Oscillatory Excitation Transfer in Dithiaanthracenophane: Quantum Beat in a Coherent Photochemical Process in Solution

Abstract

The intramolecular electronic excitation transfer in dithiaanthracenophane (DTA) in THF solution has been investigated by probing the fluorescence anisotropy decay with a femtosecond up-conversion method. In DTA, two anthracene rings are known to be stacked parallel, but with nearly orthogonal orientation. There appeared a damped oscillation of an apparent period of 1.2 ( 0.2 ps and a damping time constant of 1.0 ( 0.1 ps. It has been found that the oscillatory behavior is consistent with the recurrence motion of an excitation between two anthracene moieties, from a theoretical analysis following a manner of Wynne and Hochstrasser (Wynne, K.; Hochstrasser, R. M. J. Raman Spectrosc. 1995, 26, 561). The magnitude of the dipole-dipole energy transfer interaction is estimated to be 40 cm -1 which is in an acceptable agreement with the experimental value (29 cm -1 ) deduced from the oscillation period. In comparison with the similar case of 2,2′-binaphthyl (BN) reported by Zhu et al. (Zhu, F.; Hochstrasser, R. M. J. Chem. Phys. 1993, 98, 1042, the electronic dephasing time T 2 ′ is significantly longer in DTA (1.0 ps) than in BN (0.2 ps). The longer dephasing time in DTA can be explained as arising from a much more fixed and rigid dimeric conformation than in BN.

Coherent Control of Oscillatory Excitation Transfer in Dithia-1,5[3,3]anthracenophane by a Phase-Locked Femtosecond Pulse Pair

“…However, this assignment agrees with that concluded from the fluorescence anisotropy experiment. 5 The two peak intensities should be the same in the Fourier spectrum on the basis of the theory derived above, although the observed peak intensities are different. The reason for this discrepancy remains unclear but might be due to the inhomogeneity of the sample.…”

Theoretical characterization of excitation energy transfer in chlorosome light-harvesting antennae from green sulfur bacteria

“…Transient anisotropy decay directly probes the orientational dynamics of transition dipole moments in a system consisting of multiple chromophores and has been used in the analysis of the lifetimes of coherent energy transfer and associated quantum coherence [70][71][72][73][74][75][76]. Following Ref.…”

“…The depolarization times of 30 fs is smaller than the first component of the TA experiments. A possible reason for this is that in terms of the Bloch equation interpretation, the time components of the TA experiments will describe the population decay (T 1 ) time, while the depolarization time includes a pure dephasing time (T ′ 2 ) as well [70,72]. The incoherent EET subsequently takes places after the ultrafast process.…”

Photoisomerization around a Fulvene Double Bond: Coherent Population Transfer to the Electronic Ground State?

“…[25] Coherent excitation transfer by resonant dipole-dipole interactions was proposed to explain oscillatory time evolution of femtosecond fluorescence anisotropy in a covalently bound anthracene dimer. [26,27] EC between 1 L a and 1 L b states of naphthalene accounts for the frequency upshift of the oscillatory photoionization signal upon excitation with an increasing excess of vibrational energy. [28] Photosynthetic systems deserve special attention.…”