High-Precision Multiphoton Ionization of Accelerated Laser-Ablated Species

Abstract

We demonstrate that the pulsed-time structure and high-peak ion intensity provided by the laser-ablation process can be directly combined with the high resolution, high efficiency, and low background offered by collinear resonance ionization spectroscopy. This simple, versatile, and powerful method offers new and unique opportunities for high-precision studies of atomic and molecular structures, impacting fundamental and applied physics research. We show that even for ion beams possessing a relatively large energy spread, high-resolution hyperfine-structure measurements can be achieved by correcting the observed line shapes with the time-of-flight information of the resonantly ionized ions. This approach offers exceptional advantages for performing precision measurements on beams with large energy spreads and allows measurements of atomic parameters of previously inaccessible electronic states. The potential of this experimental method in multidisciplinary research is illustrated by performing, for the first time, hyperfine-structure measurements of selected states in the naturally occurring isotopes of indium,In113,115. Ab initio atomic-physics calculations have been performed to highlight the importance of our findings in the development of state-of-the-art atomic many-body methods, nuclear structure, and fundamental-physics studies.

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Plain Language Summary

The study of radioactive nuclei, interactions among electrons and nuclear particles, and new physics beyond the standard variety of fundamental particles and forces has led to the development of precise and efficient laser-based experimental techniques. However, far-reaching applications are often limited by the reliance on complex devices that are available only at large experimental facilities. Here, we present a simple yet powerful tabletop approach to highly sensitive and precise measurements of atomic and molecular structure.

Our approach combines distinct features provided by pulsed-laser ablation and collinear resonance ionization spectroscopy, a laser spectroscopy technique developed at CERN. We show that even for ion beams possessing a relatively large energy spread, high-resolution measurements of hyperfine structure can be achieved by correcting the observed line shapes with the time-of-flight information of resonantly ionized ions. This combination offers unique advantages for precisely measuring atomic parameters of previously inaccessible electronic states.

We illustrate the potential of this experimental method in multidisciplinary research by performing, for the first time, hyperfine-structure measurements of selected states in atomic indium. We compare our results with first-principles atomic physics calculations to highlight the importance of our findings in nuclear structure, atomic theory, and studies of fundamental symmetries.

Our approach should have further applications in atomic and molecular spectroscopy as well as in the study of laser-generated plasmas.