Experimental determination of the cross-sections for neutral Bremsstrahlung: II. High temperature air species—O, N and N 2

Abstract

The low energy cross sections for neutral Bremsstrahlung for the major species of high temperature Air—O, N, and N 2 have been measured. The experiments were performed behind reflected shocks by measuring the absolute, infrared intensity of appropriate shock heated gas mixtures. The radiation was directed with a rapid scanning infrared spectrometer covering a total spectral range of 2·0–5·4μ. The data were analyzed by assuming that the observed continuum was due to free-free scattering of electrons from the neutral species in the gas studied. The neutral Bremsstrahlung cross section was determined for (1) atomic oxygen in O 2-Ne mixtures, (2) atomic nitrogen in N 2-Ne mixtures, and (3) for molecular nitrogen from data on pure N 2. Further checks on the experimental values were obtained by comparing the measured cross sections against intensity data from air and N 2-Ar and N 2-Ne mixtures. The data were analyzed for the “effective nuclear charge squared” and radiation absorption cross section of the active species. The data are compared with previous experimental measurements and with theoretical calculations.