FRANCIS WILLIAM ASTON (British) (1877 - 1945)
Physicist/Chemist.
Invented the mass spectrograph, an instrument by which the stable chemical elements can be analysed in terms of their separate isotopes. Isotopes and varieties of the same element having the same chemical properties but different masses – for example uranium 235 and uranium 238 which have to be separated to make nuclear fuel or nuclear weapons. Aston working with J.J. Thomson of Cambridge set out to find if stable elements had isotopes like the known radioactive ones. In 1919 he perfected a mass spectrograph in which isotopes were separated by an ingenious combination of electric and magnetic fields. He rapidly analysed some 50 of the 92 known elements and demonstrated that nearly all possessed isotopes were not whole number multiples of the mass of the simplest atom, hydrogen. Instead they showed a mass defect accounted for (according to Einstein’s famous equation e=mc2) by the energy used up in binding the atomic nuclei together. For this significant level amount Aston was awarded the Nobel prize for Chemistry (1922).
Our understanding of isotopes is fundamental to our understanding of atomic nature.
compiler:benny
