From Liverpool to Edinburgh
Barkla studied mathematics and physics in Liverpool and went to the Cavendish Laboratory in 1899 to work with J.J. Thomson. After appointments in Liverpool and London, he became professor of natural philosophy at Edinburgh in 1913 and remained there until his death in 1944.
Scattered and characteristic radiation
From 1902 he investigated secondary radiation from materials exposed to X-rays. He distinguished scattered radiation from characteristic fluorescent radiation associated with the material itself. Element-specific spectral lines supplied information about atoms rather than merely a measure of overall radiation intensity.
Polarisation and atomic structure
Barkla also studied X-ray polarisation, absorption and photographic effects. Polarisation supported the connection between X-rays and light, while characteristic spectra linked the radiation with atomic structure. These investigations formed the work recognised by the 1917 physics prize.