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