Hyperfine Structure of Atomic Phosphorus

Abstract

The spin-exchange optical polarization method was used to determine the sign and the magnitude of the hyperfine interaction constant in the ground ${(3p)}^{3}^{4}S_{\frac{3}{2}}$ state of atomic ${\mathrm{P}}^{31}$. The measurements were made by monitoring the transmission of circularly polarized rubidium ${D}_{1}$ ($5{P}_{\frac{1}{2}}\ensuremath{\rightarrow}5{S}_{\frac{1}{2}}$) resonance radiation through a flask containing rubidium, atomic phosphorus, and a buffer gas as a function of the frequency of an external radio-frequency field. The value for the hyperfine interaction constant of ${\mathrm{P}}^{31}$ obtained by extrapolation to zero pressure in a helium buffer gas is $A({\mathrm{P}}^{31})=+(55055691\ifmmode\pm\else\textpm\fi{}8) \mathrm{cps}/sec.$ The pressure shifts in cycles/sec/mm Hg of the phosphorus hyperfine interaction constant for helium and neon buffer gases are +3.61\ifmmode\pm\else\textpm\fi{}0.23 and +6.73\ifmmode\pm\else\textpm\fi{}0.15, respectively.