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.

Laser-induced breakdown spectroscopy (LIBS) has become a very popular analytical method in the last decade in view of some of its unique features such as applicability to any type of sample, practically no sample preparation, remote sensing capability, and speed of analysis The technique has a remarkably wide applicability in many fields, and the number of applications is still growing From an analytical point of view, the quantitative aspects of LIBS may be considered its Achilles' heel, first due to the complex nature of the laser–sample interaction processes, which depend upon both the laser characteristics and the sample material properties, and second due to the plasma–particle interaction processes, which are space and time dependent Together, these may cause undesirable matrix effects Ways of alleviating these problems rely upon the description of the plasma excitation-ionization processes through the use of classical equilibrium relations and therefore on the assumption that the laser-induced 

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma–Particle Interactions: Still-Challenging Issues Within the Analytical Plasma Community

Laser ablation synthesis in liquid solution (LASiS) is a “green” technique that gives access to the preparation of a library of nanomaterials. Bare noble metal spherical particles, multiphase core–shell oxides, metal–semiconductor heterostructures, layered organometallic compounds and other complex nanostructures can be obtained with the same experimental set up, just by varying a few synthetic parameters. How to govern such versatility is one of the current challenges of LASiS and requires a thorough understanding of the physical and chemical processes involved in the synthesis. In this perspective, the fundamental mechanisms of laser ablation in liquids are summarized, organized according to their temporal sequence and correlated with relevant examples taken from the library of nanomaterials disclosed by LASiS, in order to show how synthesis parameters influence the composition and the structure of products. The resulting framework suggests that, to date, much attention has been devoted to the physical aspects of laser–matter interaction and to the characterization of the final products of the synthesis. Conversely, the clarification of chemical processes active during LASiS deserves more research efforts and requires the synergy among multiple investigation techniques.

What controls the composition and the structure of nanomaterials generated by laser ablation in liquid solution

https://digital.library.unt.edu/ark:/67531/metadc780990/m2/1/high_res_d/861115.pdf

Laser ablation in analytical chemistry - A review

Characterization of laser induced plasmas by optical emission spectroscopy: A review of experiments and methods

In 2002, we wrote an Analytical Chemistry feature article describing the Physics of Laser Ablation in Microchemical Analysis. In line with the theme of the 2002 article, this manuscript discusses current issues in fundamental research, applications based on detecting photons at the ablation site (LIBS and LAMIS) and by collecting particles for excitation in a secondary source (ICP), and directions for the technology.

http://pubs.acs.org/doi/pdf/10.1021/ac4005327

Laser ablation in analytical chemistry.

The craters resulting from high-irradiance (1×109–1×1011 W/cm2) single-pulse laser ablation of single-crystal silicon show a dramatic increase in volume at a threshold irradiance of 2.2×1010 W/CM2. Time-resolved shadowgraph images show ejection of large particulates from the sample above this threshold irradiance, with a time delay ∼300 ns. A numerical model was used to estimate the thickness of a superheated layer near the critical state. Considering the transformation of liquid metal into liquid dielectric near the critical state (i.e., induced transparency), the calculated thickness of the superheated layer at a delay time of 200–300 ns agreed with the measured crater depths. This agreement suggests that induced transparency promotes the formation of a deep superheated layer, and explosive boiling within this layer leads to particulate ejection from the sample.

Evidence for phase-explosion and generation of large particles during high power nanosecond laser ablation of silicon

Early phase laser induced plasma diagnostics and mass removal during single-pulse laser ablation of silicon

The relation between laser-generated particles and ICPMS signal intensity was investigated using single-pulse laser ablation sampling of solids. The particle size distribution of glass samples was measured using an optical particle counter for different laser ablation conditions. Ablation of a new surface produced fewer particles and lower ICPMS signal intensity than a preablated surface. Laser power density of 0.4−0.5 GW/cm2 was found to be a threshold value, across which particle size distribution changed. Laser beam diameter was a more influential parameter than power density in efficient particle generation. Particle loss during transport from the ablation chamber to the ICPMS was significant for a low carrier gas flow rate of 0.1 L/min, while almost no loss was observed for a higher flow rate of 0.26 L/min. The onset of ICPMS intensity time profiles decreased as more large particles were generated. ICPMS intensity data were calibrated with respect to the particle mass entering the ICPMS. Particle ent...

Effects of Particle Size Distribution on Inductively Coupled Plasma Mass Spectrometry Signal Intensity during Laser Ablation of Glass Samples

An overview of laser plasma spectrochemistry is presented to demonstrate its wide range of capabilities. Laser plasmas offer the ability to perform elemental, isotopic, molecular, quantitative and qualitative sample analysis with sub-micron spatial resolution, and each feature can be measured at standoff distances. Obviously, these attributes are not all achievable at the same time, but they can be optimized for specific applications. This manuscript gives a sampling (pun intended) of the research in our group that has demonstrated each of these capabilities. Although the technology is commonly referred to as LIBS (laser-induced breakdown spectroscopy), the authors prefer to use laser plasma spectrometry to represent the underlying science.

Jong Yoo

Papers

Laser ablation in analytical chemistry.

Evidence for phase-explosion and generation of large particles during high power nanosecond laser ablation of silicon

Early phase laser induced plasma diagnostics and mass removal during single-pulse laser ablation of silicon

Effects of Particle Size Distribution on Inductively Coupled Plasma Mass Spectrometry Signal Intensity during Laser Ablation of Glass Samples

Laser plasma spectrochemistry