Infrared-X-Ray Double-Resonance Study of2P32−2S12Splitting in Hydrogenic Fluorine

Hydrogenic fluorine atoms in the $2S_{\frac{1}{2}}$ metastable state were produced at 64 MeV by use of a tandem electrostatic accelerator and suitable combinations of stripper and adder carbon foils. A pulsed HBr laser centered at 2382.52 ${\mathrm{cm}}^{-1\mathrm{}}$ was Doppler-shift tuned through the $2S_{\frac{1}{2}}-2\mathrm{}{P}_{\frac{3}{2}}$ energy separation to yield a resonance in Lyman-$\alpha$ x rays at 826 eV. This technique yields a value for the Lamb-shift splitting ($2S_{\frac{1}{2}}-2\mathrm{}{P}_{\frac{1}{2}}$) equal to 3339±35 GHz which is presently in agreement with several quantum electrodynamic calculations.