Resonance absorption measurements of atom concentrations in reacting gas mixtures. II. Calibration of microwave sources over a wide temperature range

A series of experiments was carried out to calibrate three different microwave discharge lamps for analysis for D or H atoms, using Lyman-α absorption. Known concentrations of D atoms were produced in a shock tube by the reaction of 0.05–4 ppm D2 with N2O in argon at 1800–3000 K. H atoms were produced by dissociation of 2,2,3,3-tetramethylbutane (10 ppm in argon) at 980–1140 K. These absorption data were compared with the absorption calculated from Lyman-α line shapes reported in an earlier paper, good agreement being found. These experiments provide a sound basis for obtaining the temperature and concentration dependence of the absorption coefficient over a wide temperature range, for H and D concentrations between 10−12 and 10−10 mole/cc (for a 7.5 cm light path).