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Frederick Grant Banting
Sir Frederick Grant Banting was a Canadian medical scientist.
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Francis William Aston1.9.1877

Wikipedia (09 Sep 2014, 15:35)

Francis William Aston FRS (1 September 1877 – 20 November 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. He was a fellow of the Royal Society and Fellow of Trinity College, Cambridge.


With a scholarship from the University of Birmingham he pursued research in physics following the discovery of X-rays and radioactivity in the mid-1890s. Aston studied the current through a gas-filled tube. The research, conducted with self-made discharge tubes, led him to investigate the volume of the Aston dark space.

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 ray and then 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 was discovered by Wilhelm Wien in 1908; combining magnetic and electric fields allowed the separation of different ions by their ratio of charge and mass. Ions of a particular charge/mass ratio would leave a characteristic parabolic trace on a photographic plate, demonstrating for the first time that atoms of a single element could have different masses. The first sector field mass spectrometer was the result of these experiments.

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 that he reported on in 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, Aston became a member of the International Committee on Atomic Weights, 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 [as 16], 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.

Isotopes and Mass-spectra and Isotopes are his most well-known books.

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