For precision atomic magnetometry, inert buffer gas is included in alkali-metal vapor cells to significantly broaden hyperfine transitions, which facilitates optical pumping and reduces diffusive relaxation, while also providing nonradiative excited-state quenching. We show low-buffer gas pressure (below 50 Torr) alkali-metal vapor cells with resolved hyperfine manifolds can also yield high-performance magnetometers. For high polarization in ${}^{87}\mathrm{Rb}$, we optically pump $F=2$ states with narrow linewidth ${\sigma }_{+}$ light, while tuning a probe beam to depopulate $F=1$ states ($\mathrm{\Delta }\nu =6.8\mathrm{GHz}$ from $F=2$). The probe tuning then also provides $F=2$ detection with high optical rotation and low probe broadening; we demonstrate top-bottom gradiometry, within a single 25-Torr, 0.5-${\mathrm{cm}}^3\text{cell}$, that yields an Earth's field free-precession magnetometer sensitivity of 18 $\mathrm{fT}/\sqrt{\text{Hz}}$ with a 1 kHz bandwidth, as well as an RF magnetometer sensitivity of 12 $\mathrm{fT}/\sqrt{\text{Hz}}$ in a small band about 110 kHz.

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• Fine & hyperfine structure
• Lifetimes & widths
• Light-matter interaction
• Lineshapes & shifts
• Nuclear & electron resonance
• Optical pumping
• Zeeman effect