Measurement of the 4S1/2→6S1/2 transition frequency in atomic potassium via direct frequency-comb spectroscopy
AbstractWe present an experimental determination of the 4S1/2→6S1/2 transition frequency in atomic potassium K39, using direct frequency-comb spectroscopy. The output of a stabilized optical frequency comb was used to excite a thermal atomic vapor. The repetition rate of the frequency comb was scanned and the transitions were excited using stepwise two-photon excitation. The center-of-gravity frequency for the transition was found to be νcog=822951698.09(13) MHz and the measured hyperfine A coefficient of the 6S1/2 state was 21.93(11) MHz. The measurements are in agreement with previous values and represent an improvement by a factor of 700 in the uncertainty of the center-of-gravity measurement.