Demonstrated by the fact that the 2p(1/2) state is slightly lower in energy than the 2s(1/2) state, FTP, identify this phenomenon named after the 1955 recipient of the Nobel Prize in Physics.
This phenomenon was first measured when its namesake utilized the Zeeman effect and exposed a beam of hydrogen atoms to microwave radiation at 2395 megahertz.  The Planck relationship demonstrated that the energy separation in question was 4.372x10-6 electron volts.  It results from an electron's self-interaction and its namesake discovered that there was a slight movement of the corresponding spectral lines.  Demonstrated by the fact that the 2p(1/2) state is slightly lower in energy than the 2s(1/2) state, FTP, identify this phenomenon named after the 1955 recipient of the Nobel Prize in Physics.
This phenomenon was first measured when its namesake utilized the Zeeman effect and exposed a beam of hydrogen atoms to microwave radiation at 2395 megahertz.  
Lamb shift