{HEAD ~ sputter} etching {TAIL ~ the surface} of said substrate with energetic gas ions to remove traces of residual hydrocarbon and to preferentially reduce the concentration of alkali metal atoms and alkali metal oxides at the substrate surface 
etching
{ HEAD ~ sputter } etching { TAIL ~ the surface } of said substrate with energetic gas ions to remove traces of residual hydrocarbon and to preferentially reduce the concentration of alkali metal atoms and alkali metal oxides at the substrate surface
HEAD HEAD HEAD HEAD HEAD 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH