Extended Data Figure 3: Chemical specificity comparison between epr-SRS and fluorescence imaging.

a, On-resonance epr-SRS imaging of Alexa647-labelled EdU in HeLa cells at 1,606 cm−1 (λpump = 909 nm). b, Off-resonance image at 1,580 cm−1 (λpump = 911 nm) of the HeLa cells in a. c, d, Two-photon fluorescence images of the HeLa cells in a at 810 nm (c) and 812 nm (d) around the two-photon excitation peak of Alexa647. e, Absorption (solid) and emission (dashed) spectra for CF640R (green), Alexa647 (blue), DyLight650 (magenta), Cy5.5 (red), ATTO700 (cyan) and ATTO740 (yellow). Scale bars, 10 μm.