Role of Relativistic Effects and Configuration Mixing on the 1s2s3p4P (J=5/2) State of Argon

The first-order matrix elements vanish for the energetic K and L x-rays and Auger transitions for the 1s2s3p4Po5/2 states due to the selection rules governing the spin quantum numbers. However, "spin-for-bidden" transitions are possible when considering higher order multipoles. Cascading to the 1s2p2 4pe levels is possible in the configuration mixing with the 1s2p3s4Po and 1s2p3d4Po terms. We present the results of our relativistic calculations and of the configuration mixing for the case of 1s2s3p 4po5/2 state in argon.