Electron affinities of six bound states of Ce- formed by attachment of 6p and 5d electrons to Ce

High-resolution laser spectroscopy on the negative osmium ion

We have applied a combination of laser excitation and electric-field detachment to negative atomic ions for the first time, resulting in an enhancement of the excited-state detection efficiency for spectroscopy by at least 2 orders of magnitude. Applying the new method, a measurement of the bound-bound electric-dipole transition frequency in (192)Os- was performed using collinear spectroscopy with a narrow-bandwidth cw laser. The transition frequency was found to be 257.831 190(35) THz [wavelength 1162.747 06(16) nm, wave number 8600.3227(12) cm(-1)], in agreement with the only prior measurement, but with more than 100-fold higher precision.

Measurement of the electron affinity of cerium

The electron affinity of cerium has been measured using laser photodetachment electron spectroscopy. The electron affinity of Ce(1G4) was determined to be 0.955 +/- 0.026 eV. The data also show that Ce- has at least two bound excited states with binding energies of 0.921 +/- 0.025 eV and 0.819 +/- 0.027 eV relative to the (1G4) ground state of the cerium atom. The present experimental measurements are compared to recent calculations of the energy levels of Ce-. Strong disagreement with the most recent theoretical atomic structure calculations highlights the complicated nature of this particular lanthanide.

Experimental studies of Os(-): observation of a bound-bound electric dipole transition in an atomic negative ion

The first experimental studies of Os(-) reveal the presence of two very strong resonances. One state is a narrow shape resonance lying only 3.52(12) meV above the ground state detachment threshold, while the other is bound by 11.48(12) meV. Convincing evidence that these states have odd parity is presented, making Os(-) the only known atomic negative ion with bound states of opposite parity. Additionally, the binding energies for the Os(-) ground state ((4)F(e)(9/2)) and first excited state ((4)F(e)(7/2)) are measured to be 1.077 80(12) eV and 0.553(3) eV, respectively.