Inventory no. 29272 - Former Display Label
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.
Presented by Dr F. W. Aston, F. R. S.