Fluorescence images of 10×10-μm2 sample regions recorded for Cy5 spin-cast on a SIF a and on a glass coverslip b at the subnanomolar concentration. c An as-prepared SIF in the absence of Cy5. Intensity scale unit: cps. Images were recorded by raster scanning the sample over a time-resolved confocal microscopy (MicroTime 200, PicoQuant). A single mode pulsed laser diode (635 nm, 100 ps, 40 MHz) (PDL800, PicoQuant) was used as the excitation light. An oil immersion objective (Olympus, 100×, 1.3 NA) was used.