Optical spectroscopy of high-L Rydberg states of argon

High-L fine structure patterns in n=9 and n=17 Rydberg levels of argon have been studied using a Doppler-tuned CO2 laser and a fast beam of argon atoms. Analysis of the measured pattern using the polarization model yields the scalar dipole polarizability and quadrupole moment of the P-2(3/2) Ar+ ion. The results are alpha(S)=6.83(8)a(0)(3) and Q=-0.5177(15)ea(0)(2). Within the precision of this study, no vector component of the structure was observed.