Siegbahn precision X-ray wavelength spectroscopy
ID: siegbahn-precision-x-ray-wavelength-spectroscopy
Precision X-ray emission spectroscopy turns closely spaced spectral lines into quantitative constraints on atomic energy levels. Bragg's law makes a crystal an angular ruler for wavelength: resolving nearby directions can reveal components hidden inside an apparently single line. Accurate line positions and the ability to separate two lines are related, but distinct, experimental achievements.
Karl Manne Georg Siegbahn received the 1924 Nobel Prize in Physics; his lecture was delivered on 11 December 1925.[ref]
The X-ray Spectra and the Structure of the Atoms by Karl Manne Georg Siegbahn. Nobel Lectures, Physics 1922–1941; The X-ray Spectra and the Structure of the Atoms, heading, printed p. 81
His son Kai Siegbahn received the 1981 Nobel Prize in Physics for electron spectroscopy.[ref]
Facts on the Nobel Prize in Physics by Nobel Prize Outreach. Family Nobel Prize laureates in physics, Father and son: Manne and Kai Siegbahn
The Barkla characteristic X-ray experiment distinguished element-dependent K and L groups through absorption and excitation. Moseley's law related corresponding line frequencies across chemical elements to atomic number. Measuring the components within those groups asks a further question: which distinct atomic energy differences produce the neighbouring spectral lines?
Siegbahn's lecture organizes measured spectral lines into energy levels and resolved double levels.[ref]
The X-ray Spectra and the Structure of the Atoms by Karl Manne Georg Siegbahn. Nobel Lectures, Physics 1922–1941; Printed pp. 84–86, Figs. 1–2
The payoff is a map of atomic energy differences as well as an element's position in the periodic table. New to topics? Read the docs here!