Francis William Aston (September 1 1877 – November 20 1945) was a British chemist and physicist who won the 1922 Nobel Prize in Chemistry "for his discovery, by means of his mass spectrograph, of isotopes, in a large number of non-radioactive elements, and for his enunciation of the whole-number rule.
After the death of his father, and a trip around the world in 1908, he was appointed lecturer at the University of Birmingham in 1909 but moved to the Cavendish Laboratory in Cambridge on the invitation of J. J. Thomson in 1910.
Joseph John Thomson revealed the nature of the cathode rays and the discovered the electron and he was now doing research on the positively charged "Kanalstrahlen" discovered by Eugen Goldstein in 1886. The method of deflecting particles in the "Kanalstrahlen" by magnetic fields, discovered by Wilhelm Wien in 1908, and electric fields were used to separate the different ions by their charge and mass. The first sector field mass spectrometer was the result of these experiments. The ions followed a parabolic flight path and were recorded on photographic plates from which their exact mass could be determined by the mass spectrometer.
It was speculations about isotopy that directly gave rise to the building of a mass spectrometer capable of separating the isotopes of the chemical elements. Aston initially worked on the identification of isotopes of the element neon and later chlorine and mercury. First World War stalled and delayed his research on providing experimental proof for the existence of isotopes by mass spectroscopy and during the war Aston worked at the Royal Airforce Establishment in Farnborough as a Technical Assistant working on aeronautical coatings.
After the war he returned to research at the Cavendish Laboratory in Cambridge, and completed building his first mass spectrograph (now mass spectrometer) that he reported on 1919. Subsequent improvements in the instrument led to the development of a second and third instrument of improved mass resolving power and mass accuracy. These instruments employing electromagnetic focusing allowed him to identify 212 naturally occurring isotopes. In 1921, F. W. Aston became a fellow of the Royal Society and received the Nobel Prize in Chemistry the following year.
His work on isotopes also led to his formulation of the Whole Number Rule which states that "the mass of the oxygen isotope being defined, all the other isotopes have masses that are very nearly whole numbers," a rule that was used extensively in the development of nuclear energy. The exact mass of many isotopes was measured leading to the result that hydrogen has a 1% higher mass than expected by the average mass of the other elements. Aston speculated about the subatomic energy and the use of it in 1936.
Aston was a skilled photographer and interested in astronomy. He joined several expeditions to study solar eclipses to Benkoeben in 1925, Sumatra in 1932; Memphri in Canada 1936 and Kamishri in Japan. He also planned to attend expeditions to South Africa in 1940 and Brazil in 1945 in later life. Aston died in Cambridge on November 20, 1945,
Isotopes (publ. in 1922) and Mass-spectra- and Isotopes (publ. in 1933) are his most well-known publications.