Francis William Aston

Francis William Aston (born Harborne, Birmingham, September 1 1877; died Cambridge, 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".[1]

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Biography and work

Francis Aston was born in Harborne, now part of Greater Birmingham, on September 1, 1877. He was the third child and second son of William Aston and Fanny Charlotte Hollis. He was educated at the Harborne Vicarage School and later Malvern College in Worcestershire where he has a boarder. In 1893 Francis William Aston began his university studies at Mason College (later part of the University of Birmingham) where he was taught physics by John Henry Poynting and chemistry by Frankland and Tilden. From 1896 on he conducted additional research on organic chemistry in a private laboratory at his father’s house. In 1898 he started as a student of Frankland financed by a Forster Scholarship; his work concerned optical properties of tartaric acid compounds. He started to work on fermentation chemistry at the school of brewing in Birmingham and was employed by W. Butler & Co. Brewery in 1900. This period of employment ended in 1903 when he returned to the University of Birmingham under Poynting as an Associate.

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 flow of current through an electronic discharge tube (a gas-filled tube with electrodes under high vacuum. The research, conducted with self-made discharge tubes, led him to the investigate the volume of the Crookes dark space now known as Aston dark space. ^[1][2][3]

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 Joseph John 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 positive 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 was used to separate the different ions, by there 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,

Private life

In his private life he was a sportsman, cross-country skiing and skating in winter time, during his regular visits to Switzerland and Norway, deprived of this winter sports during First World War he started climbing. Between the ages of 20 and 25 he spent a large scale of his spare time cycling. The new invention of motorized vehicles he constructed a combustion engine of his own in 1902 and participated in the Gordon Bennett Race in Ireland in 1903. Not content with these sports he also engaged in swimming, golf, especially with Rutherford and other colleges in Cambridge ^[4] , tennis, winning some prizes at open tournaments in England Wales and Ireland and learning surfing in Honululu in 1909. Coming from a musical family he was capable to play piano, violine and cello at a level that he regularly was played in the concerts at Cambridge. He visited many places around the globe on extensive travel tours starting from 1908 when he visited and ending with a trip to Australia and New Zealand in 1938-1939.^{[5] [6]}

Isotopes (publ. in 1922) and Mass-spectra- and Isotopes (publ. in 1933) are his most well-known publications.

The lunar crater Aston was named in his honour.

References