Optically enhanced discharge excitation and trapping of $^{39}Ar$

TL;DR

This paper demonstrates a method to significantly increase the loading rate of $^{39}Ar$ in an atom trap by optically pumping specific transitions, enabling more efficient dating of water samples.

Contribution

It introduces a novel optical pumping technique to enhance metastable atom generation in $^{39}Ar$, improving trap loading efficiency and reducing sample requirements.

Findings

Two-fold increase in $^{39}Ar$ trap loading rate.

Identification of optimal optical transitions for metastable state excitation.

Calculation and experimental confirmation of frequency shifts in $^{39}Ar$ transitions.

Abstract

We report on a two-fold increase of the $^{39}Ar$ loading rate in an atom trap by enhancing the generation of metastable atoms in a discharge source. Additional atoms in the metastable $1s_5$ level (Paschen notation) are obtained via optically pumping both the $1s_4$ - $2p_6$ transition at 801 nm and the $1s_2$ - $2p_6$ transition at 923 nm. By solving the master equation for the corresponding six-level system, we identify these two transitions to be the most suitable ones and encounter a transfer process between $1s_2$ and $1s_4$ when pumping both transitions simultaneously. We calculate the previously unknown frequency shifts of the two transitions in $^{39}Ar$ and confirm the results with trap loading measurements. The demonstrated increase in the loading rate enables a corresponding decrease in the required sample size, uncertainty and measurement time for $^{39}Ar$ dating, a significant improvement for applications such as dating of ocean water and alpine ice cores.