First, if the VO2 layer is rough, an effective mixing of the VO2 with {HEAD ~ air} over {TAIL ~ a certain depth} is obtained 
over
First , if the VO2 layer is rough , an effective mixing of the VO2 with { HEAD ~ air } over { TAIL ~ a certain depth } is obtained
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH