Isotope shift and hyperfine splitting of the $4s\to 5p$ transition in potassium

Alexandra Behrle, Marco Koschorreck, Michael Köhl

We have investigated $4s{}^2{S}_{1/2}\to 5p{}^2{P}_{1/2}$ transition ($D_1$ line) of the potassium isotopes ${}^{39}$K, ${}^{40}$K, and ${}^{41}$K using Doppler-free laser saturatio…