An undergraduate experiment to determine the hyperfine structure of the 7 ³S₁ → 6 ³P₂ transitions in Hg

Abstract An undergraduate physics experiment is described that uses a Fabry–Perot etalon and digital camera to determine the hyperfine frequency shifts in naturally occurring mercury. Radiation at 546 nm emitted from the 7 3 S 1 state relaxing to the 6 3 P 2 state in a low pressure Hg lamp is selected by an interference filter to pass through the etalon. This produces a series of concentric rings at the focus of the camera lens that are analyzed using bespoke software written for this experiment. Results from the analysis are compared to theoretical calculations of the hyperfine shifts for both the 199 Hg and 201 Hg isotopes.