A New Heart for Rb Frequency Standards?: The Evacuated, Wall-Coated Sealed Cell

Rb87 hyperfine resonances observed in an evacuated, wall-coated cell, sealed since 1968, exhibit linewidths of ~10 Hz for the narrow Lorentzian feature. The high-resonance Q of 0.65 × 109 shows good promise for the potential use of such cells in Rb frequency standards.