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Figure 5 | Journal of Nanobiotechnology

Figure 5

From: Single-molecule FRET of protein structure and dynamics - a primer

Figure 5

Correlation spectroscopy can be used to probe a wide range of timescales and processes. Illustration of processes that can contribute to the fluorescence correlation functions of freely diffusing molecules, with their characteristic timescales and corresponding amplitudes. Illustrated are: photon antibunching [112] in the range of the fluorescence lifetimes of the fluorophores, τ fl ; rotational diffusion with a correlation time τ rot , and interdye distance dynamics due to FRET with a reconfiguration time τ r (note that τ rot and τ r can be in a similar range, but can be distinguished by the donor-acceptor crosscorrelation (Figure 6), which shows anticorrelated behaviour in the case of distance dynamics); triplet state blinking on a timescale τ T ; and translational diffusion (Figure 4) with a diffusion time τ diff . Timescales much greater than τ diff are not accessible with freely diffusing molecules, but can be extended by taking advantage of recurrence effects [18] (i.e. molecules returning to the confocal volume) or with experiments on immobilized molecules (Figure 7).

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