In {HEAD ~ addition}, the measuring chamber is provided with {TAIL ~ a pressure sensor} for detecting a photoacoustic signal generated in the measuring chamber 
In { HEAD ~ addition } , the measuring chamber is provided with { TAIL ~ a pressure sensor } for detecting a photoacoustic signal generated in the measuring chamber
OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH