Feature

Laser Depletion Spectroscopy

S. E. Harris

To perform depletion spectroscopy, a radiating core-excited level is used as a reference level from which to access the autoionizing manifold, as illustrated in the figure. The radiating level is impulsively excited, and a detector monitors the resulting fluorescence from this level. A tunable dye laser is passed through the excited vapor to transfer the fluorescing atoms to other core-excited levels nearby. As the laser is scanned in frequency, a level is encountered, and the excited population is transferred to it, resulting in a depletion in the amount of fluorescence observed from the reference level. The location of the depletion signal, as a function of dye laser frequency, determines the energy of the accessed level, relative to the reference level. The shape of the depleted signal, as a function of laser intensity, can be analyzed to determine the oscillator strength and Lorentz width of the transition.