Improved Technique for the Raman Effect

Mercury-arc excitation of Raman spectra. The unfiltered light from a mercury arc is not well suited for an analysis of Raman spectra. The confusion of interpretation which may result is illustrated in the case of benzene.Filters for use with mercury arc.---The object of a filter is two-fold: the limitation of the excitation to light of a single wave-length (if possible) and the suppression of the continuous spectrum in the region in which the Raman spectrum appears. Raman spectra of benzene excited by the mercury arc through various filters are reproduced. Suggestions concerning the proper design and manipulation of arc, filter tubes and scattering tubes are given.Helium-arc excitation of Raman spectra.---The use of the General Electric Company's hot cathode helium arc as a source for Raman spectra excitation is described. The Raman spectrum of benzene excited by this source through a nickeloxide glass filter is reproduced.