Momenta of the particles emitted by a target heavily irradiated with low-energy ions

The total momenta of the particles emitted by a target intensely sputtered with heavy noble-gas ions with an energy of E ₀≈0.5 keV are measured. For liquid Ga targets and Ga targets at the premelting temperature, the measured momenta are close to the expected values for the sputtered metal atoms and reflected ions, whereas for Cu and Zr targets, the measured momenta are significantly higher. It is assumed that these excessive momenta are related to the sputtering of the noble gas atoms implanted into the target. The average energy of these atoms is estimated as 〈E〉≈20 eV. When gallium is irradiated, the implanted atoms diffuse predominantly to the surface and then are desorbed.