The excitation spectrum and emission spectra (bold line) are shown for
Fluorescein (FITC). The red-shaded region represents the bandpass filter
commonly used to measure FITC fluorescence. On most flow cytometers, FITC
is excited by an argon laser (tuned to 488 nm)
Compare the FITC fluorescence spectra to spectra for several FACS immunofluorescence dyes.