Highly charged ions in field evaporating 4d-transition metals

An energy-focused time-of-flight atom-probe has been employed in a search for high ionic charges obtained in field-evaporating Zr, Nb, Mo, Rh, Pd and Ag, the 4d-transition metals. Although no new higher charges than the already established ones are found for these metals the maximum abundance of the highest charge is determined in each case. An empirical rule predicting the limits of the charge of field-evaporating ions is proposed.