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