Wavelength dependence of the multiphoton ionization-fragmentation mass spectrometric pattern of benzaldehyde

Yang, Jinghong; Gobeli, D. A.; Pandolfi, R. S.; El‐Sayed, Mostafa A.

doi:10.1021/j100235a040

Cited by 35 publications

(32 citation statements)

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“…Structural refinements were conducted with each dual model, and again, in each case two long bond distances occurred in the aryl rings, except in the cases where T 2 ͑ * * ͒ benzaldehyde is paired with either benzene and carbon monoxide or the phenyl and formyl radicals. Based on a better 2 and previous experi- mental observations of benzene and carbon monoxide as photoproducts, 11,12,35,[37][38][39] the molecular mixture of benzene, carbon monoxide, and triplet * benzaldehyde were concluded to be the products of this reaction.…”

Section: B Time-resolved Structures: Benzaldehydementioning

confidence: 99%

“…35 In another report, single shots at 266 nm showed no benzene ion signal when the pulse width was 25 ps, but showed a near-unity production of benzene ions when the excitation laser pulse width was 8 ns. 36,37 Using 10 ns pulses at 266 nm in a mass spectrometer Polevoi et al determined the time constant for benzene ion formation to be ϳ30 ns. Their kinetic model predicts that the reaction corresponds to triplet benzaldehyde dissociating into benzene in its own triplet state and ground state carbon monoxide.…”

Section: A Benzaldehydementioning

confidence: 99%

“…Several researchers report no chemistry at all after S 1 excitation. 4,12,14,36,37 Chemistry that is reported is of a fragmentation nature resulting in the benzoyl radical and atomic hydrogen. 22,41 One study notes a slow buildup of polymer on the walls of the gas cell after prolonged exposure at 328 or 365 nm.…”

Section: A Benzaldehydementioning

confidence: 99%

“…In the isolated molecule, at energies above S 2 excitation the expected yield of benzene and carbon monoxide is nearly unity ͑phosphorescence is a minor channel͒. 4,11,37 This unity yield of benzene is actually the sum of two separate benzene-forming reactions: the fast singlet channel and the slow triplet channel.…”

Section: B Spectroscopic Observations Revisitedmentioning

confidence: 99%

“…[35][36][37]39 These inquiries have provided a reaction time scale between 20 ps and 2 ns. In order to unite our UED results with these from the literature, simulations of population evolution have been performed following the photophysical and photochemical mechanisms described in Eq.…”

Section: B Spectroscopic Observations Revisitedmentioning

confidence: 99%

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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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Section: B Time-resolved Structures: Benzaldehydementioning

confidence: 99%

Section: A Benzaldehydementioning

confidence: 99%

Section: A Benzaldehydementioning

confidence: 99%

Section: B Spectroscopic Observations Revisitedmentioning

confidence: 99%

Section: B Spectroscopic Observations Revisitedmentioning

confidence: 99%

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

Park

Feenstra

Zewail

2006

The Journal of Chemical Physics

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Internal energy content ofn-butylbenzene, bromobenzene, iodobenzene and aniline molecular ions generated by two-photon ionization at 266 nm. A photodissociation study

Yoon

Hwang

Choe

et al. 1999

Rapid Commun. Mass Spectrom.

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A technique to investigate photodissociation kinetics on a nanosecond time scale has been devised for molecular ions generated by multiphoton ionization (MPI) using mass-analyzed ion kinetic energy spectrometry. The branching ratio or rate constant has been determined for the photodissociation of the n-butylbenzene, bromobenzene, iodobenzene, and aniline molecular ions generated by MPI at 266 nm. The ion internal energies have been estimated by comparing the measured kinetic data with the previous energy dependence data. The analysis has shown that only those molecular ions generated by two-photon ionization contribute to the photodissociation signals. Around half of the available energy has been found to remain as molecular ion internal energy in the two-photon ionization process. Copyright 1999 John Wiley & Sons, Ltd.

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Die Multiphotonen‐Ionisations(MUPI)‐Massenspektrometrie

Grotemeyer

Schlag

1988

Angewandte Chemie

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Wavelength dependence of the multiphoton ionization-fragmentation mass spectrometric pattern of benzaldehyde

Abstract: well as the kind cooperation of Prof. N. J. Turro with respect to the FPDL. TTiis research was supported by NSF Grant CHE 78-25187.Registry No. Benzene, 71-43-2; fluorobenzene, 462-06-6; iodobenzene, 591-50-4; tert-butylbenzene, 98-06-6.

Cited by 35 publications

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

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

Internal energy content ofn-butylbenzene, bromobenzene, iodobenzene and aniline molecular ions generated by two-photon ionization at 266 nm. A photodissociation study

Die Multiphotonen‐Ionisations(MUPI)‐Massenspektrometrie

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