Selected recent multiphoton experiments with negative ions

This paper presents selected recent multi-photon experiments on a variety of atomic negative ion species. Two-photon detachment spectroscopy has been conducted on the Ir^- [5d⁸6s^{2 3}F4] and Pt^- [5d⁹6s^{2 2}D5/2] ions via magnetic dipole transitions in a 1 + 1 photon absorption scheme. Sharp resonances in the photodetachment yields are observed in the two cases as a result of M1 transitions via J = 4 - 3 and J = 5/2 - 3/2, in Ir^- and Pt^-, respectively. Probing electric-dipole-forbidden transitions are new to the study of negative ions, and in the present case, the fine structure determinations have been improved by over three orders of magnitude.