Preliminary experiments on the photoelectric detection of Raman spectra are described making use of commonly available spectroscopic equipment in conjunction with the new RCA-931 photomultiplier tube. A more eleborate experiment is described using a large planegrating monochromator as the dispersing device. The photoelectric current was suitably amplified and continuously recorded making use of a galvanometer and photographic galvanometer deflection recorder. The limit of detection set by the thermionic emission at room temperature of the photomultiplier has been reached. It is shown that the minimum intensity observable photoelectrically compares favorably with the minimum commonly observed photographically in Raman spectra. A rough order of magnitude experiment was performed with the photomultiplier to ascertain the feasibility of the photoelectric method for measuring intensities in arc and spark spectra under high dispersion. An arrangement of apparatus for quantitative spectroscopic analysis photoelectrically is suggested.
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