Fluorescent emission generally occurs in {HEAD ~ a time frame} of {TAIL ~ less than 10 nanoseconds} 
of
Fluorescent emission generally occurs in { HEAD ~ a time frame } of { TAIL ~ less than 10 nanoseconds }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL