We have measured line shifts of the $3P-nD$ transitions in sodium induced by collisions with helium, argon, and krypton for $n=5\mathrm{} \mathrm{to} 18$. The shifts of the diffuse series transitions increase rapidly with principal quantum number and asymptotically approach the limit predicted by the Fermi model at high quantum numbers.

• Received 10 February 1982

DOI:https://doi.org/10.1103/PhysRevA.26.1473