Past exam of the chemistry course of the year 3 of the natural sciences course of the University of Cambridge / 2022 / Paper 2A / Section B / 21 / a / iv / Solution

The largest applied field givesFor parallel polarization, adjacent allowed M values in a $J,K$ component are separated byAlready at $K=1$ this is $2.24\times 10^{-4}\mathrm{c}{\mathrm{m}}^{-1}$ for $J=2$ and $8.96\times 10^{-5}\mathrm{c}{\mathrm{m}}^{-1}$ for $J=3$. Both exceed the stated $2\times 10^{-5}\mathrm{c}{\mathrm{m}}^{-1}$ resolution, and larger $|K|$ gives larger first-order spacings. The spectrometer should resolve suitable Stark components, provided their physical linewidths and signal-to-noise permit it. This predicts resolvable splittings rather than incorrectly comparing the maximum level shift directly with instrumental resolution.