2-PHOTON DETACHMENT OF NEGATIVE-IONS VIA MAGNETIC DIPOLE TRANSITIONS

Two-photon detachment spectroscopy of the Ir- (5d(8)6s(2 3)F(4)) and P t- (5d(9)6s(2 2)D(5/2)) ions is conducted using laser intensities simi lar to 10(10) W/cm(2). Sharp resonances in the two-photon detachment y ields, attributed to magnetic dipole transitions, are observed at phot on energies of 7087.3 +/- 0.4 and 9740.9 +/- 0.5 cm(-1) for Ir- and Pt -, respectively. Multiconfiguration Dirac-Fock calculations predict fi ne 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.