Frensis Aston
Great BritainBiography of Francis Aston
Francis William Aston, an English chemist and Nobel laureate in Chemistry in 1922, was born in Harborne, near Birmingham, to William Aston, a farmer and ironmonger, and Fanny Charlotte (Hollis) Aston, the daughter of a successful Birmingham gunsmith. Francis was the third child among seven siblings. He spent his childhood on his parents' farm, where he developed an early interest in science and conducted his own scientific experiments in an improvised laboratory.
From 1889 to 1891, Aston attended Harborne Parish School, and from 1891 to 1893, he studied at Malvern College, where he was the top student in his class. In 1893, Aston enrolled at Mason College in Birmingham (now the University of Birmingham), studying chemistry under W.O. Tilden and P.F. Frankland, and physics under J.G. Poynting. In 1898, he received the Foster Scholarship, which allowed him to return to Mason College and work with Frankland on studying the optical properties of substitution products of wine acid. He published the results of his research in 1901. However, the scholarship did not provide enough funding, so from 1900 to 1903, Aston worked as a chemist at a brewery, specializing in fermentation chemistry. During this time, he built a laboratory at his father's house and constructed the necessary equipment for measuring electric discharges in vacuum tubes. His work earned him a scholarship from the newly established University of Birmingham, where he worked with Poynting from 1903 to 1908. Here, Aston investigated the phenomenon known as "Crookes dark space" (named after the English chemist William Crookes), which refers to the space that appears between the cathode and the negative glow that occurs when an electric current is passed through a tube containing low-pressure gas. He discovered that the dimensions of this dark space were proportional to the pressure and electric current, and that another primary dark space exists near the cathode (now known as the "Aston space").
After completing a circumnavigation trip in 1909, Aston became an assistant to J.J. Thomson at the Cavendish Laboratory in the University of Cambridge and the Royal Institution in London. Although Aston had a background in chemistry, his knowledge of cathode rays and positive rays allowed him to conduct experiments at the intersection of physics and chemistry. Thomson tasked Aston with improving an apparatus called a spherical deflection tube, which measures the ratio of charge to mass for a beam of positively charged particles. At the same time, Thomson was interested in Frederick Soddy's ideas on isotopy and attempted to separate neon isotopes. To do so, he invented an apparatus for fractionating neon and a slightly heavier component, which Thomson named "metaneon". To measure the weight of the fractionated products, Aston constructed quartz microbalances sensitive to one billionth of a gram. Aston achieved promising, although not definitive, results. However, his work was interrupted by the outbreak of World War I, and he had to change the direction of his research. During the war, Aston worked at the Royal Aircraft Establishment in Farnborough, studying the effects of atmospheric conditions on aircraft structures. Nonetheless, he found the time and opportunity to design a new apparatus to solve the problem of neon, which he constructed in 1919 and called the mass spectrograph. This apparatus increased the speed of positively charged ions passing through an electric field by using a strong magnetic field to focus these ions onto a photographic plate. Since heavy atoms are deflected less than light atoms, particles of different masses were separated and formed a mass spectrum. The pattern that appeared upon the impact of particles on the photographic plate allowed Aston to make assumptions regarding their mass and magnitude. Thus, he discovered that almost all elements have multiple isotopes.
In his further research, Aston formulated the rule of whole numbers, which states that atomic masses are always expressed as whole numbers. However, observations showed that some atomic masses could not be precisely expressed as whole numbers. Aston believed that the presence of fractional atomic masses was explained by the existence of isotopes. For example, he discovered that there are 10 isotopes of neon with an atomic mass of 20 for each isotope of neon with an atomic mass of 22, resulting in the average atomic mass of neon being 20.2. This mixture of isotopes does not affect the chemical properties of neon, which depend solely on its atomic number, i.e., its position in the periodic table. Aston's discovery was initially seen as experimental confirmation of the hypothesis put forward in 1815 by English chemist William Prout, which stated that all atoms are composed of common constituents. However, later research showed that this viewpoint led to an overly simplified understanding of the structure of matter. In 1922, Aston was awarded the Nobel Prize in Chemistry "for his discovery, made with the help of his own invention, the mass spectrograph, of isotopes in a large number of non-radioactive elements and for his formulation of the whole number rule." He was presented with the award by H.G. Söderbaum on behalf of the Royal Swedish Academy of Sciences. Söderbaum stated, "Thanks to Aston's discovery, the mystery that had puzzled chemists for over a hundred years has finally been solved, and the supposition that has fascinated humanity for millennia has been confirmed."
True to his motto of "Again, again, and again test," Aston developed larger and more powerful mass spectrographs in 1927 and 1935, which allowed him to measure very slight deviations from the whole number rule. He explained these deviations as a result of the loss of atomic mass through its transformation into binding energy between particles within the nucleus. The more tightly bound the nuclear charges are, the more the deviation in mass depends on the sum of their individual masses. By measuring these deviations, Aston plotted them against the atomic number of many elements. The results of his research contributed to the understanding of the abundance and stability of elements, as well as the later process of releasing atomic energy from the atom's nucleus. Apart from his scientific pursuits, Aston was an avid skier, swimmer, mountaineer, cyclist, tennis player, golfer, and enthusiast of sea voyages. He was also a skilled amateur photographer and musician. Aston never married. He died on November 20, 1945, in Cambridge. In accordance with his will, his large estate was bequeathed to Trinity College, Cambridge.
Aston served on the council of Trinity College (where he taught until his death) and was a member of the Royal Society, a foreign member of the Italian National Academy of Sciences, and an honorary member of the USSR Academy of Sciences. He received numerous awards, including the John Scott Medal from the City of Philadelphia (1923), the Hughes Medal (1920) and Royal Medal (1938) from the Royal Society, as well as the Duddell Medal and the Physical Institute's Award (1941). From 1936 to 1945, Aston served as the chairman of the Commission on Atomic Weights of the International Union of Pure and Applied Chemistry.
