Constitution of Phosphorous Acid and the Phosphites


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.


  1. 1

    A. C. Menzies, NATURE, 124, 511 (1929).

  2. 2

    R. Bär, NATURE, 124, 692 (1929).

  3. 3

    R. Ananthakrishnan, Current Science, 5, 131 (1936).

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ANANTHAKRISHNAN, R. Constitution of Phosphorous Acid and the Phosphites. Nature 138, 803 (1936).

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