Aston, Francis William, 1877-1945

Francis William Aston (1877-1945), experimental physicist, was educated at Malvern College and Mason College, Birmingham. He carried out research with P.F. Frankland and later J.H. Poynting, before becoming research assistant to Sir J.J. Thomson, 1910-1913, with whom he worked on the mass-analysis of positive rays by the parabola method. He was a student at Cambridge in 1913, then technical assistant at the Royal Aircraft Establishment, 1914-1918, before returning to Cambridge as a research fellow at Trinity College in 1920. At Cambridge, he built a mass-spectrograph and achieved the velocity focusing of positive rays. His second mass-spectrograph was used to carry out a complete survey of the elements between 1927 and 1935. Aston was made a Fellow of the Royal Society in 1921 and received the Nobel Prize for chemistry in 1922.

Francis William Aston was born at Harborne, near Birmingham on 1 September 1877. He was educated at Malvern College and Mason College (which later became the University of Birmingham) where he studied chemistry under P.F. Frankland and W.A. Tilden and Physics under J.H. Poynting. Awarded the Forster scholarship he studied optical rotation with Frankland, 1898-1900. Aston then left academic life for three years to work for a firm of brewers. However, he continued to research privately, particularly with discharge tubes. This work attracted the attention of Poynting and in 1903 Aston returned to Birmingham to continue his research in Poynting's department. At the end of 1909 he accepted an invitation from Sir J.J. Thomson to work as his assistant on positive rays at the Cavendish Laboratory, Cambridge. He took a B.A. degree by research in 1912 and in 1913 the university recognised his distinction in research by electing him as Clerk Maxwell student. It was during this period that he obtained definite evidence for the existence of two isotopes of the inert gas neon. Aston's research was interrupted by the First World War during which he worked at the Royal Aircraft Establishment, Farnborough, principally on aircraft fabrics and dopes (synthetic coatings). In 1919 he returned to the Cavendish Laboratory to research the separation of the isotopes of neon. This was accomplished by his invention of the mass spectrograph, an apparatus which enabled him to utilise the very slight differences in mass of the two isotopes to effect their separation. He extended this principle to other chemical elements, discovering, in a series of measurements, 212 of the naturally occurring isotopes. From this work he formulated 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. In 1920 Aston was elected to the Fellowship of Trinity College Cambridge. He was elected FRS in 1921 (Hughes Medal 1922; Bakerian Lecture 1927), and in 1922 he was awarded the Nobel Prize for 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'. Aston's interests in astronomy and photography led to his membership of expeditions that studied eclipses in Sumatra (1925), Canada (1932) and Japan (1936). He served as President of the International Union of Chemistry's Commission on Atoms, 1935-1945. He continued to live and work in Cambridge, where he died on 20 November 1945.