POPULATION OF SPUTTERED METASTABLE SILVER ATOMS

Neutral atoms released by ion induced sputtering of polycrystalline si lver were investigated by resonant laser post-ionization and time-of-f light mass spectrometry. Two different resonant ionization schemes wer e employed to detect Ag atoms emitted either in the first metastable e lectronically excited state (4d(9)5s(2) D-2(5/2), excitation energy 3. 75 eV) or in the ground state. From the saturation behavior of the pho toionization process, the relative population of the metastable state with respect to the ground state was determined. A surprisingly high p opulation of several percent is found which is interpreted in terms of the screening model.