Calibration-Free Analysis of Li Isotope Ratios Using Laser Ablation and Laser Absorption Spectroscopy.

Area of Science:

• Analytical Chemistry
• Atomic Spectroscopy
• Materials Science

Background:

• Accurate lithium isotope ratio measurements are crucial for nuclear energy, safeguards, and geochemistry.
• Traditional methods often require calibration and can be time-consuming.

Purpose of the Study:

• To develop a rapid, calibration-free, all-optical method for high-precision lithium isotope ratio measurements in solid materials.
• To enable accurate determination of lithium isotope ratios and atomic column densities.

Main Methods:

• Utilized laser ablation combined with tunable laser absorption spectroscopy.
• Employed a new asynchronous method to acquire time-resolved, high-resolution absorption spectra of lithium isotopes (6Li and 7Li).
• Applied a physics-based fitting model incorporating hyperfine structure for data analysis.

Main Results:

• Achieved narrow line widths (Doppler temperatures ≤400 K) enabling high signal-to-noise ratio resolution of isotope peaks.
• Demonstrated relative isotopic precisions of 0.6-1.8% for 30-second acquisitions.
• Showed relative accuracy within -0.3% to -5% compared to ICP-MS measurements without external calibration.

Conclusions:

• The developed method offers a rapid and precise approach for lithium isotope determination in solid materials.
• The calibration-free nature and high accuracy make it suitable for various applications, including nuclear energy and geochemistry.
• This all-optical technique advances the field of isotopic analysis in solid-state materials.