Absolute measurement of the hyperfine splittings of six molecular ~(127)I_(2) lines around the He-Ne/I_(2) wavelength at λ≈633 nm

摘要

With the aid of two diode-laser narrowband spectrometers around 633 nm, we report the measurement of the iodine hyperfine componcnts of the R(60) 8-4, R(125) 9-4 and P(54) 8-4 transitions located -12 GHz from the classical red He-Ne laser stabilized on the R(127) 11-5 transition of ~(127)I_(2), the P(33) 6-3 transition roughly -1 GHz away, the P(39) 6-3 transition 3.4 GHz above, and the R(59) 8-4 and P(53) 8-4 transitions roughly 19 GHz above. The Doppler-free absorption signals were resolved using a third-harmonic detection technique and hyperfine frequency splittings were measured by beat-frequency techniques. The individual hyperfine transitions were linked to a 633 nm He-Ne laser by direct frequency measurements up to 16 GHz. The experimental standard uncertainty was typically below 5 kHz (i.e. relative uncertainty <1×10~(-11)).