Figure 1.

Examples from a series of fluorescence images of single LH-2 assemblies. The image size is 102 × 128 pixels and the integration time per pixel was 4 ms. The excitation power was 290 nW at λ = 800 nm. The molecule labeled 1 is an A state in a. It goes to a B′ state in b and it recovers to an A′ state in c. During the scanning of this image, a B state was formed for ≈0.5 s before recovering to the A′ state. In d a P state is reached. The circle labeled 2 is one of the rare cases where a molecule suddenly appears. Probably it was bleached to a B state during the sample preparation.