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.

■ CONTENTS General Information: Books, Reviews, and Conferences 640 Fundamentals 641 Interaction of Laser Beam with Matter 641 Factors Affecting Laser Ablation and LaserInduced Plasma Formation 642 Influence of Target on the Laser-Induced Plasmas 642 Influence of Laser Parameters on the LaserInduced Plasmas 643 Laser Wavelength (λ) 643 Laser Pulse Duration (τ) 643 Laser Pulse Energy (E) 645 Influence of Ambient Gas on the Laser-Induced Plasmas 645 LIBS Methods 647 Double Pulse LIBS 647 Femtosecond LIBS 651 Resonant LIBS 652 Ranging Approaches 652 Applications 654 Surface Inspection, Depth Profiling, and LIBS Imaging 654 Cultural Heritage 654 Industrial Analysis 655 Environmental Monitoring 656 Biomedical and Pharmaceutical Analysis 658 Security and Forensics 659 Analysis of Liquids and Submerged Solids 660 Space Exploration and Isotopic Analysis 662 Space Exploration 662 Isotopic Analysis 662 Conclusions and Future Outlook 663 Author Information 664 Corresponding Author 664 Notes 664 Biographies 664 Acknowledgments 664 References 664

Laser-induced breakdown spectroscopy.

Nanomaterials, defined as particles ranging from 1 to 100 nm diameter, have become widely utilized because of their unique physicochemical properties. Among those nanoparticles, titanium dioxide (TiO2) is frequently used in the production of paints, paper, plastics, welding rod-coating material, cosmetics, etc. TiO2 is the most commonly used semiconductor photocatalyst. Among the different nanomaterials, it is the most studied. Activated by UV-A irradiation, its photocatalytic properties have been utilized in various applications. A wealth of information on TiO2 photocatalytic in activation of bacteria has been acquired over the last 20 years. Hence, in this review article we have described synthesis methods mainly sol–gel type method like sol–gel method, ultrasonic-assisted sol–gel method, microemulsion method, colloidal synthesis, and also other method are discussed like solvo-thermal method, thermal plasma process, supersonically expanded plasma jet method, induction plasma torch, reactive plasma processing, plasma electrolytic oxidation, hydrolysis method, thermohydrolysis method, coprecipitation method, citrate–nitrate autocombustion method, etc. Also applications of TiO2 like medical applications, environmental application, sensor application, photocatalytic applications, and also its health impact for long-term exposure are discussed.

A review on nano-TiO2 sol–gel type syntheses and its applications

The effect of ambient gas on the expansion dynamics of the plasma generated by laser ablation of an aluminum target has been investigated using frequency doubled radiation from a Q-switched Nd:YAG laser. The diagnostic tools include fast photography of overall visible plume emission using a 2 ns gated intensified charged coupled device and space and time resolved emission spectroscopy using a 50 cm monochromator/spectrograph and photomultiplier tube. The expansion behavior of the plasma was studied with ambient air pressure ranging from 10−6 to 100 Torr. Free expansion, plume splitting and sharpening, hydrodynamic instability, and stagnation of the plume were observed at different pressure levels. Space and time resolved emission spectroscopic studies showed a twin peak distribution for Al and Al+ species at farther distances illustrating plume splitting at pressures higher than 100 mTorr. Combining imaging together with time resolved emission diagnostics, a triple structure of the plume was observed. The expansion of the plume front was compared with various expansion models and found to be generally in good agreement.

/pdf/internal-structure-and-expansion-dynamics-of-laser-ablation-1t02oyg66i.pdf

Internal structure and expansion dynamics of laser ablation plumes into ambient gases

Nanoadsorbents: classification, preparation, and applications (with emphasis on aqueous media).

Optical methods are well-established for trace gas detection in many applications, such as industrial process control or environmental sensing. Consequently, they gain much interest in the discussion of sensing methods for counterterrorism, e.g., the detection of explosives. Explosives as well as their decomposition products possess strong absorption features in the mid-infrared (MIR) spectral region between λ=5 and 11 μm. In this report we present two different laser spectroscopic approaches based on quantum cascade lasers (QCLs) operating at wavelengths around λ=5 and 8 μm, respectively. Stand-off configuration for the remote detection of nitro-based explosives (e.g., trinitrotoluene, TNT) and a fiber coupled sensor device for the detection of triacetone triperoxide (TATP) are discussed.

Potentials and limits of mid-infrared laser spectroscopy for the detection of explosives

Plume dynamics of laser-produced aluminum plasma in ambient nitrogen

Phase transformation in room temperature pulsed laser deposited TiO2 thin films

We report on the pulsed laser ablation of aluminum in the presence of nitrogen gas using a 1.06 μm wavelength of Nd:YAG laser. A prominent band of aluminum nitride corresponding to the (0-0) band of the system belonging to a 3π–3π transition was observed at 507.8 nm. An attempt is made to identify the ionized states of aluminum and nitrogen contributing to formation of the AlN band. AlN films were deposited at room temperature and characterized using x-ray diffraction. A direct correlation between the laser ablated aluminum plasma and the deposited AlN film is reported.

Ashwini Kumar Sharma

Papers

Potentials and limits of mid-infrared laser spectroscopy for the detection of explosives

Plume dynamics of laser-produced aluminum plasma in ambient nitrogen

Phase transformation in room temperature pulsed laser deposited TiO2 thin films

Pulsed laser ablation of aluminum in the presence of nitrogen: Formation of aluminum nitride

Spectroscopic investigations of carious tooth decay