Plan apo tirf 100

Figure S3 sketches the optical setup. We used a continuous-wave laser diode (frequency-doubled Nd:YAG) with an emission wavelength of 532 nm to illuminate the sample via a beam splitter (ratio, 50:50) and a high numerical aperture (NA) objective (Plan APO TIRF 100×, NA 1.45, Nikon). The AFM (Bioscope, Bruker) is mounted on a customized stage on top of the sample holder stage. A 720-nm low-pass (LP) filter is used to filter the fluorescence light and to suppress the light of the broad AFM deflection laser (685 nm). To further reduce any residual light of the excitation laser, we used an additional 540-nm LP filter. The fluorescence light passes a beam splitter (ratio, 90:10), in which 90% of the transmitted light is focused via a lens (f = 300 mm) on the entrance slit of a spectrometer (Acton SpectraPro 2300i, 300 lines/mm), where it is detected by a Peltier-cooled charge-coupled device camera (Andor DU401A BR-DD). The remaining 10% of the light is directed to a polarizing beam splitter, resulting into two orthogonally polarized beam paths, which are detected individually by two single-photon counting modules (SPCM-AQR, Perkin and Elmer). Exchanging the polarizing beam splitter with a nonpolarizing beam splitter allows us to perform Hanbury-Brown and Twiss autocorrelation measurements.