The ΔV=2 CO laser: Photoacoustic trace gas detection

In order to improve the detection limit of biologically interesting gas, a ΔV=2 CO laser operating between 2.8 and 3.8 μm is developed; 165 laser lines divided over 24 bands have been observed with maximum intracavity power of 11 Watt. The fingerprints of ethane, pentane and ethylene have been measured in a dilute mixture using nitrogen as buffer gas. The detection limits of C2H4, C2H6, C5H12 in N2 are 2 ppb, 0.4 ppb and 0.5 ppb, respectively (S/N=1).