Double-Quantum Saturation Spectroscopy in Hydrogen: Measurement of the3P32−3D32Lamb Shift

Abstract

Very narrow saturated double-quantum transitions ($2{}_{}{}^2{}_{}{}^{}S-3\mathrm{}{}_{}{}^2{}_{}{}^{}S, 3{}_{}{}^2{}_{}{}^{}D$) have been observed for atomic H in a He-${\mathrm{H}}_2$ dc discharge using rf and a cw dye laser. The H $3P_{\frac{3}{2}}-3\mathrm{}{D}_{\frac{3}{2}}$ Lamb shift has been measured directly by comparing single- and double-quantum saturation signals to be - 5.5(0.9) MHz, confirming that $3D_{\frac{3}{2}}$ lies lower than the $3P_{\frac{3}{2}}$ state. Further applications of the method are discussed.