Lund and Uppsala
Siegbahn studied at Lund and received his doctorate in 1911, initially researching electricity and magnetism. He became a professor there and moved to Uppsala in 1923. X-ray spectroscopy and the design of its instruments became central to his work.
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Precision X-ray spectra
He improved vacuum pumps and X-ray tubes and designed spectrographs, gratings and precise angular measurements. More accurate spectral data helped investigate energy relationships in atomic electron shells. His book Spektroskopie der Röntgenstrahlen, published in 1923 and later revised, brought this work together.
Nuclear research in Stockholm
In 1937 Siegbahn became director of the Nobel Institute’s experimental-physics department in Stockholm. It developed cyclotrons and other equipment for nuclear reactions and radioactive isotopes. His son Kai later held a chair in Uppsala but was honoured for a different programme, high-resolution electron spectroscopy.