Two-Photon Detachment of Negative Ions via Magnetic Dipole Transitions

Two-photon detachment spectroscopy of the Ir- (5d86s2 3F4) and Pt- (5d96s2 2D5/2) ions is conducted using laser intensities ∼1010 W/cm2. Sharp resonances in the two-photon detachment yields, attributed to magnetic dipole transitions, are observed at photon energies of 7087.3±0.4 and 9740.9±0.5 cm-1 for Ir- and Pt-, respectively. Multiconfiguration Dirac-Fock calculations predict fine structure splittings of 6671 and 9535 cm-1 for Ir- (J=4-3) and Pt- (J=5/2-3/2), and A coefficients of 7 and 14 s-1, respectively, for the upper fine structure levels of the ions.