Solution Phase Isomerization of Vibrationally Excited Singlet Nitrenes to Vibrationally Excited 1,2-Didehydroazepine

2006 ◽  
Vol 128 (46) ◽  
pp. 14804-14805 ◽  
Author(s):  
Gotard T. Burdzinski ◽  
Chris T. Middleton ◽  
Terry L. Gustafson ◽  
Matthew S. Platz
Keyword(s):  
Solution Phase ◽  
Excited Singlet ◽  
Vibrationally Excited

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.

The effect of temperature, pressure, and excitation wavelength on the photoluminescence of acetaldehyde vapour

1973 ◽  
Vol 333 (1594) ◽  
pp. 385-402 ◽  
Keyword(s):  
Vibrational Energy ◽  
Singlet State ◽  
Energy Content ◽  
Excited Singlet State ◽  
Effect Of Temperature ◽  
Excitation Wavelength ◽  
Triplet States ◽  
Excited Singlet ◽  
Vibrationally Excited ◽  
Electronically Excited

A study of the effect of acetaldehyde, trans -butene-2, and isobutane pressure on the fluorescence and phosphorescence emissions from acetaldehyde vapour has been made. The results have been interpreted in terms of electronically excited singlet and triplet states, in the behaviour of which vibrational energy content plays a crucial role. The extent to which the initially formed excited state undergoes predissociation, or is collisionally deactivated, has been examined from 254 to 340 nm between 20 and 99°C. At the longer excitation wavelengths the effect of pressure on emission yields indicates that collisional deactivation to the vibrationally equilibrated levels of the excited singlet state followed by intersystem crossing to the triplet state is the predominant mode for energy dissipation. At shorter excitation wavelengths predissociation becomes of increasing importance. Collisional deactivation of excited singlet acetaldehyde molecules by acetaldehyde and trans -butene-2 occurs by a single stage mechanism, in contrast to isobutane, and the possibility of complex formation is discussed. Relative rates for collisional deactivation by butene-2 and acetaldehyde of vibrationally excited acetaldehyde molecules in the first excited singlet state have been determined and shown to vary as a function of excitation wavelength.

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