Measured Shifts of Cesium Atomic Lines — Correlation with Electron Density Derived from Widths

The shifts of lines of the sharp, diffuse, and fundamental series of atomic cesium were measured for an rf electrodeless discharge in which the electron density was varied from 0.5 to 3 × ${10}^{14}$ ${\mathrm{cm}}^{-3\mathrm{}}$ with a temperature range from 2600 to 3100°K. The shift values, which ranged from 0.008 to 1.4 Å, agree to ± 20% with the theoretical Stark-broadening predictions for the $6P-10S$, $6P-11S$, $6P-12S$ sharp-series members: $6P-9D$, $6P-10D$, $6P-11D$ diffuse-series members; and the $6D-5F$, $6D-6F$, $6D-7F$, $6D-8F$ fundamental-series members. The measured shifts exhibit a definite trend with quantum number $n$ for all three series. At low values of $n$, measured shifts are greater than those computed from Stark-broadening theory, whereas measured shifts are less than theory for high $n$. We show that certain assumptions in the Stark-broadening theory are not applicable to most of those lines where disagreement between theory and experiment is greatest.