Frequency-comb spectroscopy of the D₁ line in laser-cooled rubidium

Abstract

We have used an optical frequency comb referenced to coordinated universal time (UTC) to perform spectroscopic measurements of the D1 transition in laser-cooled R 85 b and R 87 b. Our measurements of the optical frequencies have uncertainties of 28 kHz for R 85 b and 79 kHz for R 87 b. These measurements were used to calculate the magnetic dipole constant A (P2 1/2) for R 85 b and R 87 b with similar ranges of uncertainty. Previously, A (P2 1/2) for these isotopes was determined with a stated 7â€"15 kHz uncertainty level; however, there is a large discrepancy, 140 kHz for R 85 b and 2.2 MHz for R 87 b, between the two apparently most precise measurements. Our transition frequency measurements, which avoid saturated absorption spectroscopy and transfer resonator systematics, help resolve this disagreement. © 2008 The American Physical Society.