On the mechanisms of formation of excited yttrium atoms under ion bombardment of yttrium and yttrium-aluminum garnet

A comparison of the emission spectra of excited yttrium atoms ejected from the surface of the metal yttrium and yttrium-aluminum garnet (YAG) by Ar+ ions with energy 20 keV to the emission spectra of excited yttrium atoms ejected from the surface of metal yttrium by Xe+ ions with energy 40 keV has been made. A sharp increase of population states of yttrium atoms with low energy excitation (z2D°, z4F°) ejected both from metallic yttrium and YAG under Ar+ bombardment was established when compared with the metallic yttrium bombarded Xe+ ions. The spatial distribution of radiation of excited yttrium atoms ejected from yttrium and YAG by Ar+ ions was measured. It showed that the yttrium atoms in the excited states z2G° and z4F° have low kinetic energy (order eV), whereas the yttrium atoms in other states have kinetic energy of order 100–300 eV and also more than 4 keV. It was proposed that, in addition to formation by a collision mechanism, there are low excited yttrium atoms due the break-up of yttrium oxide molecules in unstable electron states of excited yttrium and oxygen atoms.