Line Reflection Spectra of Solids

Abstract

A new interpretation of reflection spectra in solids, particularly Sm${\mathrm{Cl}}_2$·6${\mathrm{H}}_2$O, is offered. The appearance of new absorption lines and the strengthening of others in the spectrum of a conglomerate as compared with that of a single crystal is explained as being caused by an increased path length travelled by the light through the crystal rather than by surface atoms as heretofore considered. This increased path results from the high refractive index for the light of wave-length of the absorption lines, which makes it difficult for such a ray, once it has entered a small crystal fragment, to leave. A new phenomenon of reversal of lines from absorption in a single crystal to emission in a conglomerate is described for a multiplet of the Gd${\mathrm{Cl}}_2$·6${\mathrm{H}}_2$O spectrum.