Single vibronic level fluorescence. III. Fluorescence yields from three vibronic levels in the 1B2u state of benzene

Parmenter, C. S.; Schuyler, Michael

doi:10.1016/0009-2614(70)85090-4

Cited by 85 publications

(27 citation statements)

References 7 publications

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“…Hence, it may prove to be possible to make frequency assignments for triplet vibronic states if the harmonic approximation is invoked. We should note, in this case, that for AWa = + 100 cm-1 the relative rates in 8-naphthylamine very likely conforms to the strong coupling limit with respect to one or more of its modes, i.e., these modes have large geometry and/or frequency changes between the two electronic states involved in the radiation less transition. Table VII were not explored because of the range of errors in experimental results.…”

Section: Llw W(l)/w(o) W(2)/w(0) W(3)/w(0)mentioning

confidence: 74%

Dependence of Radiationless Decay Rates in Polyatomic Molecules upon the Initially Selected Vibronic State: General Theory and Application

Heller

Freed

Gelbart

1972

The Journal of Chemical Physics

191

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Radiationless transition in large isolated molecules: Variation of excess energy dependence of its decay rate with initially prepared electronic state A general scheme for calculating relative nonradiative decay rates of initially selected vibronic levels in polyatomic molecules is developed. Here we are concerned only with relative rates corresponding to initial vibronic states in some particular electronic manifold decaying into some other particular electronic manifold. Therefore we need only consider the exact density-of-states-weighted-Franck-Condon factor accounting for the vibrational contribution to the over-all nonradiative decay rate. This contribution is calculated approximately in the large molecule (statistical) limit by deriving the appropriate (modified) energy gap law. The contributions of "special" modes (e.g., optically excited modes, and modes with large geometry and/or frequency shifts) are partitioned from those of the other modes by techniques similar to ones developed earlier to treat cis-trans isomerism and are calculated explicitly. Excellent agreement with the recent low pressure experimental results of Spears, Abramson, and Rice for the S,--+T, intersystem crossing rates from individual vibronic states in benzene and perdeuterobenzene is obtained, but only by taking proper account of the effects of geometry and frequency changes of the various vibrational modes involved in the transition. The sharp dependence of the relative nonradiative rates for a progression in an optical mode upon the frequency shift in that mode leads to the possibility of evaluating the vibrational frequencies in an electronic state by measuring the radiationless decay rate into that electronic state (e.g., in the benzene case determining T, vibrational frequencies from S,--+T, decay rates). Finally, we comment upon recent low pressure experimental results for /3-naphthylamine, monofluorobenzene, and upon some observed temperature dependences of radiationless transition rates in matrices.

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Section: Llw W(l)/w(o) W(2)/w(0) W(3)/w(0)mentioning

confidence: 74%

Dependence of Radiationless Decay Rates in Polyatomic Molecules upon the Initially Selected Vibronic State: General Theory and Application

Heller

Freed

Gelbart

1972

The Journal of Chemical Physics

191

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“…The rich photophysics of benzene can briefly be summarized as follows: Resonant excitation to S 1 is followed by fluorescence and a slow (nanosecond timescale) ISC pathway, 52–56 and these channels are often referred to as channel 1 and channel 2, respectively. When the excitation energy is increased 3000 cm −1 above the S 1 onset, the fluorescence yield decreases drastically due to activation of a third channel (the controversial “channel 3” first reported by Callomon in the 1960s 57 ), which has been identified as an ultrafast non-radiative process of IC and/or ISC character 58–62 .…”

Section: Introductionmentioning

confidence: 99%

Distortion dependent intersystem crossing: A femtosecond time-resolved photoelectron spectroscopy study of benzene, toluene, and p-xylene

Stephansen¹,

Sølling²

2017

Structural Dynamics

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The competition between ultrafast intersystem crossing and internal conversion in benzene, toluene, and p-xylene is investigated with time-resolved photoelectron spectroscopy and quantum chemical calculations. By exciting to S2 out-of-plane symmetry breaking, distortions are activated at early times whereupon spin-forbidden intersystem crossing becomes (partly) allowed. Natural bond orbital analysis suggests that the pinnacle carbon atoms distorting from the aromatic plane change hybridization between the planar Franck-Condon geometry and the deformed (boat-shaped) S2 equilibrium geometry. The effect is observed to increase in the presence of methyl-groups on the pinnacle carbon-atoms, where largest extents of σ and π orbital-mixing are observed. This is fully consistent with the time-resolved spectroscopy data: Toluene and p-xylene show evidence for ultrafast triplet formation competing with internal conversion, while benzene appears to only decay via internal conversion within the singlet manifold. For toluene and p-xylene, internal conversion to S1 and intersystem crossing to T3 occur within the time-resolution of our instrument. The receiver triplet state (T3) is found to undergo internal conversion in the triplet manifold within ≈100–150 fs (toluene) or ≈180–200 fs (p-xylene) as demonstrated by matching rise and decay components of upper and lower triplet states. Overall, the effect of methylation is found to both increase the intersystem crossing probability and direct the molecular axis of the excited state dynamics.

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“…When exciting with light that is 3000 cm À1 above the 0-0 transition energy, the fluorescence quantum yield dropped dramatically (compared to excitation with light at the 0-0 transition energy) from about 0.2 to less than 0.001. [6][7][8] This behavior has been explained by the presence of a conical intersection between S 0 and S 1 , which can facilitate very fast, non-radiative transfer between electronic states, and the process has been termed ''channel three''. 9 This intersection, however, is not directly accessible from the excitation region: a barrier must first be overcome, which is the origin of the dependence of the fluorescence on the excitation energy.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved photoelectron spectroscopy from first principles: Excited state dynamics of benzene

Thompson

Martı́nez

2011

Faraday Discuss.

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We use the ab initio multiple spawning (AIMS) method to follow the dynamics of benzene after excitation to the second singlet excited state (S2). The results are validated by comparison to potential energy surfaces including dynamical electron correlation effects. Time-resolved photoelectron spectra are computed and compared to experimental results. Simulations agree with experiment that there are both short-lived and long-lived components of the excited state population. We show that these components both originate from quenching through the same S2/S1 conical intersection and that the difference between them comes from their behavior immediately after decay to S1. This is presumed to be a function of the details of the way in which the S2/S1 intersection region is accessed; for example, the momentum distribution and the topology of the seam in the relevant region.

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Single vibronic level fluorescence. III. Fluorescence yields from three vibronic levels in the 1B2u state of benzene

Cited by 85 publications

References 7 publications

Dependence of Radiationless Decay Rates in Polyatomic Molecules upon the Initially Selected Vibronic State: General Theory and Application

Dependence of Radiationless Decay Rates in Polyatomic Molecules upon the Initially Selected Vibronic State: General Theory and Application

Distortion dependent intersystem crossing: A femtosecond time-resolved photoelectron spectroscopy study of benzene, toluene, and p-xylene

Time-resolved photoelectron spectroscopy from first principles: Excited state dynamics of benzene

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