Solvent/Solute Interactions Probed by Picosecond Transient Raman Spectroscopy: Vibrational Dynamics and State Ordering in S1 1,4-Diphenyl-1,3-Butadiene

Abstract

We present the SI Raman spectra of 1,4-diphenyl-1,3-butadiene (DPB) in n-hexane and THF at three different probe wavelengths. We assign the Raman spectra of S1 DPB on the basis of gas-phase and low-temperature fluorescence spectra. Bands assignable to the llB, and 2lA, states from the gas-phase spectra are both present in solution. These results suggest that the state we are observing in solution is a mixed state, having both llB, and 2lA, character. Broad vibrational bands associated with the olefin region of DPB suggest that there is a distribution of s-trans conformers in SI DPB. We also observe mode-specific, solvent-dependent dynamics in the excited-state Raman spectra. In particular, the peak position and bandwidth of the mode associated with the C=C phenyl stretch change as the delay is increased. We suggest that the mode-specific dynamics are related primarily to vibrational relaxation in SI DPB.

The Photophysics and Dynamics of Diphenylbutadiene in Alkane and Perfluoroalkane Solvents

“…It seems reasonable to ascribe this fast component to vibrational or perhaps torsional relaxation. 33,34 ) Uncertainties in the measured time constants are estimated to be (5%. Radiative and nonradiative rates were determined from the observed time constants of these decays τ fl and the emission quantum yields via the relations k rad ) Φ fl /τ fl and k nr ) τ fl -1k rad .…”

“…[24][25][26][27][28] Many workers have also addressed the nature of the excited-states of DPB in relation to the other members of the diphenylpolyene series. [29][30][31][32][33][34][35] A valuable overview of much of this work prior to 1990 was provided in the thorough review by Saltiel and Sun. 36 Although a great deal is known from prior research, some nontrivial questions about the photophysics of DPB remain.…”

Picosecond Time-Resolved Fourier-Transform Raman Spectroscopy and Normal-Mode Analysis of the Ground State and Singlet Excited State of Anthracene

“…These considerations have led to efforts to implement time-resolved resonance Raman spectroscopy to probe excited states. [1][2][3] However, this approach has been limited to samples that are characterized either by low fluorescence quantum yields or by a wide spectral separation between fluorescence and the resonance Raman scattering. To broaden the applicability of this approach, we have recently developed the technique of picosecond time-resolved Fouriertransform (FT) Raman spectroscopy.…”

“…Third, the lowest lying excited state may be only weakly allowed and masked by a nearby strongly allowed transition. These considerations have led to efforts to implement time-resolved resonance Raman spectroscopy to probe excited states. − However, this approach has been limited to samples that are characterized either by low fluorescence quantum yields or by a wide spectral separation between fluorescence and the resonance Raman scattering. To broaden the applicability of this approach, we have recently developed the technique of picosecond time-resolved Fourier-transform (FT) Raman spectroscopy. , This method takes advantage of the development of FT Raman spectroscopy, which utilizes Raman excitation in the near-infrared region and interferometric detection of the Raman scattering.…”

Intramolecularcharge transfer in donor‐bridge‐acceptor compounds with paired linearly conjugated or cross‐conjugated pathways

“…have previously determined that the thiophene rings are twisted 42° from the plane of the molecule in the ground state in the macrocycles based on density functional theory calculations . Photoexcitation has been shown to cause a flattening of linearly conjugated molecules in the excited state and results in a picosecond time constant …”