Measurements of absolute photoionization cross sections of the excited 7d and 8d states of cesium

We have carried out measurements of absolute photoionization cross sections of the excited nd²D_3/2,5/2 states of cesium for principal quantum number n=7 and 8. Absolute cross sections have been determined experimentally using the technique of measuring depletion in the fluorescence signal from the excited states of atoms due to photoionization. The measurement was made with a linearly polarized ionization laser light at 532-nm wavelength. Photoionization cross sections have been determined as (3.5±1.4)×10^-18 cm² and (3.1±1.2)×10^-18 cm² for the 7d²D_3/2 and 7d²D_5/2 states, and (2.4±1.0)×10^-18 cm² and (1.6±0.6)×10^-18 cm² for the 8d²D_3/2 and 8d²D_5/2 states, respectively. We also propose an alternative method to measure the absolute cross sections for photoionization from highly excited Rydberg states, which is based on the methodology of the fluorescence depletion technique.