Precision measurement of the ionization energy of Cs I

TL;DR

This paper reports highly precise measurements of the ionization energy of cesium using advanced laser spectroscopy, significantly reducing uncertainty and refining quantum defect values for various Rydberg series.

Contribution

The study provides the most accurate ionization energy of cesium to date and improves quantum defect values for multiple Rydberg series, enhancing atomic data precision.

Findings

Ionization energy of Cs determined with a relative uncertainty of 5×10⁻¹¹

Improved quantum defect values for n$p_{1/2}$, n$p_{3/2}$, n$s_{1/2}$, and n$d_{5/2}$ series

High-precision UV spectroscopy in ultracold Cs atoms used for measurements

Abstract

We present absolute-frequency measurements for the transitions from the 6s$_{1/2}$ ground state of $^{133}$Cs to $n$p$_{1/2}$ and $n$p$_{3/2}$ Rydberg states. The transition frequencies are determined by one-photon UV spectroscopy in ultracold samples of Cs atoms using a narrowband laser system referenced to a frequency comb. From a global fit of the ionization energy $E_\mathrm{I}$ and the quantum defects of the two series we determine an improved value of $E_\mathrm{I} = h c \cdot 31 406.467 732 5(14)$ cm$^{-1}$ for the ionization energy of Cs with a relative uncertainty of $5\times10^{-11}$. We also report improved values for the quantum defects of the $n$p$_{1/2}$, $n$p$_{3/2}$, $n$s$_{1/2}$, and $n$d$_{5/2}$ series.