Resonant Frequency of an Atom in an Atomic Clock

[Tom MS]

Beam standard atomic clocks work by changing the magnetic state of a cesium atom by applying a microwave frequency that matches the resonant frequency of a cesium atom. What is this resonant frequency of the atom in terms of actual events that occur on the atomic level?

http://www.nist.gov/pml/div688/grp40/enc-c.cfm

 

[f95toli]

The frequency f corresponds to the energy difference (via E=h*f) between two electron energy levels in the atom.