RESONANCE-ABSORPTION MEASUREMENTS OF ATOM CONCENTRATIONS IN REACTING GAS-MIXTURES .2. 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-á 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). © 1979 American Institute of Physics.