High-resolution projectile Auger spectroscopy for Li, Be, B and C excited in single gas collisions. I. Line energies for prompt decays

The ejected-electron spectra of highly excited autoionising levels of Li, Be, B and C have been studied by using the projectile electron spectroscopy method. Singly and doubly core-excited states are strongly populated in 100 to 500 keV Li + , Be + , B + and C + single collisions with He and CH 4 . High resolution is obtained by selecting a small observation angle (6.4 degrees ) with respect to the beam axis. Numerous states, previously not seen, have been resolved and identified by comparison with existing theoretical data. For a large number of core-excited states, absolute Auger transition and excitation energies are given. In particular, isoelectronic sequences for singly core-excited lithium-like (Z=2-16) and doubly core-excited helium-like (Z=1-14) autoionising states are studied.