Measurement of the electron affinity of potassium - art. no. 022503

A high-resolution measurement of the electron affinity of potassium has bee n made using the laser photo-detachment threshold technique. A sensitive co llinear laser-negative-ion beam apparatus was used in the experiment. We in vestigated the threshold for photodetachment of K- leading to the formation of residual K atoms in the 4p(3/2) state. These excited atoms were selecti vely detected by use of resonance ionization. The result, an electron affin ity of 501.459(12) meV for K, is significantly more accurate than previous measurements and current theory.