Characteristic X-Ray

X-ray emitted from an excited atom when an outer-shell (e.g. L) electron jumps in to fill an inner-shell (e.g. K) vacancy. It has energy characteristic of the atom and can therefore be used for analytical purposes. Its energy is the difference between the energies of the atom with an inner-shell vacancy and the same atom with an outer-shell vacancy. The emission of the excess energy when an atom de-excites (decays or relaxes) can alternatively be achieved by the production of an Auger electron. The transitions that produce characteristic x-rays from barium are shown below.

Some or all content above used with permission from J. H. Wittke.