U. V. Pedersen

Search for stable or metastable negative Yb ions

The previously reported observation of stable negative Yb ions has been reinvestigated. No evidence is found for the existence of such ions or for long-lived metastable ions. This conclusion is limited to Yb ions with binding energies larger than 3 meV.

Lifetime measurement of the metastable Be- ion using an electrostatic ion storage ring

The lifetime of the metastable Be-(2s2p2 4P3/2) ion has been measured to be 43.40±0.10 µs by means of an electrostatic heavy-ion storage ring. This value is in good agreement with the previously reported lifetime obtained using a magnetic storage ring, but more than 3% longer than the lifetime recently measured utilizing a newly constructed electrostatic ion trap.

Excess-photon absorption via autodetaching states: potential for spectroscopy beyond the isolated core excitation method

We report the observation and study of the excess-photon absorption (EPA) phenomenon in the region of short-lived autodetaching states of negative ions at low intensities . A sensitive resonant-ionization-based technique is utilized here for the first time to investigate nonlinear processes in the continuum, including detailed studies of signal response to laser power. We demonstrate that the sensitivity of the new method is sufficient to obtain actual positions and widths of the states at the limit of low intensities. Higher intensities (i.e. above ) can lead to significant displacement of the EPA signals from the autodetaching state positions and, depending on the shape of the one-photon detachment cross section, to either broadening or narrowing of the signal peaks. The amplitude of the signal at these higher intensities typically displays a sublinear dependence on laser power.