The Stark Effect

Abstract

In this chapter, we consider a static electric field interacting with the atom. For an atom in an electric field, it will be energetically favourable to have its inherent charges displaced such that an electric dipole moment is induced. This is the Stark effect, and it is typically smaller than the Zeeman effect. The Stark effect works differently for hydrogen than it does for all other atoms because the first-order effect tends to cancel for all atoms with more than a single electron. The first and second orders are referred to as the linear and quadratic Stark effects. The reason for the difference between hydrogen and other atoms is that the Hamiltonian has odd parity. As a consequence, the first-order perturbation term will cancel, with the only exception being when two states of different parities are degenerate.