Transient absorption and vibrational relaxation dynamics of the lowest excited singlet state of pyrene in solution

Foggi, Paolo; Pettini, Luca; Sánta, Imre; Righini, Roberto; Califano, S.

doi:10.1021/j100019a029

Cited by 66 publications

(88 citation statements)

References 13 publications

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“…Figure 2 shows the temporal evolution of the pump±probe spectrum of PydC in water at pH 5 in the time range of 2 to 20 ps after excitation. These spectra are dominated by the typical transient absorption of the lowest excited singlet state of pyrenyl derivatives [29] and the pyrenyl radical cation. [30] The peak maximum at 375 nm corresponds to the S 1 !S n absorption of pyrene.…”

Section: Resultsmentioning

confidence: 99%

Ultrafast Proton‐Coupled Electron‐Transfer Dynamics in Pyrene‐Modified Pyrimidine Nucleosides: Model Studies towards an Understanding of Reductive Electron Transport in DNA

et al. 2004

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5-(Pyren-1-yl)-2'-deoxyuridine (PydU) and 5-(Pyren-1-yl)-2'-deoxycytidine (PydC) were used as model nucleosides for DNA-mediated reductive electron transport (ET) in steady-state fluorescence and femtosecond time-resolved transient absorption spectroscopy studies. Excitation of the pyrene moiety in PydU and PydC leads to an intramolecular electron transfer that yields the pyrenyl radical cation and the corresponding pyrimidine radical anion (dU.- and dC.-. By comparing the excited state dynamics of PydC and PydU, we derived information about the energy difference between the two pyrimidine radical anion states. To determine the influence of protonation on the rates of photoinduced intramolecular ET, the spectroscopic investigations were performed in acetonitrile, MeCN, and in water at different pH values. The results show a significant difference in the basicity of the generated pyrimidine radical anions and imply an involvement of proton transfer during electron hopping in DNA. Our studies revealed that the radical anion dC.- is being protonated even in basic aqueous solution on a picosecond time scale (or faster). These results suggest that protonation of dC.- may also occur in DNA. In contrast, efficient ET in PydU could only be observed at low pH values (< 5). In conclusion, we propose--based on the free energy differences and the different basicities--that only dT.- but not dC.- can participate as an intermediate charge carrier for excess electron migration in DNA.

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Section: Resultsmentioning

confidence: 99%

Ultrafast Proton‐Coupled Electron‐Transfer Dynamics in Pyrene‐Modified Pyrimidine Nucleosides: Model Studies towards an Understanding of Reductive Electron Transport in DNA

et al. 2004

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“…In photoluminescence lifetime measurements the decay of the number of excited emitters is probed by recording a photoluminescence decay curve ͓f͑t͔͒. The number of excited emitters c͑t͒ can be probed directly by transient absorption measurements [16][17][18] and nonradiative decay ͑g − f͒͑t͒ can be recorded with photothermal techniques 19,20 ͑see Fig. 1͒.…”

Section: Introductionmentioning

confidence: 99%

“…However, in many cases the decay is much more complex and strongly differs from singleexponential decay. 4,15,16,[21][22][23][24][25] This usually means that the decay is characterized by a distribution of rates instead of a FIG. 1.…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of time-resolved emission from ensembles of semiconductor quantum dots: Interpretation of exponential decay models

et al. 2007

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We present a statistical analysis of time-resolved spontaneous emission decay curves from ensembles of emitters, such as semiconductor quantum dots, with the aim of interpreting ubiquitous non-single-exponential decay. Contrary to what is widely assumed, the density of excited emitters and the intensity in an emission decay curve are not proportional, but the density is a time integral of the intensity. The integral relation is crucial to correctly interpret non-single-exponential decay. We derive the proper normalization for both a discrete and a continuous distribution of rates, where every decay component is multiplied by its radiative decay rate. A central result of our paper is the derivation of the emission decay curve when both radiative and nonradiative decays are independently distributed. In this case, the well-known emission quantum efficiency can no longer be expressed by a single number, but is also distributed. We derive a practical description of non-single-exponential emission decay curves in terms of a single distribution of decay rates; the resulting distribution is identified as the distribution of total decay rates weighted with the radiative rates. We apply our analysis to recent examples of colloidal quantum dot emission in suspensions and in photonic crystals, and we find that this important class of emitters is well described by a log-normal distribution of decay rates with a narrow and a broad distribution, respectively. Finally, we briefly discuss the Kohlrausch stretched-exponential model, and find that its normalization is ill defined for emitters with a realistic quantum efficiency of less than 100%.

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“…On the basis of the available literature on pyrene, it is evident that after 1 ps the excited state population has decayed to the dark L b state minimum 1 (L b ) min where it remains trapped on a time scale much longer than the duration of the experiment. 40,41,45 Consequently, the appearing ESA signals are caused by electronic promotion out of the 1 (L b ) min .…”

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confidence: 99%

Spectral lineshapes in nonlinear electronic spectroscopy

Nenov

Giussani

Fingerhut

et al. 2015

Phys. Chem. Chem. Phys.

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We outline a computational approach for nonlinear electronic spectra, which accounts for the electronic energy fluctuations due to nuclear degrees of freedom and explicitly incorporates the fluctuations of higher excited states, induced by the dynamics in the photoactive state(s). This approach is based on mixed quantum-classical dynamics simulations. Tedious averaging over multiple trajectories is avoided by employing the linearly displaced Brownian harmonic oscillator to model the correlation functions. The present strategy couples accurate computations of the high-lying excited state manifold with dynamics simulations. The application is made to the two-dimensional electronic spectra of pyrene, a polycyclic aromatic hydrocarbon characterized by an ultrafast (few tens of femtoseconds) decay from the bright S 2 state to the dark S 1 state. The spectra for waiting times t 2 = 0 and t 2 = 1 ps demonstrate the ability of this approach to model electronic state fluctuations and realistic lineshapes. Comparison with experimental spectra [Krebs et al., New Journal of Physics, 2013, 15, 085016] shows excellent agreement and allows us to unambiguously assign the excited state absorption features.

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Transient absorption and vibrational relaxation dynamics of the lowest excited singlet state of pyrene in solution

Cited by 66 publications

References 13 publications

Ultrafast Proton‐Coupled Electron‐Transfer Dynamics in Pyrene‐Modified Pyrimidine Nucleosides: Model Studies towards an Understanding of Reductive Electron Transport in DNA

Ultrafast Proton‐Coupled Electron‐Transfer Dynamics in Pyrene‐Modified Pyrimidine Nucleosides: Model Studies towards an Understanding of Reductive Electron Transport in DNA

Statistical analysis of time-resolved emission from ensembles of semiconductor quantum dots: Interpretation of exponential decay models

Spectral lineshapes in nonlinear electronic spectroscopy

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