Fig. 1

SREF microscopy. a Energy diagram for SREF process. b Microscope setup for SREF imaging. c SREF spectrum of 5-μM Rh800 in DMSO. SREF spectrum (solid line) is fitted with a sum of Voigt shape with an exponential decay background (dashed line). d Normalized SREF peak as Voigt shape (solid line) and Lorentzian shape after laser broadening deconvolution (dashed line)