Laser-Driven forbidden transitions to high-L states in He

Transitions, driven by a CO2 laser, between the 7S1 state and n=9 manifold of states in He have been observed by monitoring the optical emission from the 7S1 state. In addition to the normally expected ΔL=1 transition to the P1 state, clearly resolved transitions have also been observed to the even-parity states with L=2, 4,Acirc 6,Acirc andAcirc 8. The high-L-state transitions are observed because of a combination of diamagnetic Zeeman and motional Stark-effect mixing. A theory has been developed which describes the line shapes of these forbidden transitions.