Absolute density measurements of ammonia synthetized in N2–H2 mixture discharges

Abstract

Measurements of absolute density of ammonia in nitrogen–hydrogen mixture dc glow discharges were performed by employing photofragment translational 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-α (121 nm) line. The ammonia synthesized in the discharge has a maximum density of about 8×1012 cm−3 for a 75% H2–25% N2 mixture, a discharge current of 50 mA and a pressure of 2 Torr.