{HEAD ~ Electrons} are caused to bombard {TAIL ~ the surface} of the solid material, transferring their energy to the atoms/molecules comprising the source material and resulting in sublimation 
are caused to bombard
{ HEAD ~ Electrons } are caused to bombard { TAIL ~ the surface } of the solid material , transferring their energy to the atoms / molecules comprising the source material and resulting in sublimation
HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH