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Inventory no. 29272 - Former Display Label

MASS SPECTRA
1919 & 1920

Examples of mass spectra taken in 1919 and 1920 by Dr Francis William Aston (1877-1945) in the Cavendish Laboratory, University of Cambridge, using his first mass spectrograph. The mass spectrograph, like Moseley's X-ray spectrometer, makes use of the variation in deflection produced by different isotopes in a magnetic field. Positive (anode) rays are passed between two electrically charged plates, A and B, and are then brought to a focus on the photographic plate, C, by means of a magnetic field, generated by the coil, M. The resulting photographic image consists of a series of lines, the intensities of which indicate the relative abundance of the different isotopes. The two mass spectra displayed here are of the elements neon and chlorine.

[38-8]
Presented by Dr F. W. Aston, F. R. S.

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