Constitution of Phosphorous Acid and the Phosphites

Abstract

MENZIES¹ and Bär² showed that it is possible to obtain Raman spectra with crystal powders in which at least some of the stronger lines of the substances are recorded. I have shown³ that the technique of obtaining the spectra with powders is vastly improved if a pair of complementary filters is used, one having a sharp cut-off on the longer wave-length side between the source and the scattering substance to isolate a definite exciting line from the exciting source of light, and the other having a sharp cut-off to the shorter wave-length side in the path of the scattered light in order selectively to weaken or absorb the exciting wave-length. Using this device, it is now possible to record the faintest lines and bands in the spectra of crystal powders and even of amorphous solids by giving suitably long exposures.