Saturation effects in resonant three-photon ionisation of sodium with a non-monochromatic field

Presents an experimental and theoretical analysis of two-photon-resonant three-photon ionisation of Na. The transition 3S to to 4D to e- is studied. The theoretical analysis takes into account saturation effects, the finite laser bandwidth and the expansion of the active interaction volume with laser intensity. Good agreement is obtained between theory and experiment.