Berlin 2001 – scientific programme
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A: Atomphysik
A 17: Posters Friday (Spectroscopy)
A 17.28: Poster
Friday, April 6, 2001, 12:30–15:00, AT3
Resonant multicolour spectroscopy in the Ca− photodetachment continuum — •Victor V. Petrunin, Michael Harbst, and Torkild Andersen — Institute of Physics and Astronomy, University of Aarhus, Denmark
Doubly excited states with the same parity as the ground state of a negative atomic ion have been difficult to study by photon absorption techniques since more photons should be absorbed than required to liberate an electron. We report the observation of the predicted metastable 4p3 4S state in the negative calcium ion, utilizing a new spectroscopic technique based on non-linear resonant multicolour absorption via the autodetaching 4s4p2 4P state. The excitation of the quartet S state is monitored by state-selective photoionization of Ca atoms, produced exclusively via autodetachment of the quartet S state. The binding energy of the Ca− (4p3 4S) ion is determined to be 586.86(10) meV with respect to the parent Ca(4p2 3P) state, a value less than 3 meV from the binding energy predicted by van der Hart in 1999. The lifetime of the quartet S state is determined to be larger than 7 ps.