RECENT EXPERIMENTAL ACHIEVEMENTS WITH NEGATIVE-IONS

Experimental results obtained about the atomic physics of negative ions since the Physica Scripta 1991 review are presented. Most new data concern the metastable states and resonances of He- and alkaline-earth negative ions, and the ions of the C- column. A few photodetachment experiments were also performed on ions submitted to external fields, and we have now a better understanding of the response of negative ions to microwaves and ponderomotive threshold shifting. A great progress was made in the study of multiphoton detachment processes; 1991 was the year of discovery of excess-photon detachment. Every year brings new precision detachment threshold measurements about, but still relying on the 1985 measurement numerical reasons make it necessary to revise the electron affinity of oxygen: EA(O) = 11 784.648(6) cm(-1), or 1.4 611 107(17) eV.