Femtosecond nonlinear optical dynamics of excitons in J-aggregates

The dynamics of one-dimensional excitons in liquids

“…In addition, the excited state population of one-excitons gives rise to absorption on the one-to two-exciton transitions. This was only recently demonstrated by Fidder et al 39 and by Minoshima et al 40 for PIC aggregates, and by Johnson et al 41 for BIC aggregates. The absorption is somewhat blue-shifted compared to the bleach, which, as we will demonstrate, can be employed to determine the delocalization length of the excitons.…”

“…3͑b͒ is shown how the pump-probe signal rapidly decreases when very small delays are introduced between the pump-and probe-pulses, while for larger delays hardly any change seems to occur at all. The fast decrease of the signal does not represent ultrafast dynamics, such as has been suggested by Minoshima et al 40 for PIC-aggregates at low temperature and Gagel et al 43 for PIC aggregates at room temperature, since the decrease follows the pulse envelope. Instead, the additional signal around zero-delay is due to coherent coupling between both optical beams.…”

“…Also, multiexponential decay is often observed, 31,40,43 which can in principle be explained in terms of a distribution of exciton delocalization lengths in the sample. 13 However, the decay times of the multiexponent may differ considerably, 31,40,43 which suggests that fundamentally different states contribute to the observed decay. We present here results on the population decay of TDBC in water, and interpret these in a simple kinetic model, based on population dynamics among the various exciton bands.…”

Intrinsic optical bistability of thin films of linear molecular aggregates: The one-exciton approximation

“…For these species, typically, ␥ 0 Ϸ 1/3 ns −1 and Ϸ 600 nm. [47][48][49][50][51][52] With this in mind and choosing L = /2 ͑or kL =1͒, we obtain the following estimate: ⌫ R Ϸ 10 −18 n 0 cm 3 ps −1 . This value for L is easily accessible with the spin-coating method 42 and guarantees the applicability of the mean-field approach for the description of the thin film optical response.…”

Photon emission statistics and photon tracking in single-molecule spectroscopy of molecular aggregates: Dimers and trimers

“…Optical spectroscopy offers a large tool box to study this interplay. The vast majority of optical spectroscopies applied to these complex systems consist of bulk measurements, where since the late 1980s in particular nonlinear optical techniques, such as photon echoes, [10][11][12][13] pump-probe, [14][15][16][17] and, most recently, two-dimensional correlation spectroscopy, 8,[18][19][20][21][22] have opened new ways to unravel details hidden in linear spectroscopy. In parallel to these developments, also single-molecule spectroscopy (SMS), introduced around 1990, 23,24 has proven a powerful experimental technique to study complex moleca) Electronic mail: j.knoester@rug.nl.…”