ABSOLUTE DENSITY-MEASUREMENTS OF AMMONIA SYNTHESIZED IN N-2-H-2 MIXTURE DISCHARGES

Measurements of absolute density of ammonia in nitrogen-hydrogen mixtu re de glow discharges were performed by employing photofragment transl ational spectroscopy associated with laser induced fluorescence (LIF) of the H ground state atoms. The dissociation energy of ammonia using the photolysis at 205 nm was determined to be (4.34+/-0.07) eV. The H atom LIF measurements were calibrated by vacuum ultraviolet absorption spectroscopy on the Lyman-alpha (121 nm) line. The ammonia synthesize d in the discharge has a maximum density of about 8X10(12) cm(-3) for a 75% H-2-25% N-2 mixture, a discharge current of 50 mA and a pressure of 2 Torr. (C) 1996 American Institute of Physics.