PRESSURE EFFECTS ON CO2-LASER COINCIDENCES WITH ETHENE AND AMMONIA INVESTIGATED BY PHOTOACOUSTIC DETECTION

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