Doppler-free spectroscopy of an atomic beam probed in traveling-wave fields

We propose a method to probe the precision spectroscopy of an atomic beam using traveling-wave laser beams. The method is demonstrated by measuring the 2 3S - 2 3P transition in a slow helium atomic beam. The first-order Doppler shift could be effectively suppressed by up to three orders of magnitude compared to that induced by the probing light beam. This method avoids using a standing-wave field when probing the spectra, and consequently, it reduces the laser power dependence and eliminates the modulation due to the standing-wave field. Preliminary measurements of the 2 3S - 2 3P transition of 4He indicate that the uncertainty could be reduced to the sub-kHz level.

Automated summary

We propose a method to accurately measure the atomic beam using traveling-wave laser beams. The method is demonstrated by measuring the 2 3S - 2 3P transition in a slow helium atomic beam. The Doppler shift is effectively suppressed, reducing laser power dependence and eliminating modulation. Preliminary measurements indicate reduced uncertainty to sub-kHz level for the 2 3S - 2 3P transition of 4He.