The first part of this two-part review focused on the fundamental and diagnostics aspects of laser-induced plasmas, only touching briefly upon concepts such as sensitivity and detection limits and largely omitting any discussion of the vast panorama of the practical applications of the technique. Clearly a true LIBS community has emerged, which promises to quicken the pace of LIBS developments, applications, and implementations. With this second part, a more applied flavor is taken, and its intended goal is summarizing the current state-of-the-art of analytical LIBS, providing a contemporary snapshot of LIBS applications, and highlighting new directions in laser-induced breakdown spectroscopy, such as novel approaches, instrumental developments, and advanced use of chemometric tools. More specifically, we discuss instrumental and analytical approaches (e.g., double- and multi-pulse LIBS to improve the sensitivity), calibration-free approaches, hyphenated approaches in which techniques such as Raman and fluorescence are coupled with LIBS to increase sensitivity and information power, resonantly enhanced LIBS approaches, signal processing and optimization (e.g., signal-to-noise analysis), and finally applications. An attempt is made to provide an updated view of the role played by LIBS in the various fields, with emphasis on applications considered to be unique. We finally try to assess where LIBS is going as an analytical field, where in our opinion it should go, and what should still be done for consolidating the technique as a mature method of chemical analysis.

https://journals.sagepub.com/doi/pdf/10.1366/11-06574

Laser-induced breakdown spectroscopy (LIBS), part II: review of instrumental and methodological approaches to material analysis and applications to different fields.

The laser-induced incandescence of a particle of unknown size and composition can be detected simultaneously with the light elastically scattered by the particle, providing information on both the size and composition of the particle. The technique relies on vaporization of the particle; detection of the incandescence signal at the time of vaporization allows determination of the boiling point of the particle, which can in turn be related to the composition of the particle. The elastically scattered signal provides information about the size of the particle and confirmation that it was vaporized. The technique is demonstrated by directing particles through a Nd:YAG laser cavity with ∼106 W/cm2 of circulating intensity. Elements such as tungsten, silicon, and graphite, as well as common aerosols such as soot, can be detected and identified.

Particle identification by laser-induced incandescence in a solid-state laser cavity.

Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications

Flame aerosol synthesis of nanostructured materials and functional devices: Processing, modeling, and diagnostics

The use of laser‐induced breakdown spectrometry (LIBS) has grown steadily, and it has proven to be a relatively dynamic research activity for performing direct spectrochemical elemental or metal analysis of a variety of materials, solids, liquids, and gases, with none or little sample pretreatment procedures. Significant progress has been made during the last several years on the diverse and versatile applications of LIBS including remote material analysis in nuclear power stations, space exploration, diagnostics of archaeological objects, and metal diffusion in solar cells, etc. This review presents the more recent applications of LIBS based on the development of fiber‐optic (FO) technology and portable instrumentation. The characteristics of matrices, object of analysis, laser system used, and analytical performances are tabulated for metallurgical samples, liquid and colloid samples, aerosol and gases, environmental samples, non‐metallic solids, advanced materials, and miscellaneous applications.

Recent Applications of Laser‐Induced Breakdown Spectrometry: A Review of Material Approaches

Laser-induced breakdown spectroscopy (LIBS) has been widely pursued for trace elemental determination in gases, solids, and liquids. Application to liquids has proved problematic due to high spatial confinement of the LIBS plasma and rapid quenching of the excited-state emission. This work presents an alternative approach to trace metal determination in liquids in which 1.0 mL of liquid is deposited onto a carbon planchet and then evaporated, thus transforming the liquid analysis to a solid surface analysis. Using optimized excitation and detection conditions, we have identified spectral regions for sensitive detection of 15 metals (Mg, Al, Si, Ca, Ti, Cr, Fe, Co, Ni, Cu, Zn, As, Cd, Hg, Pb). The limit of detection (LOD) for the technique ranged from 10 ppb to 10 ppm for these elements. A 100 ppb LOD represents detection of 130 picograms of metal (approximately 2 picomoles) in a single measurement calculated from the laser spot size on the sample. Scanning electron microscopy (SEM) images and energy-dispersive X-ray (EDX) spectra of the samples provide insight into the observed reproducibility and linearity of the technique for several of the metals studied.

Trace Metal Detection by Laser-Induced Breakdown Spectroscopy

Laser-induced incandescence is both characterized and demonstrated for the measurement of metal nanoparticle concentration. Reported are the results of an initial characterization of the spectral and temporal signature of the laser-induced incandescence as a function of the excitation laser fluence and wavelength. Validation of the incandescence as a measure of the concentration is demonstrated by absorption measurements. Fluence dependence measurements are also presented. Double-pulse measurements determine the fluence for the onset of vaporization-induced mass loss. Comparisons between the present observations and those for carbon nanostructures are also made. Metals tested include (in order of increasing vaporization temperature) Fe, Ti, Mo, and W.

Laser-induced incandescence applied to metal nanostructures

An alternative approach for laser-induced breakdown spectroscopy (LIBS) determination of trace metal determination in liquids is demonstrated. The limits of detection (LOD) for the technique ranged from 10 ppb to 10 ppm for 15 metals metals (Mg, Al, Si, Ca, Ti, Cr, Fe, Co, Ni, Cu, Zn, As, Cd, Hg, Pb) tested.

/pdf/laser-induced-breakdown-spectroscopy-of-trace-metals-4zhdmlcvsv.pdf

Joseph R. West

Papers

Trace Metal Detection by Laser-Induced Breakdown Spectroscopy

Laser-induced incandescence applied to metal nanostructures

Laser-induced breakdown spectroscopy of trace metals