{TAIL ~ A solid material} or combination of {HEAD ~ materials} is evaporated in the chamber to form vapor 
{ TAIL ~ A solid material } or combination of { HEAD ~ materials } is evaporated in the chamber to form vapor
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH