Bridging-Halogen Dependence of Ultrafast Dynamics of Excitons in Quasi-One-Dimensional Platinum Complexes

Ultrafast dynamics of lattice relaxation of excitons in quasi-one-dimensional halogen-bridged platinum complexes

“…As indicated by an arrow at 1.1 eV, the oscillation is followed by the slow decay with a lifetime of about 5.5 ps. 10 At 0.9 and 1.0 eV, the oscillation lasts at least for five periods. To reproduce this fact in the calculation, the second Gaussian component of the narrower frequency width W 2 is included in JЈ().…”

“…10 In the experiment, the samples of Pt-Br at room temperature are excited at 1.6 eV. This photon energy corresponds to the low-energy tail of the CT absorption band.…”

“…The lifetime of STE is determined from the luminescence decay (5.5 Ϯ1 ps). 10 To reduce the degree of freedom in JЈ(), we have to assume a specific function shape appropriately. We have tried several types of JЈ(), and have found the following form which consists of two Gaussian components with the same center of gravity is appropriate.…”

“…It is reproduced by a model calculation based on wave packet propagation on an interaction mode composed of frequencydispersed bulk phonons. This model is also applied to the previous results in Pt-Br, 10 and for both the systems, the frequency spectra of phonons which compose the interaction mode have been estimated. Meanwhile, the annihilation dynamics of the STE is investigated by observing the decay of the luminescence.…”

Observation of the wave-packet oscillation during the exciton self-trapping process in a quasi-one-dimensional halogen-bridged Pt complex

“…The self-trapped exciton ͑STE͒ luminescence of the Pt complexes generally shows hot luminescence from vibrationally excited states in the high-and low-energy tails of the luminescence band. 8,9 The present authors recently showed that the vibrational relaxation of hot STE's occurs with the time constant of about 500 fs in one of the Pt complexes, ͓Pt͑en͒ 2 ͔͓Pt͑en͒ 2 Cl 2 ͔(ClO 4 ) 4 (X Ϫ ϭCl Ϫ , en ϭethylenediamine, hereafter we abbreviate as PtCl͒ using femtosecond time-resolved luminescence spectroscopy. 10 If we excite the free excitons by the optical pulse, whose duration is shorter than the vibration period, and the excitons preserve coherence during the immediate self-trapping process, we can expect the formation of a wave packet and its oscillation, which can be observed as an oscillation in luminescence intensity.…”