PHOTOION SPECTROSCOPY OF ATOMIC HO, ER AND TM IN THE REGION OF THE 4DGIANT-RESONANCES

Using synchrotron radiation in combination with atomic beam and time-o f-flight technique, the partial ion yield spectra sigma(X(n+)) of Ho, Er and Tm in the region between 130-200 eV were measured. The signals are dominated by Fano-type resonances of singly charged photoions sigm a(X(+)) which can be attributed to discrete transitions X 4d(10)4f(n)- ->X4d(9)4f(n+1) followed by the autoionization process X 4d(9)4f(n+1)- ->t X(+) 4d(10)4f(n-1)+epsilon d,g. This interpretation is corroborate d by ab initio Hartree-Fock calculations of the resonant photoabsorpti on cross section.