Laser-induced Breakdown Spectroscopy Experiments Research Articles

Data Science Meets Mineral Analysis: An Innovative Laser-Induced Breakdown Spectroscopy Experiment for Undergraduate Chemistry Students

Data Science Meets Mineral Analysis: An Innovative Laser-Induced Breakdown Spectroscopy Experiment for Undergraduate Chemistry Students

Effect of Femtosecond Ultraviolet and Infrared Laser Wavelength on Plasma Characteristics of Metals, Ceramics and Glass Samples Using Femtosecond Laser-Induced Breakdown Spectroscopy.

In this work, we present studies on the effect of laser wavelengths on the laser-induced plasma characterization using a femtosecond (fs) ytterbium-doped potassium-gadolinium tungstate (Yb:KGW) laser. Plasma plumes of copper, steel, ceramics, and glass samples were induced using a multiple shot of 200 fs laser pulses with 1030 nm and 343 nm wavelengths at fixed laser fluence () and analyzed using the laser-induced breakdown spectroscopy (LIBS) technique. Time-resolved fs-LIBS measurements were performed on the same set of samples and under the same experimental conditions. For the calculation of plasma parameters, the set of spectral lines of Cu(I) (for copper sample), Fe(I) (for steel sample), and Ca(I), K(I) (for glass and ceramics samples) were observed. The plasma electron temperature and density were evaluated from the Boltzmann plots and Stark-broadening profiles of the plasma spectral lines, assuming the local thermodynamic equilibrium condition. Time-resolved plasma temperature and electron density for fs-LIBS using ultraviolet (UV) and infrared (IR) laser wavelengths were analyzed and no significant dependence on fs laser wavelength was observed for any of the samples. However, for all samples the signal-to-noise ratio (SNR) significantly increased using UV laser radiation: copper (), steel (), glass (), and ceramics (). Therefore, by using a fs UV laser wavelength for laser-induced breakdown spectroscopy experiments, for certain materials the SNR and at the same time the limit of detection can be significantly enhanced.

Self-Calibrated Laser-Induced Breakdown Spectroscopy for the Quantitative Elemental Analysis of Suspended Volcanic Ash.

Real-time analysis of fine ash in volcanic plumes, which represent magma fragments expelled from the crater during explosive eruptions, is a valuable tool for volcano monitoring and hazard assessment. To obtain the chemical characterization of the juvenile pyroclastic material emitted in volcanic plumes, many analytical techniques can be used. Among them, laser-induced breakdown spectroscopy (LIBS) is the one that can most easily be adapted to advanced applications in extreme environments. In this paper, LIBS experiments based on self-calibrated approaches are used to determine the elemental composition of suspended volcanic ash. To simulate the conditions of dispersed volcanic ash in the atmosphere, different sizes of volcanic ash samples are suspended in the air by laser-induced shockwaves in a dedicated chamber, and a parametric study is carried out to establish the optimal experimental conditions for recording usable plasma emission spectra for each ash size. The quantitative analysis is performed using a self-calibrated analytical method, including calibration-free LIBS, which is based on the calculation of the spectral radiance of a uniform plasma in local thermodynamic equilibrium. The method accounts intrinsically for self-absorption since it modifies the intensity of spectral lines and thus leads to an underestimation of the elemental fraction. An intensity calibration of the spectra based on the measurements of Fe lines intensities was also used in this work to deduce the apparatus response from the spectrum itself and avoid the use of standard calibration lamps. Results demonstrate the potential of real-time measurements of elemental fractions in volcanic ash with good agreement with the literature composition.

A new method for calibration-free analysis by Laser-Induced Breakdown Spectroscopy using a time-integrated spectrometer

In this paper, we will discuss a new method for obtaining information about the plasma temporal evolution in Laser-Induced Breakdown Spectroscopy (LIBS) experiments using a time-integrated spectrometer.The method, inspired to the Bredice 3D-Boltzmann plot formalism, allows a precise determination of the temporal evolution of the emission line intensity in a LIBS plasma, starting from a series of time-integrated measurements obtained at different delay times after the laser pulse.In this way the application of a calibration-free algorithm using a time-integrated spectrometer is made possible.Examples of the application of the method are given in the analysis of two Zamac (a zinc alloy containing aluminum, magnesium, and copper) certified samples. A good agreement is obtained between the calculated and nominal concentrations of the two samples.A further validation of the method was performed on a third Zamac sample, of unknown composition. The sample was first characterized using a conventional CF-LIBS approach on a time-resolved spectrum; the obtained composition was then compared with the one determined using the series of time-integrated spectra.

Determination of inorganic and organic carbons in a Martian soil simulant under the Martian CO2 atmosphere using LIBS coupled with machine learning

Carbon plays a crucial role in the search for extraterrestrial life and serves as an indicator for the habitability and the paleoatmospheric CO2 reservoir on Mars. Previous exploration missions provided evidence of carbon on Mars with different chemical speciation using various instruments including laser-induced breakdown spectroscopy (LIBS). Quantitative determination with LIBS onboard Mars rovers is still precluded because of the important contribution of the atmospheric carbon in the LIBS plasma, in addition to matrix effects omnipresent for elemental determination with LIBS of geological materials. In this work, we performed a series of LIBS experiments in a simulated Martian atmosphere using samples prepared with a Martian soil simulant mixed with various carbonates and organic C-bearing materials. Convoluted influences on LIBS spectra due to the ambient gas and the different chemical speciation of carbon were observed for inorganic and organic C-bearing materials, which explains the unsatisfactory performance for a univariate regression model based on a carbon-related emission line. In particular, the influence of ambient gas was observed more important for inorganic carbon brought into the samples with carbonates. Multivariate models were then developed based on a back-propagation neural network (BPNN), for ensembles of samples with inorganic and organic carbons respectively, and then for the fusion of the two ensembles. The results showed respective limits of detection (LODs) of 0.247 wt%, 1.022 wt% and 0.873 wt%, and respective root mean square errors of prediction (RMSEPs) of 0.036 wt%, 0.133 wt%, and 0.062 wt% for the three collections of samples. Moreover, the model training process is investigated in detail in order to understand the way in which the most significant spectral features are selected, processed and mapped to the carbon concentrations of the samples by a neural network.

Laser-Induced Plasmas of Plutonium Dioxide in a Double-Walled Cell.

Plutonium research has been stifled by the significant number of administrative controls and safety procedures, space and instrumentation limitations in radiological gloveboxes, and the potential for personnel and equipment contamination. To address the limited number of spectroscopic studies in Pu-bearing compounds in the current scientific literature, this work presents the use of double-walled cells (DWCs) in "clean" buildings/laboratories as an alternative to research in radiological gloveboxes. This study reports the first laser-induced breakdown spectroscopy (LIBS) experiments of a PuO2 pellet contained within a DWC, where the formation of elemental (atomic and ionic) species as well as the evolution from elemental to molecular products (PuxOy) was measured. Raman spectroscopy was also used to characterize the surface of the ablated pellet and the particulates deposited on the window of the inner cell. The full width half-maximum of the T2g band enabled us to obtain an estimate of the temperature at the pellet surface after the ablation pulse and the particulates based on the crystal lattice disorder. Particulates deposited on the window of the DWC during laser ablation were characterized using scanning electron microscopy, where molten irregular particulates and spheroids were observed. This exciting research conducted in a DWC describes our initial attempts to incorporate LIBS in the arsenal of spectroscopic tools for nuclear forensics applications.

Laser-Induced breakdown spectroscopy and Energy-Dispersive X-ray analyses for green mineral fluorite (CaF2)

Laser-induced breakdown spectroscopy (LIBS) technique was utilized to investigate the green mineral fluorite (CaF2) samples. The LIBS experiment was implemented by using Nd: YAG Laser system and a linear array CCD detector coupled with an Avantes spectrometer in an air atmosphere. The emission spectra of ten various fluorite samples were studied. The molecular bands correspond to the green B2Σ+-X2Σ+ and orange A2Π-X2Σ systems of diatomic CaF-molecule, specifically at Δν = -1, 0, +1 sequences and the CaO diatomic molecule between 618 nm and 630 nm were detected. It was observed that the CaF-diatomic molecular emission bands exhibited stronger optical emission compared to the fluorine (F) atomic lines. Chemical composition (wt.%) analysis was acquired using CF-LIBS methodology under optically thin and local thermodynamic equilibrium (LTE) conditions. Our CF-LIBS studies revealed that Ca (50–60%) and F (30–40%) were the major elements, while C (3–5%) and O (2–5%) were minor elements present in all samples. For comparison, we employed energy-dispersive X-ray (EDX) technique to study the essential elemental composition (wt.%). The results achieved from CF-LIBS were found to be in good agreement to that obtained from the EDX technique. To validate CF-LIBS results, the calibration curve method was employed using the validated samples (S3, S5, and S7). Furthermore, we utilized a principal component analysis (PCA) technique on the LIBS spectral data to classify the fluorite samples.

Construction, Spectral Modeling, Parameter Inversion-Based Calibration, and Application of an Echelle Spectrometer.

We have developed a compact, asymmetric three-channel echelle spectrometer with remarkable high-spectral resolution capabilities. In order to achieve the desired spectral resolution, we initially establish a theoretical spectral model based on the two-dimensional coordinates of spot positions corresponding to each wavelength. Next, we present an innovative and refined method for precisely calibrating echelle spectrometers through parameter inversion. Our analysis delves into the complexities of the nonlinear two-dimensional echelle spectrogram. We employ a variety of optimization techniques, such as grid exploration, simulated annealing, genetic algorithms, and genetic simulated annealing (GSA) algorithms, to accurately invert spectrogram parameters. Our proposed GSA algorithm synergistically integrates the strengths of global and local searches, thereby enhancing calibration accuracy. Compared to the conventional grid exploration method, GSA reduces the error function by 22.8%, convergence time by 2.16 times, and calibration accuracy by 7.05 times. Experimental validation involves calibrating a low-pressure mercury lamp, resulting in an average spectral accuracy error of 0.0257 nm after performing crucial parameter inversion. Furthermore, the echelle spectrometer undergoes a laser-induced breakdown spectroscopy experiment, demonstrating exceptional spectral resolution and sub-10 ns time-resolved capability. Overall, our research offers a comprehensive and efficient solution for constructing, modeling, calibrating, and applying echelle spectrometers, significantly enhancing calibration accuracy and efficiency. This work contributes to the advancement of spectrometry and opens up new possibilities for high-resolution spectral analysis across various research and industry domains.

Study on the radiation and self-absorption characteristics of plasma under various background gases.

The self-absorption effect is a primary factor responsible for the decline in the precision of quantitative analysis techniques using plasma emission spectroscopy, such as laser-induced breakdown spectroscopy (LIBS). In this study, based on the thermal ablation and hydrodynamics models, the radiation characteristics and self-absorption of laser-induced plasmas under different background gases were theoretically simulated and experimentally verified to investigate ways of weakening the self-absorption effect in plasma. The results reveal that the plasma temperature and density increase with higher molecular weight and pressure of the background gas, leading to stronger species emission line intensity. To reduce the self-absorption effect in the later stages of plasma evolution, we can decrease the gas pressure or substitute the background gas with a lower molecular weight. As the excitation energy of the species increases, the impact of the background gas type on the spectral line intensity becomes more pronounced. Moreover, we accurately calculated the optically thin moments under various conditions using theoretical models, which are consistent with the experimental results. From the temporal evolution of the doublet intensity ratio of species, it is deduced that the optically thin moment appears later with higher molecular weight and pressure of the background gas and lower upper energy of the species. This theoretical research is essential in selecting the appropriate background gas type and pressure and doublets in self-absorption-free LIBS (SAF-LIBS) experiments to weaken the self-absorption effect.

Effect of laser ablation angles on the ablated depth/mass and spectral intensity of laser-induced plasma on EAST-like plasma-facing materials in a vacuum

Real-time acquisition of the dynamic information on the surface elemental composition of the first wall, especially in the divertor region, is of great significance for understanding the plasma-wall interaction (PWI) process and optimizing the experimental conditions of the tokamak. The effect of laser ablation angles (LAAs) needs to be further evaluated for the in-situ laser-induced breakdown spectroscopy (LIBS) system on the EAST upper divertor that is being upgraded. LIBS experiments with a coaxial collection configuration were carried out at 1 × 10−5 mbar in the laboratory and over a wide range of LAAs from 0° to 72°. Tungsten (W), molybdenum (Mo), and copper (Cu) which are important plasma-facing materials in EAST were ablated under variable LAAs. Their ablation depth and ablation mass were measured by confocal microscopy. The depth ablation rate show that the larger the LAAs, the higher the depth resolution of LIBS, which is helpful for the depth-profiling analysis of the wall surface. The number of photons at the characteristic spectral line radiated from the three elements at a certain solid angle were obtained by using the absolute calibration method. The variation trend of the photon numbers with the increase of LAAs is consistent with ablation mass but slower than the downward trend of laser power density. By analyzing the variation of the spot size, the spatial intensity distribution of the laser, and the ablation crater morphology caused by the LAAs, it is found that the lateral ablation of the laser is the possible reason for the difference. Moreover, the calibration coefficient of spectral intensity under variable LAAs is obtained, which provides a reference for in-situ LIBS measurement.

Soil texture identification using LIBS data combined with machine learning algorithm

A machine learning based model is developed to classify the soil texture [Clay, Sandy clay (SC), Sandy clay loam (SCL), Sandy loam (SL) and Sand]. The model utilizes the data obtained with Laser Induced Breakdown Spectroscopy (LIBS) method. An investigation on LIBS experiment with and without black slit placed on the top of the soil surface is carried out to determine the appropriate input data format for the model. The considered input formats are raw spectrum, relative intensity (Iλ/I393nm) and relative intensity (Iλ/I553nm). The selection of I553nm as reference line during the computation of relative intensity results in projecting the reflection phenomenon at other wavelengths. Also the reflection from the soil surface is highly dependent on incident plasma emission wavelength and soil texture. The Principle Component Analysis (PCA) method is used to explore the classification power of the input data format. The input data formats are given to machine learning classifiers such as k- Nearest Neighbor (k-NN), Support Vector Machine (SVM), Decision Tree (DT), Random Forest (RB) and Naïve Bayes (NB). From the experimental analysis, it is observed that the Naïve Bayes classifier achieved higher F1-score (Clay = 0.93, SC = 1.00, SCL = 0.86, SL = 0.85 and Sand = 1.00), when it is subjected with Iλ/I553nm data format. This improvement in performance metric is mainly attributed to the consideration of plasma reflection phenomenon at longer wavelength.

Experimental study and simulation of the reaction mechanism of Al-PTFE mechanically activated energetic composites.

In order to explore the mechanism of reaction involving Al-polytetrafluoroethylene (PTFE) mechanically activated energetic composites, a molecular dynamics simulation was carried out to predict the pyrolysis of PTFE. Then, density functional theory (DFT) was applied to calculate the mechanism of reaction between the products of PTFE pyrolysis and Al. Furthermore, the pressure and temperature obtained during the reaction of Al-PTFE were tested to study the chemical structure before and after heating. Finally, the laser-induced breakdown spectroscopy experiment was performed. According to the experimental results, the main pyrolysis products of PTFE include F, CF, CF2, CF3 and C. The path of the CF3 + Al → CF2 + AlF reaction is the easiest to achieve. AlF3, Al and Al2O3 are the main components of the pyrolysis products of PTFE with Al. Compared with Al-PTFE, the ignition temperature required by the Al-PTFE mechanically activated energetic composite is lower and its combustion reaction is faster.

Combination of laser-induced breakdown spectroscopy, and time–of–flight mass spectrometry for the quantification of CoCrFeNiMo high entropy alloys

In this paper, we present the preparation and quantification of the CoCrFeNiMo high entropy alloys that are commonly used in self-propelled stainless steel fabrication, shipbuilding, and other defense industries. Four samples of high entropy alloys, Mo (68.03–77.29%)-Cr (5.24–7.37%)-Fe (5.63–7.92%)-Ni (5.91–8.32%)-Co (5.93–8.36%) were prepared using a standard technique. The as-prepared samples have been quantified by combining Laser-Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Time–of–Flight Mass Spectrometer (LA–TOF–MS) techniques. The LIBS experiments were performed using the second harmonic of a Nd: YAG laser at 532 nm, 100 mJ laser pulse energy, and 5 ns pulse duration, and the emission spectra were registered in the wavelength range from 250 to 870 nm using a set of four miniature spectrometers. It is endorsed that the calibration-free LIBS (CF–LIBS) and the Calibration Curve–Laser-Induced Breakdown Spectroscopy (CC–LIBS) techniques yield the elemental compositions at par with that determined by the LA–TOF–MS, and EDX techniques.

Pressure Effects on Simultaneous Optical and Acoustics Data from Laser-Induced Plasmas in Air: Implications to the Differentiation of Geological Materials.

The shockwave generated alongside the plasma is an intimately linked, yet often neglected additional input for the characterization of solid samples by laser-induced breakdown spectroscopy (LIBS). The present work introduces a dual LIBS-acoustics sensor that takes advantage of the analysis of the acoustic spectrum yielded by shockwaves produced on different geological samples to enhance the discrimination power of LIBS in materials featuring similar optical emission spectra. Six iron-based minerals were tested at a distance of 2 m using 1064 nm laser light and under pressure values ranging from 7 to 1015 mbar. These experimental parameters were selected to assess the effects of pressure, one of the main factors conditioning the propagation of sound as well as a commonly investigated influence in LIBS experiments. Moreover, precise values for carrying out the analyses were set based on one of the most exciting scenarios in which LIBS data may be enhanced by laser-induced acoustics: space exploration. This is exemplified by the tasks performed by the Mars 2020 SuperCam instrument located onboard the Perseverance rover. Authors evaluated the use of acoustic signals both in the time-domain and frequency-domain in sensitive cases for the distinguishing of minerals exhibiting LIBS spectra featuring almost the same emission lines using PCA schemes for each pressure setting. Thus, we report herein the impact of the surrounding pressure level upon this diagnostic tool. Overall, this paper seeks to show how the analytical potential of simultaneous phenomena taking place during a laser-produced plasma event is subjected to the defined operational conditions.

Effect of buffer gas on the analysis of Dunhuang murals by laser-induced breakdown spectroscopy technology

• Damage of laser ablation can be minimized in the buffer gas condition of Helium, while the quality of LIBS spectra was improved. • Buffer gas jet was supplied in open atmosphere through a high-pressure gas cylinder instead of a vacuum target chamber, is more suitable for in-situ analysis. • The strategies performed in this work can also applied in other cultural heritage for the purpose of reducing LIBS damage. In this work, the potential of laser-induced breakdown spectroscopy (LIBS) on micro-destructive analysis of mural pigmented layers was studied under different buffer gases of air, Ar, N 2 , O 2 and He. In order to maintain the intrinsic advantages of LIBS for in-situ analysis, the buffer gas jet was supplied in open atmosphere through a high-pressure gas cylinder instead of a vacuum target chamber. Three kinds of red pigments, cinnabar, red lead, and red ochre that were widely used in Dunhuang murals, were utilized to prepare “mock-up” blocks. The effects of buffer gas on pigment discoloration, ablated crater, intensity of emission signal, signal-to-noise ratio (SNR) and stability of emission signal were studied. For practical application, the flow rates of buffer gas were optimized. It was found that the diameter of the ablated crater is the largest, the pigment discoloration around the crater is more serious in air after laser ablation, followed by Ar, N 2 , and O 2 . On the contrary, in buffer gas of He, these effects are the smallest. Moreover, Ar can enhance radiation of plasma to produce the strongest intensities of spectra, and He is the best choice for obtaining the best SNR and spectral stability among these buffer gases. The optimal gas flow rate for reducing damage and improving LIBS signal is around 5000cm 3 /min. In addition, the influence mechanism of different buffer gases on plasma was discussed qualitatively by combining the physical properties and plasma temperature. Finally, the buffer gas He was applied to analyze the actual mural fragments, and it was conclusively confirmed that He can reduce the damage to the pigment layer and the discoloration caused by high temperature in LIBS experiment.

A Laser-Induced Breakdown Spectroscopy Experiment Platform for High-Degree Simulation of MarSCoDe In Situ Detection on Mars

The Zhurong rover of China’s Tianwen-1 mission started its inspection tour on Mars in May 2021. As a major scientific payload onboard the Zhurong rover, the Mars Surface Composition Detector (MarSCoDe) instrument adopts laser-induced breakdown spectroscopy (LIBS) to detect and analyze the chemical composition of Martian materials. This paper introduces an experimental platform capable of establishing a simulated Martian atmospheric environment, in which a duplicate model of the MarSCoDe flight model is placed. In the simulated environment, the limit vacuum degree can reach 10−5 Pa level, the temperature can change from −190 °C to +180 °C, and different gases can be filled and mixed according to desired proportion. Moreover, the sample stage can move along a track inside the vacuum chamber, enabling the detection distance to vary from 1.5 m to 7 m. Preliminary experimental results indicate that this platform is able to simulate the scenario of MarSCoDe in situ LIBS detection on Mars well.

Monitoring of tritium and impurities in the first wall of fusion devices using a LIBS based diagnostic

Laser-induced breakdown spectroscopy (LIBS) is one of the most promising methods for quantitative in-situ determination of fuel retention in plasma-facing components (PFCs) of magnetically confined fusion devices like ITER and JET. In this article, the current state of understanding in LIBS development for fusion applications will be presented, based on a complete review of existing results and complemented with newly obtained data. The work has been performed as part of a research programme, set up in the EUROfusion Consortium, to address the main requirements for ITER: (a) quantification of fuel from relevant surfaces with high sensitivity, (b) the technical demonstration to perform LIBS with a remote handling system and (c) accurate detection of fuel at ambient pressures relevant for ITER. For the first goal, the elemental composition of ITER-like deposits and proxies to them, including deuterium (D) or helium (He) containing W–Be, W, W–Al and Be–O–C coatings, was successfully determined with a typical depth resolution ranging from 50 up to 250 nm per laser pulse. Deuterium was used as a substitute for tritium (T) and in the LIBS experiments deuterium surface densities below 1016 D/cm2 could be measured with an accuracy of ∼30%, confirming the required high sensitivity for fuel-retention investigations. The performance of different LIBS configurations was explored, comprising LIBS systems based on single pulse (pulse durations: ps–ns) and double pulse lasers with different pulse durations. For the second goal, a remote handling application was demonstrated inside the Frascati-Tokamak-Upgrade (FTU), where a compact, remotely controlled LIBS system was mounted on a multipurpose deployer providing an in-vessel retention monitor system. During a shutdown phase, LIBS was performed at atmospheric pressure, for measuring the composition and fuel content of different area of the stainless-steel FTU first wall, and the titanium zirconium molybdenum alloy tiles of the toroidal limiter. These achievements underline the capability of a LIBS-based retention monitor, which complies with the requirements for JET and ITER operating in DT with a beryllium wall and a tungsten divertor. Concerning the capabilities of LIBS at pressure conditions relevant for ITER, quantitative determination of the composition of PFC materials at ambient pressures up to 100 mbar of N2, the D content could be determined with an accuracy of 25%, while for atmospheric pressure conditions, an accuracy of about 50% was found when using single-pulse lasers. To improve the LIBS performance in atmospheric pressure conditions, a novel approach is proposed for quantitative determination of the retained T and the D/T ratio. This scenario is based on measuring the LIBS plume emission at two different time delays after each laser pulse. On virtue of application of a double pulse LIBS system, for LIBS application at N2 atmospheric pressure the distinguishability of the spectra from H isotopes could be significantly improved, but further systematic research is required.

Accurate identification of soluble solid content in citrus by indirect laser-induced breakdown spectroscopy with its leaves

The soluble solid content (SSC) is vital to distinguish citrus quality, and non-destructive detection on site in the identification of SSC for citrus is urgently demanded. In this paper, a new approach was proposed to accurately identify citrus’s SSC using indirect laser-induced breakdown spectroscopy (LIBS) with its leaves. Forty-five Ehime Kashi No.28 citruses with surrounding leaves picked at two different times were prepared for LIBS experiment. The genetic algorithm-support vector machine model had the best identification result with cross-validation set accuracy of 91.2% and the prediction set accuracy of 92.03%. Furthermore, the influence of element in citrus leaves on SSC identification was analyzed by one-way analysis of variance, which showed that magnesium in citrus leaves was notably related to SSC due to its participation in photosynthesis and carbohydrates transportation. All in all, the results demonstrated that the indirect LIBS with citrus leaves could be a non-destructive and reliable approach for accurate identification of citrus SSC on spot.

The use of a digital micromirror array as a temporal gate and spatial-filtering device for laser-induced breakdown spectroscopy and laser ablation molecular isotopic spectrometry

A digital micromirror array (DMMA) is used in a simple and inexpensive approach for spatially resolved temporal gating of atomic emission detection in laser-induced breakdown spectroscopy (LIBS). Selected mirrors in the array are actuated at a time delayed from the primary laser pulse, permitting optical gating with a response time of 160 ns while using a conventional CCD detector. Detector gating is shown to decrease noise from short-lived spectroscopic background (both continuum and N II from air), improving signal-to-background ratios by 22-times for selected samples and emission lines. The utility of rapid temporal gating is also demonstrated for the optical detection of isotopes using the laser-ablation molecular isotope spectrometry (LAMIS) experiment. Optical temporal gating and spatial filtering are used to isolate regions of the laser-induced plasma, enhancing signal from molecular emission. The potential of the simple technique for use in field-portable LIBS and LAMIS experiments is explored.

Methodology for the Implementation of Internal Standard to Laser-Induced Breakdown Spectroscopy Analysis of Soft Tissues.

The improving performance of the laser-induced breakdown spectroscopy (LIBS) triggered its utilization in the challenging topic of soft tissue analysis. Alterations of elemental content within soft tissues are commonly assessed and provide further insights in biological research. However, the laser ablation of soft tissues is a complex issue and demands a priori optimization, which is not straightforward in respect to a typical LIBS experiment. Here, we focus on implementing an internal standard into the LIBS elemental analysis of soft tissue samples. We achieve this by extending routine methodology for optimization of soft tissues analysis with a standard spiking method. This step enables a robust optimization procedure of LIBS experimental settings. Considering the implementation of LIBS analysis to the histological routine, we avoid further alterations of the tissue structure. Therefore, we propose a unique methodology of sample preparation, analysis, and subsequent data treatment, which enables the comparison of signal response from heterogenous matrix for different LIBS parameters. Additionally, a brief step-by-step process of optimization to achieve the highest signal-to-noise ratio (SNR) is described. The quality of laser–tissue interaction is investigated on the basis of the zinc signal response, while selected experimental parameters (e.g., defocus, gate delay, laser energy, and ambient atmosphere) are systematically modified.