Pressure effects on CO2-laser coincidences with ethene and ammonia investigated by photoacoustic detection

Carbon dioxide laser coincidences were investigated by photoacoustic detection at laser lines 10P(28) and 9P(28) with ethene and at 10P(20) and 10P(16) with ammonia. The intensities of coincidences were measured as a function of pressure of a buffer gas (dry air) and pure gas. The intensities of two ammonia coincidences show an inversion with pressure. A method of eliminating all pressure effects other than those of spectral nature from the PA signal was introduced. This enabled deriving the pressure broadening coefficients of the coinciding absorption lines. (C) 1998 Published by Elsevier Science B.V