4He irradiation of zircon, ZrSiO4, using a micro-patterned, Si-based energy filter

Abstract The quantitative evaluation of alpha-particle damage in the mineral zircon, ZrSiO 4 , using 4 He irradiation experiments is difficult because the vast majority of atomic knock-ons in the target are concentrated in a narrow depth range near the ends of the He-ion trajectories. Here we present a new concept to overcome this problem, namely, tailoring the depth profile of damage by means of a micromechanically fabricated “energy filter”. Lamellae of 1.5 μm thickness, prepared from ZrSiO 4 using the focused-ion-beam technique, were subjected to irradiation with 8.8 MeV 4 He ions. Five irradiations with ion fluences in the range 2.5 × 10 15 –1 × 10 17  cm −2 have resulted in mild to severe damage, as monitored by the broadening and downshift of SiO 4 -stretching Raman bands. Our results may provide a means for quantifying the contribution of alpha particles to the total self-irradiation damage in zircon.