Depth profile analysis and high-resolution surface mapping of lithium isotopes in solids using laser-induced breakdown spectroscopy (LIBS)

Abstract

Lithium isotopic analysis is of interest in various fields from biology to energy. In addition to analytical methods commonly used for that purpose, a new complementary method for determining the spatial resolution of isotopic ratio in solid samples was previously developed: laser induced self-reversal isotopic spectrometry (LIBRIS), derived from laser-induced breakdown spectroscopy (LIBS). In this paper, we present a proof of concept of fast spatially-resolved quantitative isotopic analysis of lithium by LIBS both in depth (z resolution) and in configuration of high-resolution surface mapping (x and y resolution). First, a depth profile measurement where a 9% relative uncertainty on the 6Li isotopic ratio and 0.74 μm depth resolution is obtained. Then, we introduce the first high-resolution lithium isotopic mapping obtained by LIBS with a 3.3 μm lateral resolution and a typical 40% relative uncertainty on the 6Li isotopic ratio is obtained. Those results could be applied in the future to a large number of solid samples where fast information on the lithium isotopic distribution are needed, for instance in solid-state batteries development.