saturation spectroscopy

saturation spectroscopy

[‚sach·ə′rā·shən spek′träs·kə·pē] (spectroscopy) A branch of spectroscopy in which the intense, monochromatic beam produced by a laser is used to alter the energy-level populations of a resonant medium over a narrow range of particle velocities, giving rise to extremely narrow spectral lines that are free from Doppler broadening; used to study atomic, molecular, and nuclear structure, and to establish accurate values for fundamental physical constants.