Background
Francis Aston was born on September 1, 1877, in Harborne, now part of Birmingham. Aston was the second son of William Aston, a metal merchant and farmer, and Fanny Charlotte Hollis, the daughter of a Birmingham gunmaker.
Aston spent four years at Malvern College, Malvern, Worcestershire, England.
In 1893 Aston entered Mason’s College, Birmingham, where he studied for the London intermediate science examination. (Photo: Masons College Edmund Street Birmingham, United Kingdom, c. Phyllis Nicklin, 1960)
Francis Aston in his laboratory at Cambridge University. In 1922 he was awarded the Nobel prize for chemistry for his discovery of isotopes Photograph: Science & Society Picture Library/Getty Images.
Francis Aston, English chemist and physicist who won the 1922 Nobel Prize in Chemistry.
The Nobel prize medal for chemistry awarded to Francis Aston in 1922.
Francis William Aston, 1877 – 1945, English chemist and physicist who won the 1922 Nobel Prize in Chemistry.
Francis William Aston, 1877 – 1945, English chemist and physicist who won the 1922 Nobel Prize in Chemistry.
Francis William Aston
Portrait of Francis Aston at Cavendish Laboratory, University of Cambridge. Photo date: June 1934. AIP Emilio Segrè Visual Archives, Bainbridge Collection.
In 1922, Aston received Hughes Medal from the Royal Society of London "for his discovery of isotopes of a large number of the elements by the method of positive rays".
Aston received the Mackenzie Davidson Medal of the Röntgen Society in 1920.
In 1923 Aston was awarded the John Scott Legacy Medal and Premium, which is presented to men and women whose inventions improved the "comfort, welfare, and happiness of human kind" in a significant way.
Aston was awarded the Duddell Medal of the Physical Society in 1944.
In 1921, Francis William Aston was elected a Fellow of the Royal Society.
Francis Aston was born on September 1, 1877, in Harborne, now part of Birmingham. Aston was the second son of William Aston, a metal merchant and farmer, and Fanny Charlotte Hollis, the daughter of a Birmingham gunmaker.
After primary education at Harbonne vicarage school, Aston spent four years at Malvern College. In 1893 he entered Mason’s College, Birmingham, where he studied for the London intermediate science examination with the chemists W. A. Tilden and P. F. Frankland and the physicist J. H. Poynting. In 1898 he obtained a Forster Scholarship to work with Frankland on the stereochemistry of dipyromucyltartaric acid esters. Simultaneously he took a course in fermentation chemistry, and from 1900 to 1903 he earned a living as a brewery chemist at Wolverhampton.
Finishing his studies, Aston returned to Birmingham University (formed from Mason’s College in 1900) from 1903 to 1908 as a physics research student with Poynting, and after a world tour in 1909, he spent a term at Birmingham as an assistant lecturer. From 1910 to 1919 Aston worked with J. J. Thomson at the Cavendish Laboratory, Cambridge, and the Royal Institution, London; first as a personal assistant, then from 1913 as a Clerk Maxwell Scholar. This period was interrupted by the war, during which Aston returned to chemistry as a technical assistant at the Royal Aircraft Establishment, Farnborough. In 1919 he was elected a fellow of Trinity College, Cambridge, where he spent the remainder of his life.
Like most of J. J. Thomson’s associates, he acquired an interest in finance, and in consequence of skilled investment, he was able to leave a large estate to Trinity College and several scientific beneficiaries.
Although Aston liked to recall that his first two publications were on organic chemistry, these two papers broke no new ground although they did exhibit his talent for devising ingenious apparatus. The appearance of Thomson’s Conduction of Electricity Through Gases in 1903 opened up, for Aston the chemist, the physicist’s world of cathode rays, positive rays, and X rays. Already an expert glassblower, and trained by Frankland in “extreme care and meticulous accuracy,” he began to work under Poynting on the variable structure of the phenomena observed during gaseous conduction at low pressures. He was particularly interested in the variation, with pressure and current, of the length of the dark space between the cathode and the negative glow named after W. C. Crookes.
By making special Geissler discharge tubes with movable aluminum cathodes, Aston was able to obtain a sufficiently well-bounded Crookes space to demonstrate that its length was proportional to where P is the pressure and C is the current. In 1908, while using hydrogen and helium, he detected a new “primary cathode dark space,” about a millimeter thick and directly adjoining the cathode. This phenomenon now bears Aston’s name. Research on the relationship between the Crookes dark space and current, voltage, pressure, and electrode nature and design continued intermittently until 1923. Aston then abandoned it in order to devote all his attention to isotopes.
When Aston became Thomson’s assistant in 1910, he was given the task of improving the apparatus in which a beam of positively charged particles (positive rays), which emerged through a perforated cathode in a discharge tube, was deflected by perpendicularly arranged electric and magnetic fields into sharp, visible parabolas of constant e/m (charge over mass). Aston produced an improved spherical discharge tube, finely engineered cathode slits, an improved pump, a coil for detecting vacuum leaks, and an ingenious camera for photographing the parabolas. In 1912 he thought this apparatus for positive ray analysis gave a rigorous proof that all the individual molecules of any given substance had the same mass. This Daltonian belief was rudely shattered in the same year when Thomson obtained two parabolas, of mass 20 and 22, for neon. There were two obvious possibilities: if neon had a true atomic weight of 20 (instead of 20.2), then either mass 22 was an unknown hydride, NeH2, or a new element, meta-neon. Thomson investigated the first possibility and left Aston to check the unlikely alternative.
Aston, who was sympathetic toward F. Soddy’s contemporary ideas on radioactive isotopes, tried to separate the meta-neon by fractional distillation, and later by diffusion. He invented a quartz microbalance, which was sensitive to 10-9 gram, to measure the density of the minute heavier fraction. The partial separation of a new element, with the same properties as neon, was announced in 1913; Thomson, however, remained doubtful. During the war, Aston had time to think over the problem and to debate the possibility of the existence of natural isotopes with the skeptical F. A. Lindemann.
In 1919, to test the neon isotope hypothesis, Aston built a positive ray spectrograph, or mass spectrograph, with a resolving power of I in 100 and an accuracy of I part in 103. The design was based upon an optical analogy. Just as white light can be analyzed into an optical spectrum by a prism, so an electric field will disperse a beam of heterogeneous positive rays. By arranging a magnetic field to deflect the dispersed rays in the opposite direction, but in the same plane, rays of uniform mass can be focused into a mass spectrum on a photographic plate, irrespective of their velocities. This was a great advance on Thomson’s apparatus, where the arrangement of the fields produced parabolas that were dependent on the velocities of the positive rays. Aston adopted several methods to calculate the masses of the particles, including comparison with a calibration curve of reference lines of known masses. In the case of neon, the intensities of the 20 and 22 mass lines implied a relative abundance of about 10: 1, enough to produce an average mass of 20.2, the known atomic weight of neon. Neon was isotopic.
Two larger mass spectrographs were built. The second (1927) had five times more resolving power and an accuracy of 1 in 104; the third (1935) had a resolving power of 1 in 2000 and a claimed accuracy of 1 in 105. The latter instrument proved difficult to adjust, and World War II intervened before any significant work could be done with it. By then, however, Aston’s instruments had been surpassed by the mass spectrometers developed by A. J. Denmpster (1918), K. T. Bainbridge (1932), and A. O. Nier (1937).
Aston’s personal motto, “Make more, more, and yet more measurements,” led him to analyze successfully all but three of the nonradioactive elements in the periodic table. But since the mass spectrograph was unsuitable for detecting minute amounts of isotopes, he missed finding those of oxygen and hydrogen. In 1930 Aston showed how his instrument could be used photometrically to determine and correct chemical atomic weights. Here much depended on his brilliant development of photographic plates that were highly sensitive to positive ions.
In December 1919 Aston announced the “whole number rule” that atomic masses were integral on the scale O16 (a notation introduced by Aston in 1920). Fractional atomic weights were merely “fortuitous statistical effects due to the relative quantities of the isotopic constituents,” and the elements were to be defined physically by their atomic numbers, rather than in terms of isotopic mixtures. Prout’s hypothesis (1816), that all elements were built up from atoms of a common substance, appeared to be vindicated at last.
Aston’s work, therefore, provided important insights into the structure of the atom and the evolution of the elements. At first, the only hydrogen appeared to violate the whole-number rule. Aston explained this seeming violation as due to the “loss” of mass within this atom by binding energy; mass was additive only when nuclear charges were relatively distant from one another. This concept of “packing” had been proposed on theoretical grounds by W. D. Harkins (1915), and derived ultimately from J. C. G. Marignac (1860). However, it soon became clear that all elements deviated slightly from whole numbers. In 1927, with his second machine, Aston measured and codified the deviations in terms of the “packing fraction” (the positive or negative deviation of an atomic mass from an integer divided by its mass number). By plotting these fractions against mass numbers, Aston obtained a simple curve which gave valuable information on nuclear abundance and stability.
Aston died in Cambridge at the age of 68 in November 1945, three months after Hiroshima was destroyed by an atomic bomb that his pioneering work had helped to create.
Francis William Aston was conservative in politics.
Francis William Aston was conservative in politics and of no decided religious views. In social life Aston was a bachelor, a poor teacher and lecturer, and a lone worker who detested the thought of experimental collaboration. (Only six out of 143 papers were collaborative.)
He recognized his own fallibility as a theorist, and frequently sought the aid of such mathematical physicists as F. A. Lindemann (Lord Cherwell), R. H. Fowler, and W. W. Sawyer.
Quotations:
"The whole of the hydrogen on the earth might be transformed at once and the success of the experiment published at large to the universe as a new star. "
"It has long been known that the chemical atomic weight of hydrogen was greater than one-quarter of that of helium, but so long as fractional weights were general there was no particular need to explain this fact, nor could any definite conclusions be drawn from it. "
“Should the researcher of the future discover some means of releasing this energy in a form which could be employed, the human race will have at its command powers beyond the dreams of scientific fiction,” Aston told his audience in Stockholm.
“One day man will release and control its almost infinite power. We can only hope he will not use it exclusively in blowing up his next door neighbour.”
In 1921, Francis William Aston was elected a Fellow of the Royal Society.
Aston was also an animal lover, a varied and skilled sportsman, a technically brilliant photographer, and an accomplished amateur musician.
Aston was a keen traveler and he would often combine it with his scientific work. 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.
Francis Aston was a sportsman, cross-country skiing and skating in winter time, during his regular visits to Switzerland and Norway; deprived of these winter sports during the First World War he started climbing. Between the ages of 20 and 25, he spent a large part of his spare time cycling. He also learned surfing in Honolulu in 1909.
Aston had a reputation of a keen golfer and along with Ernest Rutherford, Ralph Fowler and G.I. Taylor made a famous foursome. Swimming and tennis were also his favorite past time and he won many prizes in tennis tournaments.
Coming from a musical family, he was capable of playing the piano, violin and cello at a level such that he regularly played in concerts at Cambridge.
Francis William Aston never married and had no children. “He never married probably because he never gave himself time to settle down,” said Matthew Haley, of Bonhams. As a result, most of his estate went to Trinity College, Cambridge.