Fig. 3: Femtosecond transient absorption microscopy of organic nanostructures.

a Schematic of fs-TAM. A diffraction limited pump pulse (green) is focused onto the sample by a high numerical aperture microscope objective. A probe pulse (yellow) is focussed from the top onto the sample in the wide-field. The transmitted probe is collected by the objective and imaged onto a digital camera (Supplementary Methods). Comparison of the spatial extent of the signal (stack) at different time delays allows us to dynamically track changes in the population with ~10 nm precision (right hand graph). b–d fs-TAM images of PDA, PIC and PDI at selected time delays following photoexcitation. The pump pulse covers the entire (excitonic) absorption of the systems, with probing carried out at 670 nm, 600 nm and 720 nm respectively. In all images in Fig. 1e–g the scale bar is 500 nm and the dotted line indicates the radial Gaussian standard deviation (σ; numerical value bottom left) from the excitation centre of mass (red circle). Grey lines indicate the principle transport axes, along and orthogonal to the average wire direction (see Supplementary Note 6 for respective line cuts).