The 6s-6d quadrupole resonances in two-photon ionisation of caesium. Measurement of ion asymmetry and spin polarisation

In the two-photon ionisation of Cs atoms resonances may be expected which correspond to a quadrupole 6s-nd transition associated with the first photon. At the 6D 5/2 and 6D 3/2 resonances the ratio of photoionisation cross sections for circularly polarised and for linearly polarised light (ion asymmetry) and the spin polarisation of the photoelectrons ejected by circularly polarised light have been measured. The ratios of the radial transition matrix elements from the 6D to the epsilon P and epsilon F continuum states were derived from the experimental results.