How did Aston's mass spectrograph work?
The mass spectrograph works by ionizing atoms, accelerating them through an electric field, then deflecting them with a magnetic field. The ions follow curved paths that depend on their mass-to-charge ratio. By focusing these paths onto a photographic plate, we obtain a spectrum of lines, each corresponding to a specific isotope. The apparatus allows us to determine masses with an accuracy of about 1 part in 10,000. I designed it to eliminate velocity variations among ions, using a combination of electric and magnetic fields to achieve sharp focus. This method was a significant improvement over earlier techniques, enabling the discovery of isotopes for over 50 elements. The mass spectrograph and its applications, detailed in my 1920 paper, became an essential tool for nuclear physics and chemistry.
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