Single and multiphoton detachment of Na-

Single and multiphoton detachment rates have been calculated for Na- using the R-matrix Floquet approach. In the low-intensity limit the results are i n agreement with other recent calculations of the total photodetachment cro ss section. At intensities of 10(10) W cm(-2) two-photon detachment rates a re presented and similarities with earlier calculations in Li- are discusse d. Three-photon rates are also presented at this intensity and are compared and contrasted with the single-photon case since both involve resonance st ructure with P-1(o) symmetry. The influence of resonances such as the 4s(2) S-1(e) doubly excited state and excitations of the residual atom are also considered.