Photoionization of diphenylhexatriene and diphenylbutadiene ion radicals in various polar solvents by using time-resolved resonance CARS

Kamisuki, Toshio; Dudev, Todor; Hirose, Chiaki

doi:10.1021/j100168a026

Cited by 11 publications

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“…In agreement with these observations, Wang and McGimpsey reported two-photon generation of the radical cation (DPH •+ , 590 nm) in acetonitrile solution and its absence in cyclohexane . A strong solvent dependence of the efficiency of DPH photoionization to yield DPH radical cations and radical anions was also revealed by time-resolved resonance coherent anti-Stokes Raman scattering measurements …”

Section: Introductionsupporting

confidence: 64%

“…However, DPH radical ion pairs, formed in this way in AN, would separate to give free radical ions, and significant quenching of excimer emission in that solvent would be expected. Also, DPH radical anions are quenched preferentially by oxygen in AN, 18 but the fluorescence behavior of DPH in AN is very similar to that in MCH. Furthermore, the λ max ) 489 ( 1 nm of the analogously derived emission in AN is blue-shifted relative to MCH and does not reveal the stabilization expected for a contact radical ion pair in the more polar solvent.…”

Section: Resultsmentioning

confidence: 90%

“…A possible scenario would involve photoionization of S 1 DPH with the second photon and capture of the ejected electron by a ground-state DPH molecule. 18 An encounter between radical cation and radical anion DPH molecules, formed in proximity, could generate an excimer and account for the structureless new emission. The alternative of ground-state association of DPH molecules is not likely because the DPH absorption spectrum is independent of concentration in MCH for the entire concentration range employed in these measurements.…”

Section: Resultsmentioning

confidence: 99%

“…Since formation of DPH radical cations is known to be biphotonic, , it is tempting to seek an explanation that connects the two phenomena. A possible scenario would involve photoionization of S 1 DPH with the second photon and capture of the ejected electron by a ground-state DPH molecule . An encounter between radical cation and radical anion DPH molecules, formed in proximity, could generate an excimer and account for the structureless new emission.…”

Section: Resultsmentioning

confidence: 99%

“…17 A strong solvent dependence of the efficiency of DPH photoionization to yield DPH radical cations and radical anions was also revealed by time-resolved resonance coherent anti-Stokes Raman scattering measurements. 18 In this paper we describe the excitation pulse intensity dependence of the luminescence response of DPH at 298 K in methylcyclohexane (MCH) and acetonitrile (AN). Effects of O 2 and fumaronitrile on the DPH spectra aid the interpretation of our observations.…”

Section: Introductionmentioning

confidence: 99%

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Distortion of the Fluorescence Spectrum of all-trans-1,6-Diphenyl-1,3,5-hexatriene with Increasing Laser Pulse Excitation Energies

1999

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At high laser pulse excitation energies the fluorescence spectrum of all-trans-1,6-diphenyl-1,3,5-hexatriene, DPH, undergoes distortion that can be modeled as the development of a new broad fluorescence, λ max ) 497 nm, which builds up biphotonically with increasing excitation laser pulse power. This phenomenon is observed upon excitation at either 266 or 355 nm in a variety of organic solvents, provided [DPH] and excitation intensity are sufficiently high. Four possible sources for the distortion of the fluorescence spectrum are investigated: (1) excimer emission arising from DPH radical cation/anion pairs, (2) bicimer fluorescence from the encounter of two S 1 states, (3) S n f S 1 fluorescence, and (4) self-absorption due to overlap of the fluorescence with transient absorption spectra. The first three possibilities are ruled out. The fourth is viable, revealing an effective transient absorption spectrum that agrees well with the known S n r S 1 absorption spectrum at long wavelengths.

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Section: Introductionsupporting

confidence: 64%

Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Distortion of the Fluorescence Spectrum of all-trans-1,6-Diphenyl-1,3,5-hexatriene with Increasing Laser Pulse Excitation Energies

1999

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Experimental and theoretical coherent anti-Stokes Raman scattering studies on triplet excited anthracene

Funk

Schmitt

Kiefer

et al. 2000

J. Raman Spectrosc.

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Transient resonance coherent stokes Raman scattering spectra of photoinduced radical ions of diphenyloctatetraene in polar solvents

Kamisuki

Hirose

1995

J Raman Spectroscopy

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Transient resonance coherent Stokes Raman scattering (CSRS) spectra of the photoinduced radical ions of alltrans-1,8-diphenylocta-1,3,5,7-tetraene (DPO) were observed in polar solvents such as acetonitrile, N,Ndimethylformamide and dimethyl sulphoxide. The identification was based on the long lifetimes and the dependence of their formation on the electron-donating and/or -accepting nature of the solvents. The fluorescence spectra of DPO were also observed in the presence of N,N-dimethylaniline (DMA) and p-dicyanobenzene (DCNB) in pdioxane and in polar solvents without DCNB and DMA. The absence of an indication of exciplex formation, in contrast to the cases of diphenylbutadiene and diphenylhexatriene, can be related to the extremely low efficiency of the radical ion formation by solvent-assisted photoionization in DPO-DMA and DPO-DCNB in p-dioxane systems. The strong dependence of the CSRS signal of the DPO radical ions on the content of polar solvent in the highconcentration region of the binary solvent systems with p-dioxane suggests a collective behaviour of the polar solvents surrounding an S, solute for the CT interaction to generate the radical ions. The observed Raman wavenumbers were compared with those of DPO in the So, S, and T, states and qualitative correlation among them is discussed.

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Photoionization of diphenylhexatriene and diphenylbutadiene ion radicals in various polar solvents by using time-resolved resonance CARS

Cited by 11 publications

References 0 publications

Distortion of the Fluorescence Spectrum of all-trans-1,6-Diphenyl-1,3,5-hexatriene with Increasing Laser Pulse Excitation Energies

Distortion of the Fluorescence Spectrum of all-trans-1,6-Diphenyl-1,3,5-hexatriene with Increasing Laser Pulse Excitation Energies

Experimental and theoretical coherent anti-Stokes Raman scattering studies on triplet excited anthracene

Transient resonance coherent stokes Raman scattering spectra of photoinduced radical ions of diphenyloctatetraene in polar solvents

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