sputtering of a number of different materials $($zinc$,$ copper, aluminium, silicon and titanium$)$ by argon ions.

Fig. Q$2.$

i$)$ Define the term sputter yield in terms of particle fluxes

ii$)$ Why do the sputter yields start to decrease at very high ion energy?

iii$)$ At $1000eV$ bombarding energy why is the sputter yield of zinc much higher than that of titanium?

iv$)$ What is the sputter yield of titanium

when the bombarding argon ion velocity is $6\mathrm{.}95{10}^{4}m{s}^{-1}?$

Can you answer mainly part iii and iv please