysis at 365 nm. The processes removing these excited states in the gas phase are studied by measuring the fluorescence and phosphorescence yields. Fluorescence can occur from the vibrationally excited, as well as the vibrationally equilibrated, singlet state. The fluorescence and phosphorescence data are considered in terms of mechanisms which involve either weak or strong collisions. Although the data cannot distinguish between the alternatives, there are two significant conclusions. The fluorescence data require that emission occur from at least two levels in the singlet manifold. To explain the phosphorescence data, the highest emitting singlet level must not lead to a vibrationally equilibrated triplet state.

scholarly journals Organic molecules with inverted gaps between first excited singlet and triplet states and appreciable fluorescence rates

Matter ◽  
2021 ◽  
Author(s):  
Robert Pollice ◽  
Pascal Friederich ◽  
Cyrille Lavigne ◽  
Gabriel dos Passos Gomes ◽  
Alán Aspuru-Guzik
Keyword(s):  
Organic Molecules ◽  
Triplet States ◽  
Excited Singlet ◽  
Singlet And Triplet States

Photochemical reactions of 2,2?-furil. Solvent dependent photoreduction via the lowest excited singlet and triplet states

1992 ◽  
Vol 5 (6) ◽  
pp. 355-360 ◽  
Author(s):  
Hiroyasu Inoue ◽  
Tadamitsu Sakurai ◽  
Toshihiko Hoshi ◽  
Isao Ono ◽  
Jun Okubo
Keyword(s):  
Photochemical Reactions ◽  
Triplet States ◽  
Excited Singlet ◽  
Singlet And Triplet States

scholarly journals The Tautomeric Conformers for the Molecules of Guanine and Cytosine. Some Rem arks about Their Stability

1977 ◽  
Vol 32 (9-10) ◽  
pp. 870-873 ◽  
Author(s):  
Julio Marañon ◽  
Oscar M. Sorarrain
Keyword(s):  
Experimental Data ◽  
Triplet States ◽  
Excited Singlet ◽  
Singlet And Triplet States ◽  
Semi Empirical

Abstract In this paper we seek to determine the shape of the barrier between the normal and tautomeric conformers for some excited singlet and triplet states in the molecules of guanine and cytosine. The molecules are considered isolated and a particular movement of the H atom is analysed.The semi-empirical CNDO/2-CI has been used. The calculated results are compared with the available experimental data.

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