The difference in the contact potential measured before and after {HEAD ~ heating} provides an indication of {TAIL ~ the mobile ion concentration} in the oxide layer 
The difference in the contact potential measured before and after { HEAD ~ heating } provides an indication of { TAIL ~ the mobile ion concentration } in the oxide layer
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH