The common hydrocarbon gases and vapors within cell highly absorb the infrared energy emitted by {HEAD ~ laser} thereby producing {TAIL ~ an acoustic disturbance} which is detected by a transducer which produces an electrical output signal proportional to the concentration of the hydrocarbon gases and vapors 
producing
The common hydrocarbon gases and vapors within cell highly absorb the infrared energy emitted by { HEAD ~ laser } thereby producing { TAIL ~ an acoustic disturbance } which is detected by a transducer which produces an electrical output signal proportional to the concentration of the hydrocarbon gases and vapors
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH