Low cost solar array project: composition measurements by analytical photon catalysts. Third quarterly report, April 1-June 30, 1979

Abstract

The object of this research is to assess the applicability of the photon catalysis technique for effecting composition analysis of silicon samples. In particular, the technique is to be evaluated as a detector for the impurities Al, Cr, Fe, Mn, Ti, V, Mo, and Zr. During the first reporting period Al, Cr, Fe, and Mn were detected with the photon catalysis method. The best fluorescence lines to monitor were established and initial sensitivities to each of these elements were determined by atomic absorption calibration. In the course of these tests vapor pressure curves for these four pure substances have also been mapped. During the second quarter Ti and Si were detected with the technique. The best lines to monitor were catalogued and vapor pressure curves were determined. Attempts to detect vanadium were unsuccessful due to the refractory nature of this element and the limited temperature range of the evaporator. The third quarter was devoted to the study of impurities in silicon matrices. The evaporation process was shown to be congruent; thus, spectral analysis of the vapor will yield the composition of the bulk sample. Qualitative analysis of metal impurities in silicon was demonstrated below the part per million level. Only one atomic spectral interference has been noted so far; however, it is imperative to maintain a leak tight system due to chemical and spectral interferences caused by the presence of even minute amounts of oxygen in the active nitrogen afterglow.