Quantitative multi-elemental laser-induced breakdown spectroscopy using artificial neural networks

The Laser-Induced Breakdown Spectroscopy (LIBS) is an emerging technique with great potential in atomic elemental analysis in many areas, particularly, in space exploration. In this paper, an algorithm for automated identification of elements and measurements of their concentrations in rocks and soils, as well as its experimental validation are presented. The proposed approach is based on the artificial neural network (ANN). We demonstrate that the ANN algorithm works successfully for all major elements of geological interest tested on natural rock and soil samples

Megapixel multi-elemental imaging by Laser-Induced Breakdown Spectroscopy, a technology with considerable potential for paleoclimate studies

Paleoclimate studies play a crucial role in understanding past and future climates and their environmental impacts. Current methodologies for performing highly sensitive elemental analysis at micrometre spatial resolutions are restricted to the use of complex and/or not easily applied techniques, such as synchrotron radiation X-ray fluorescence micro-analysis (μ-SRXRF), nano secondary ion mass spectrometry (nano-SIMS) or laser ablation inductively coupled plasma mass spectrometry (LAICP-MS). Moreover, the analysis of large samples (>few cm²) with any of these methods remains very challenging due to their relatively low acquisition speed (~1–10 Hz), and because they must be operated in vacuum or controlled atmosphere. In this work, we proposed an imaging methodology based on laser-induced breakdown spectroscopy, to perform fast multi-elemental scanning of large geological samples with high performance in terms of sensitivity (ppm-level), lateral resolution (up to 10 μm) and operating speed (100 Hz). This method was successfully applied to obtain the first megapixel images of large geological samples and yielded new information, not accessible using other techniques. These results open a new perspective into the use of laser spectroscopy in a variety of geochemical applications

LIBS imaging applications

International audienceIn recent years, important developments have been achieved in the application of laser-induced breakdown spectroscopy (LIBS) for elemental imaging. The aim of this chapter is to report recent instrumental configurations and applications related to LIBS-based imaging. In the first section, different instrumental alternatives for LIBS imaging measurements are presented. The second section reports the wide variety of laboratory applications in geological, industrial, and biomedical fields that have benefited from LIBS mapping techniques

Investigation of signal extraction in the frame of laser induced breakdown spectroscopy imaging

International audienceLaser-induced breakdown spectroscopy (LIBS)-based imaging techniques have become well known among spatially resolved elemental approaches due to their mature instrumentation and outstanding advantages and applications. Data processing and in particular signal extraction are key in all LIBS-based imaging analyses to provide robust and reliable results. To date, there has not been a statistical evaluation of this issue when processing large and complex LIBS datasets. In this work, we aimed to test the performance of three extraction methods applied to micro-LIBS-based imaging. We also proposed a new conditional data extraction procedure relying on the statistical uncertainty associated with the extracted signal. We built a synthetic spectral dataset with controlled spectral features and tested the linearity, dynamic range and operating speed of different extraction approaches. The results of this study demonstrate the importance of data extraction and provide evidence for its optimization. This procedure is of particular relevance for the extraction of weak line intensities and in cases where the presence or absence of certain elements is critical (i.e., biomedical applications or trace analysis). In addition, the proposed conditional approach offers new insights into the means of providing LIBS imaging results

Elemental imaging using laser-induced breakdown spectroscopy: A new and promising approach for biological and medical applications

International audienceBiological tissues contain various metal and metalloid ions that play different roles in the structure and function of proteins and are therefore indispensable to several vital biochemical processes. In this review, we discuss the broad capability of laser-induced breakdown spectroscopy (LIBS) for in situ elemental profiling and mapping of metals in biological materials such as plant, animal and human specimens. These biological samples contain or accumulate metal species and metal-containing compounds that can be detected, quantified, and imaged. LIBS enables performing microanalysis, mapping and depth profiling of endogenous and exogenous elements contained in the tissues with a parts-per-million scale sensitivity and microscopic resolution. In addition, this technology generally requires minimal sample preparation. Moreover, its tabletop instrumentation is compatible with optical microscopy and most elements from the periodic table. Specifically, low- and high-atomic-number elements can be detected simultaneously. Recent advances in space-resolved LIBS are reviewed with various examples from vegetable, animal and human specimens. Overall, the performance offered by this new technology along with its ease of operation suggest innumerable applications in biology, such as for the preclinical evaluation of metal-based nanoparticles and in medicine, where it could broaden the horizons of medical diagnostics for all pathologies involving metals

Imaging rare-earth elements in minerals by laser-induced plasma spectroscopy: Molecular emission and plasma-induced luminescence

International audienceLaser-induced breakdown spectroscopy (LIBS) of atoms and ions of rare earth elements (REEs) appears to be an effective tool for REE detection and identification, specifically in imaging applications. We propose to combine this technique with the molecular emissions of LaO and YO and the plasma-induced luminescence (PIL) of REEs in luminescent matrixes. Presently, PIL is mostly sensitive to Eu, Sm, Dy, Gd, and Pr. The main advantage of the proposed technique is that both molecular emission and PIL are characterized by long plasma lifetimes, tens and hundreds of microseconds, when nearly all interfering emissions do not practically exist. Furthermore, the relatively broad emission and luminescence bands and lines enable us to use spectroscopic equipment with a relatively low spectral resolution. It is important to emphasize that the proposed experiments (atomic LIBS, molecular LIBS and PIL) are performed with the same experimental setup and from the same plasma source. Only the detection parameters (spectral range and spectrometer slit, as well as the ICCD gain, delay and width) are modified. As result, imaging of REEs becomes more sensitive and less sophisticated. As an illustration, two imaging experiments are shown to emphasize the high complementarity of these three approaches for the detection of REEs

Characterization of lithium phosphorus oxide thin film libraries by Laser-Induced Breakdown Spectroscopy imaging: A step towards high-throughput quantitative analyses

International audienceElemental analysis is a challenge for the development of High Throughput Experimentation (HTE) on thin film materials, and an even greater one when it comes to screening lithium-containing battery materials. In this regard, Laser-Induced Breakdown Spectroscopy has been evaluated here for the quantitative analysis of lithium in libraries of Li2.3PO3.65 amorphous solid electrolyte films. The LIBS analysis of multiple samples with the same composition, but with thicknesses ranging from 50 to 700 nm, has revealed a linear trend in the intensity ratio of the Li I 610.35 nm and P I 214.91 nm emission lines, opening the way to rapid quantitative analysis of material libraries. The sensitivity of the technique finally allowed the detection of the Li I 670.79 nm emission line for film thicknesses down to 4 nm, corresponding to 0.2% of the ablated volume, or about 0.15 pg of L

Investigation on the material in the plasma phase by high temporally and spectrally resolved emission imaging during pulsed laser ablation in liquid (PLAL) for NPs production and consequent considerations on NPs formation

In this paper experimental temperature and density maps of the laser induced plasma in water during pulsed laser ablation in liquid (PLAL) for the production of metallic nanoparticles (NPs) has been determined. A detection system based on the simultaneous acquisition of two emission images at 515 and 410 nm has been constructed and the obtained images have been processed simultaneously by imaging software. The results of the data analysis show a variation of the temperature between 4000 and 7000 K over the plasma volume. Moreover, by the study of the temperature distribution and of the number densities along the plasma expansion axis it is possible to observe the condensation zone of the plasma where NPs can be formed. Finally, the time associated with the electron processes is estimated and the plasma charging effect on NPs is demonstrated. The set of observations retrieved from these experiments suggests the importance of the plasma phase for the growth of NPs and the necessity of considering the spatial distribution of plasma parameters for the understanding of one of the most important issues of the PLAL process, that is the source of solid material in the plasma phase

Experimental investigation of metal-silicate Germanium isotopic fractionation at equilibrium: insights into early planetary differentiation

International audienceThe process of primitive differentiation and the formation of metallic cores are crucial stages in the evolution of terrestrial planets, the Moon, and asteroids. To better understand this process, specific geochemical tracers such as germanium (Ge) are required. Its moderate siderophile and volatile nature is highly dependent on temperature, pressure, and fO2 conditions [1-3]. Significant variations in Ge isotopes between silicate and metallic phases have been observed on different scales (chondrites, Fe-meteorites, and planetary silicate reservoirs [4-6]), identifying a positive metal-silicate mass-dependent isotopic fractionation of Ge.To quantify metal-silicate Ge fractionation at equilibrium, time-series experiments (from 20mn to 168h) were performed using a piston cylinder apparatus (CRPG-Nancy), with Fe-Ni capsules and »3200 ppm Ge-doped CMAS silicate starting materials, at 1350°C, fO2»IW-2.5, and 1GPa to prevent Ge evaporation. Both hand-separated metal and silicate phases were analyzed for Ge using a combination of bulk (HG-MC-ICP-MS) [4] and in-situ (LA-ICP-MS) techniques. High-resolution (»10µm) multi-element spectral imaging (LIBS) provided a novel and powerful approach for interpreting chemical and isotopic data.The LIBS images revealed that the existence of Ge-rich silicate crystals in some experiments, regardless of duration, leads to a decrease in the bulk Ge content of the solid Fe-Ni capsule, suggesting a preferential compatible behavior of Ge. Preliminary results, in crystal-free experiments, show an increase of Ge content in the metal phase overtime (20mn to 48h), ranging from 307 to 1380 ppm, and of δ74Gemetal, lighter than the CMAS composition, from -5.90±0.03‰ to -1.89±0.08‰ (2σSD), with an isotopic equilibrium attained after 3h. In such closed system, we expect δ74Gesilicate > δ74Gemetal, thus a negative Δ74Gemetal-silicate, as opposed to natural sample observations [4-6]. Forthcoming results on the silicate phase will allow to propose an additional kinetic isotopic fractionation occurring during Ge loss through volatility as planetesimals and planets formed.[1] Kegler and Holzheid, (2011) Eur. J. Mineral. 23, 369-378 [2] Righter et al. (2011) EPSL 304, 379-388 [3] Mare et al. (2020) Chem. Geol. 532, 119306 [4] Luais, B. (2012) Chem. Geol. 334, 295-311 [5] Florin et al. (2020) GCA 269, 270-291 [6] Luais et al. (2021) Golds. Abs. 5818

Characteristics Of Laser-Induced Plasma As A Spectroscopic Light Emission Source

Laser-induced plasma is today a widespread spectroscopic emission source. It can be easily generated using compact and reliable nanosecond pulsed lasers and finds applications in various domains with laser-induced breakdown spectroscopy (LIBS). It is however such a particular medium which is intrinsically a transient and non-point light emitting source. Its timeand space-resolved diagnostics is therefore crucial for its optimized use. In this paper, we review our work on the investigation of the morphology and the evolution of the plasma. Different time scales relevant for the description of the plasma\u27s kinetics and dynamics are covered by suitable techniques. Our results show detailed evolution and transformation of the plasma with high temporal and spatial resolutions. The effects of the laser parameters as well as the background gas are particularly studied. © 2012 American Institute of Physics