Energy and time dependence of the decay processes of toluene molecular cations

Bombach, Rolf; Dannacher, Josef; Stadelmann, Jean Pierre

doi:10.1021/ja00351a014

Cited by 54 publications

(69 citation statements)

References 1 publication

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“…18 The appearance energy of the C 5 H 5 ϩ fragment starting from the neutral toluene molecule is 14.55 eV, but for detection times of the order of 10 s, it appears only beyond ϳ16 eV. 18 In our experiments, the C 5 H 5 ϩ fragment is not observed; this fact is consistent with our multiple-order MPI model, as will be shown below. Rate-energy functions k(E int ) for the unimolecular decay reaction ͑10͒ are given in Refs.…”

Section: ϫ2supporting

confidence: 86%

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Photoionization and photofragmentation of gaseous toluene using 80-fs, 800-nm laser pulses

Müller

Uiterwaal

Witzel

et al. 2000

The Journal of Chemical Physics

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This paper presents ion yields resulting from multiphoton ionization and fragmentation of gaseous toluene (C 7 H 8 ) in the focus of an 80 fs Ti:sapphire laser beam (ϭ800 nm) with a sufficiently small B-integral ͓Siegman, Lasers ͑University Science Books, Mill Valley, CA, 1986͔͒. The peak intensity was varied between 1.9ϫ10 13 and 2.8ϫ10 14 W cm Ϫ2 , and both linear and circular polarization were used. Over the whole range of intensities studied, only the singly charged parent ion and its fragment, C 7 H 7 ϩ , are found. Although the Keldysh adiabaticity parameter equals 0.86 for the saturation intensity of ϳ1ϫ10 14 W cm Ϫ2 , there is no indication of tunneling. The parent ion yield is found to be effectively proportional to the sixth power of the peak intensity. This is shown to be in good agreement with a multiple lowest-order perturbation multiphoton ionization model which takes into account successive channel closing for increasing peak intensities and orders up to 11 inclusive. On the assumption that the excess energy acquired by the toluene cation as a result of the interaction with the electromagnetic field is of the order of the ponderomotive energy for the intensity prevailing at the moment of the ionization, the internal energy distribution of the toluene cations created that is brought about by this multiple-order multiphoton ionization model is calculated. This internal energy distribution is in perfect agreement with the measured C 7 H 7 ϩ yield, if the rate-energy curve for the fragmentation of excited toluene cations as given by Golovin et al. ͓Sov. J. Chem. Phys. 2, 632 ͑1985͔͒ is moderately reduced by a factor of 4.5.

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Section: ϫ2supporting

confidence: 86%

“…We will now demonstrate how our fragmentation data support our multiple-order MPI model with orders up to 11 inclusive. Fragmentation of the excited toluene cation is known 18 to produce two isomers of C 7 H 7 ϩ , tropylium and benzylium. Since our TOF method merely detects mass/charge ratios, this fragmentation can be symbolically written as…”

Section: ϫ2mentioning

confidence: 99%

Photoionization and photofragmentation of gaseous toluene using 80-fs, 800-nm laser pulses

Müller

Uiterwaal

Witzel

et al. 2000

The Journal of Chemical Physics

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“…These are also the most prominent ions in electron ionization and photoionization mass spectra of toluene in the gas phase. [11][12][13] Fragment ions other than C 7 H 7 + are relatively minor products in the mass spectrum of gaseous toluene. [11][12][13] Among these more scarce ions the most abundant is at m/z = 65, which corresponds to C 5 H 5 + .…”

Section: Mass Spectrometrymentioning

confidence: 99%

“…[11][12][13] Fragment ions other than C 7 H 7 + are relatively minor products in the mass spectrum of gaseous toluene. [11][12][13] Among these more scarce ions the most abundant is at m/z = 65, which corresponds to C 5 H 5 + . This product is also readily seen in our mass spectra recorded for toluene in helium droplets, as illustrated in the expanded view in Figure 1.…”

Section: Mass Spectrometrymentioning

confidence: 99%

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Electronic Spectroscopy of Toluene in Helium Nanodroplets: Evidence for a Long-Lived Excited State

et al. 2013

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Optical excitation of toluene to the S 1 electronic state in helium nanodroplets is found to alter the rate of production of the fragment ions C 7 H 7 + and C 5 H 5 + when the droplets are subjected to subsequent electron ionization. The optical excitation process reduces the abundance of C 7 H 7 + ions delivered into the gas phase whereas C 5 H 5 + ions become more abundant beyond a minimum droplet size. This process contrasts with normal optical depletion spectroscopy, where the optical absorption of a molecular dopant in a helium nanodroplet shrinks the helium droplet, and thus the electron impact cross sections, because of dissipation of the absorbed energy by evaporative loss of helium atoms. The observations here are interpreted in terms of formation of an excited state in the neutral molecule which survives for several hundred µs.This long-lived excited state, which is assumed to be the lowest triplet electronic state, shows different cross sections for production of C 7 H 7 + and C 5 H 5 + relative to the S 0 state.

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ChemInform Abstract: ENERGY AND TIME DEPENDENCE OF THE DECAY PROCESSES OF TOLUENE MOLECULAR CATIONS

Bombach¹,

Dannacher²,

Stadelmann³

1983

Chemischer Informationsdienst

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Energy and time dependence of the decay processes of toluene molecular cations

Cited by 54 publications

References 1 publication

Photoionization and photofragmentation of gaseous toluene using 80-fs, 800-nm laser pulses

Photoionization and photofragmentation of gaseous toluene using 80-fs, 800-nm laser pulses

Electronic Spectroscopy of Toluene in Helium Nanodroplets: Evidence for a Long-Lived Excited State

ChemInform Abstract: ENERGY AND TIME DEPENDENCE OF THE DECAY PROCESSES OF TOLUENE MOLECULAR CATIONS

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