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