# Absolute frequency measurement of rubidium 5S-6P transitions

## TL;DR

This paper presents highly precise absolute frequency measurements of rubidium 5S-6P transitions using saturation absorption spectroscopy, improving accuracy and verifying literature values for isotope shifts and hyperfine constants.

## Contribution

It provides the first high-precision absolute frequency measurements of rubidium 5S-6P transitions with uncertainties below 500 kHz.

## Key findings

- Achieved measurement uncertainties of 450 kHz and 20 kHz for the two transitions.
- Verified literature values for isotope shifts and hyperfine constants.
- Derived hyperfine splitting with high accuracy.

## Abstract

We report on measurements on the 5S-6P rubidium transition frequencies for rubidium isotopes with an absolute uncertainty of better than \SI{450}{kHz} for the 5S $\rightarrow$ 6P$_{1/2}$ transition and \SI{20}{kHz} for the 5S $\rightarrow$ 6P$_{3/2}$ transition, achieved by saturation absorption spectroscopy. From the results we derive the hyperfine splitting with an accuracy of \SI{460}{kHz} and \SI{30}{kHz}, respectively. We also verify the literature values for the isotope shifts as well as magnetic dipole constant and the electric quadrupole constant.