Triplet-state dynamics at low pressures as studied by electron-impact-induced phosphorescence: Acetophenone

Inoue, A.; Ushiyama, M.; Ebara, Nozomu

doi:10.1016/0009-2614(85)80396-1

Cited by 7 publications

(1 citation statement)

References 9 publications

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“…30,31 Like for benzaldehyde, the prolific study of acetophenone is largely due to its intense phosphorescence facilitated by efficient intersystem crossing from S 1 into the triplet manifold. The photophysics of acetophenone have been studied in the gas phase, [6][7][8][9]20,26,[43][44][45][46][47] solution, 21,48 and in matrices. 22,23,44 Phosphorescence detected in the vapor phase is seen to decrease in intensity with increasing photon energy and exhibits a drop-off as excitation approaches S 2 .…”

Section: B Acetophenonementioning

confidence: 99%

Ultrafast electron diffraction: Excited state structures and chemistries of aromatic carbonyls

Park

Feenstra

Zewail

2006

The Journal of Chemical Physics

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The photophysics and photochemistry of molecules with complex electronic structures, such as aromatic carbonyls, involve dark structures of radiationless processes. With ultrafast electron diffraction ͑UED͒ of isolated molecular beams it is possible to determine these transient structures, and in this contribution we examine the nature of structural dynamics in two systems, benzaldehyde and acetophenone. Both molecules are seen to undergo a bifurcation upon excitation ͑S 2 ͒. Following femtosecond conversion to S 1 , the bifurcation leads to the formation of molecular dissociation products, benzene and carbon monoxide for benzaldehyde, and benzoyl and methyl radicals for acetophenone, as well as intersystem crossing to the triplet state in both cases. The structure of the triplet state was determined to be "quinoidlike" of * character with the excitation being localized in the phenyl ring. For the chemical channels, the product structures were also determined. The difference in photochemistry between the two species is discussed with respect to the change in large amplitude motion caused by the added methyl group in acetophenone. This discussion is also expanded to compare these results with the prototypical aliphatic carbonyl compounds, acetaldehyde and acetone. From these studies of structural dynamics, experimental and theoretical, we provide a landscape picture for, and the structures involved in, the radiationless pathways which determine the fate of molecules following excitation. For completeness, the UED methodology and the theoretical framework for structure determination are described in this full account of an earlier communication ͓J. S. Feenstra et al., J. Chem. Phys. 123, 221104 ͑2005͔͒.

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