In atomic pheesics, tha fine structure describes the splitting of the spectral lines of atoms due tae electron spin and relativistic corrections to the non-relativistic Schrödinger equation. It was first meisuret precisely fer tha hydrogen atom by Albert A. Michelson and Edward W. Morley in 1887, whilk led tae tha theoretical treatment by Arnold Sommerfeld, who introduicet tha fine-structur constant.
- AA. Michelson and E. W. Morley, Amer. J. Sci.34, 427 (1887); Phil Mag. 24, 463 (1887)
- A.Sommerfeld: Zur Feinstruktur der Wasserstofflinien; Naturwissenschaften July 1940, Volume 28, Issue 27, pp 417–423; (in German)