The linear version of this effect occurs only in the n>1 states of the hydrogen atom, owing to the degeneracy of the 2p and 2s states in a pure Coulomb potential.  
The linear version of this effect occurs only in the n>1 states of the hydrogen atom, owing to the degeneracy of the 2p and 2s states in a pure Coulomb potential.  The ground state of the hydrogen atom exhibits the quadratic version of this effect, as do alkali metal atoms because they approximate a one-electron atom.  FTP, identify this analogue of the Zeeman Effect, in which applied electric fields cause spectral lines to split.
The linear version of this effect occurs only in the n>1 states of the hydrogen atom, owing to the degeneracy of the 2p and 2s states in a pure Coulomb potential.  
Stark effect