Karl Manne Siegbahn, Nobel Prize for his contribution to the field of X-ray spectroscopy

3 December 1886, Örebro Nikolai Parish (Sweden) - 26 September 1978, Engelbrekt (Sweden)

Karl Manne Georg Siegbahn enrolled at the University of Lund (Sweden) in 1906 and combined his studies with a position as assistant to Johannes Rydberg, a professor at the University's Institute of Physics.

He received his doctorate in 1911 with his thesis entitled ‘Measurements of the Magnetic Field’ and became a professor.

In 1915, he became Associate Professor of Physics and replaced Ryderg in his post when he died in 1920.

In 1923 he moved to the University of Uppsala where he was a Professor of Physics until 1937, when he was appointed Research Professor of Experimental Physics at the Royal Swedish Academy of Sciences. In the same year, the Physics Department of the Nobel Institute was established and he became its first director.

His scientific research focused on the field of X-ray spectroscopy, a technique for studying the electronic structure of substances through their excitation by X-rays. In this field, he developed new methods and instruments, such as spectrographs, vacuum pumps, and X-ray tubes, which greatly increased the precision of his measurements and made it possible to obtain a virtually complete knowledge of the energy levels of electrons in atoms.

He also developed the so-called ‘Siegbahn notation’ for cataloguing the X-ray spectral lines of the chemical elements. This notation is still used today.

His precise measurements made theoretical breakthroughs in atomic and quantum physics possible. For this, he was awarded the Nobel Prize in Physics in 1924. Curiously, he received the prize a year later, as the Nobel Committee for Physics considered that none of the candidates, including Karl Siegbahn, met the criteria specified by Alfred Nobel, so, in accordance with the statutes of the Nobel Foundation, the prize was suspended until the following year.

Between 1937 and 1956 he was a member of the International Commission of Weights and Measures, of which he later became an honorary member, and was president of the International Physical Union from 1938 to 1947.

He received major awards: Hughes Medal (1934), Rumford Medal (1940), and Duddel Medal (1948) and was invested honoris causa at the Universities of Freiburg, Bucharest, Oslo, and Paris and at the Technical Faculty of Stockholm.

He was a member of the Roya Society of London, the Physical Society of London, the Royal Society of Edinburgh, and the Paris Academy of Sciences, among others.

He had two sons, one of them physicist Kai Manne Börje Siegbahn, who was awarded the Nobel Prize in Physics like him in 1981.