Single- and multiphoton detachment of K

Single- and multiphoton detachment rates have been calculated for K − using the R -matrix Floquet approach. Single-photon detachment rates, obtained at a laser field peak intensity of 10 9 W cm −2 , are discussed and compared with other theoretical work. Two-photon detachment rates at the same intensity have also been obtained, and similarities with results from earlier calculations for Li − and Na − are discussed. Three-photon rates are also presented at this laser intensity, and are compared and contrasted with those arising in the single-photon case, since both involve resonance structure with 1 P o symmetry. The influence of resonances such as the 5s 2 1 S e doubly excited state and excitations of the residual atom are also considered.