Characteristics of two-element (PbMg) laser generated plasma ions were
studied using a mass-spectrometer. It was found that increasing the
fraction of Mg leads to widening of the energy spectra of Pb ions by more
than a factor of two, while the intensity of Pb ions of all charge states
does not depend on the Mg fraction. This effect is explained by the
friction existing between light and heavy ions during their expansion away
from the target.