In contrast, {HEAD ~ LIF detection} suffers from {TAIL ~ the exited molecules} emitting in many frequencies and directions 
suffers from
In contrast , { HEAD ~ LIF detection } suffers from { TAIL ~ the exited molecules } emitting in many frequencies and directions
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH