Two-step resonant photoionization spectroscopy of CoI and NiI: continuum structure near the first ionization limit

We explored the continuum structure of Co I and Ni I near the first ionizat ion limit using one-color and two-color two-step photoionization spectrosco py. The ionization spectra of both elements show a large number of autoioni zing features, The use of different excitation schemes involving intermedia te states with different angular momentum allowed the assignment of the ang ular momentum for part of the detected autoionizing states. Several of thes e states could be identified as members of different Rydberg series. (C) 19 99 Elsevier Science B.V. All rights reserved.