# Efficient, high-resolution resonance laser ionization spectroscopy using weak transitions to long-lived excited states

## TL;DR

This paper demonstrates a method for resonance laser ionization spectroscopy that achieves high efficiency and resolution using weak transitions to long-lived excited states, optimizing laser timing and intermediate state lifetime.

## Contribution

It introduces a novel approach using weak atomic transitions and delayed ionization to enhance efficiency and spectral resolution in laser ionization spectroscopy.

## Key findings

- Achieved 1-10% efficiency in spectroscopy of radioactive nuclei
- Maintained narrow linewidths of tens of MHz
- Model accurately predicts experimental lineshapes and guides optimization

## Abstract

Laser spectroscopic studies on minute samples of exotic radioactive nuclei require very efficient experimental techniques. In addition, high resolving powers are required to allow extraction of nu- clear structure information. Here we demonstrate that by using weak atomic transitions, resonance laser ionization spectroscopy is achieved with the required high efficiency (1-10%) and precision (linewidths of tens of MHz). We illustrate experimentally and through the use of simulations how the narrow experimental linewidths are achieved and how distorted resonance ionization spec- troscopy lineshapes can be avoided. The role of the delay of the ionization laser pulse with respect to the excitation laser pulse is crucial: the use of a delayed ionization step permits the best resolving powers and lineshapes. A high efficiency is maintained if the intermediate level has a lifetime that is at least of the order of the excitation laser pulse width. A model that describes this process re- produces well the observed features and will help to optimize the conditions for future experiments.