Andrzej W. Miziolek

Laser-Induced Breakdown Spectroscopy (LIBS): Fundamentals and Applications

Preface R. Russo and A. W. Miziolek 1. History and fundamentals of LIBS D. A. Cremers and L. J. Radziemski 2. Plasma morphology I. Schechter and V. Bulatov 3. From sample to signal in laser induced breakdown spectroscopy: a complex route to quantitative analysis E. Tognoni, V. Palleschi, M. Corsi, G. Cristoforetti, N. Omenetto, I. Gornushkin, B. W. Smith and J. D. Winefordner 4. Laser induced breakdown in gases: experiments and simulation C. G. Parigger 5. Analysis of aerosols by LIBS U. Panne and D. Hahn 6. Chemical imaging of surfaces using LIBS J. M. Vadillo and J. J. Laserna 7. Biomedical applications of LIBS H. H. Telle and O. Samek 8. LIBS for the analysis of pharmaceutical materials. S. Bechard and Y. Mouget 9. Cultural heritage applications of LIBS D. Anglos and J. C. Miller 10. Civilian and military environmental contamination studies using LIBS J. P. Singh, F. Y. Yueh, V. N. Rai, R. Harmon, S. Beaton, P. French, F. C. DeLucia, Jr., B. Peterson, K. L. McNesby and A. W. Miziolek 11. Industrial applications of LIBS R. Noll, V. Sturm, M. Stepputat, A. Whitehouse, J. Young and P. Evans 12. Resonance-enhanced LIBS N. H. Cheung 13. Short-pulse LIBS: fundamentals and applications R. E. Russo 14. High-speed, high resolution LIBS using diode-pumped solid state lasers H. Bette and R. Noll 15. LIBS using sequential laser pulses J. Pender, B. Pearman, J. Scaffidi, S. R. Goode and S. M. Angel 16. Micro LIBS technique P. Fichet, J-L, Lacour, D. Menut, P. Mauchien, A. Rivoallan, C. Fabre, J. Dubessy and M-C. Boiron 17. New spectral detectors for LIBS M. Sabsabi and V. Detalle 18. Spark-induced breakdown spectroscopy: a description of an electrically-generated LIBS-like process for elemental analysis of airborne particulates and solid samples A. J. R. Hunter and L. G. Piper.

Laser-induced breakdown spectroscopy for detection of explosives residues: a review of recent advances, challenges, and future prospects

AbstractIn this review we discuss the application of laser-induced breakdown spectroscopy (LIBS) to the problem of detection of residues of explosives. Research in this area presented in open literature is reviewed. Both laboratory and field-tested standoff LIBS instruments have been used to detect explosive materials. Recent advances in instrumentation and data analysis techniques are discussed, including the use of double-pulse LIBS to reduce air entrainment in the analytical plasma and the application of advanced chemometric techniques such as partial least-squares discriminant analysis to discriminate between residues of explosives and non-explosives on various surfaces. A number of challenges associated with detection of explosives residues using LIBS have been identified, along with their possible solutions. Several groups have investigated methods for improving the sensitivity and selectivity of LIBS for detection of explosives, including the use of femtosecond-pulse lasers, supplemental enhancement of the laser-induced plasma emission, and complementary orthogonal techniques. Despite the associated challenges, researchers have demonstrated the tremendous potential of LIBS for real-time detection of explosives residues at standoff distances. FigureThis review discusses the application of laser-induced breakdown spectroscopy (LIBS) to the problem of explosive residue detection. LIBS offers the capability for real-time, standoff detection of trace amounts of residue explosives on various surfaces

Test of a stand-off laser-induced breakdown spectroscopy sensor for the detection of explosive residues on solid surfaces

The detection and characterization of energetic materials at distances up to 45 m using stand-off laser induced breakdown spectroscopy (LIBS) has been demonstrated. A field-portable open-path LIB spectrometer working under a coaxial configuration was used. A preliminary study allowed choosing a single-pulse laser source over a double-pulse system as the most suitable source for the stand-off analysis of organic samples. The C2 Swan system, as well as the hydrogen, oxygen and nitrogen emission intensity ratios were the necessary parameters to identify the analyte as an organic explosive, organic non-explosive and non-organic samples. O/N intensity ratios of 2.9 and 2.16 with relative standard deviations of 4.03% and 8.36% were obtained for 2,4-dinitrotoluene and aluminium samples, respectively. A field test with known samples and a blind test were carried out at a distance of 30 m from the sample. Identification of energetic compounds in such conditions resulted in 19 correct results out of 21 samples.

Analysis of environmental lead contamination: comparison of LIBS field and laboratory instruments

Abstract The Army Research Office of the Army Research Laboratory recently sponsored the development of a commercial laser-induced breakdown spectroscopy (LIBS) chemical sensor that is sufficiently compact and robust for use in the field. This portable unit was developed primarily for the rapid, non-destructive detection of lead (Pb) in soils and in paint. In order to better characterize the portable system, a comparative study was undertaken in which the performance of the portable system was compared with a laboratory LIBS system at the Army Research Laboratory that employs a much more sophisticated laser and detector. The particular focus of this study was to determine the effects on the performance of the field sensors lower spectral resolution, lack of detector gating, and the multiple laser pulsing that occurs when using a passively Q-switched laser. Surprisingly, both the laboratory and portable LIBS systems exhibited similar performance with regards to detection of Pb in both soils and in paint over the 0.05–1% concentration levels. This implies that for samples similar to those studied here, high-temporal resolution time gating of the detector is not necessary for quantitative analysis by LIBS. It was also observed that the multiple pulsing of the laser did not have a significant positive or negative effect on the measurement of Pb concentrations. The alternative of using other Pb lines besides the strong 406-nm line was also investigated. No other Pb line was superior in strength to the 406-nm line for the latex paint and the type of soils used in the study, although the emission line at 220 nm in the UV portion of the spectrum holds potential for avoiding elemental interferences. These results are very encouraging for the development of lightweight, portable LIBS sensors that use less expensive and less sophisticated laser and detector components. The portable LIBS system was also field tested successfully at sites of documented Pb contamination on military installations in California and Colorado.

Strategies for residue explosives detection using laser-induced breakdown spectroscopy

The ability to detect trace amounts of explosives and their residues in real time is of vital interest to Homeland Security and the military. Previous work at the US Army Research Laboratory (ARL) demonstrated the potential of laser-induced breakdown spectroscopy (LIBS) for the detection of energetic materials. Our recent efforts have been focused on improving the sensitivity and selectivity of LIBS for residue explosives detection and on extending this work to the standoff detection of explosive residues. One difficulty with detecting energetic materials is that the contribution to the oxygen and nitrogen signals from air can impede the identification of the explosive material. Techniques for reducing the air entrainment into the plasma—such as using an argon buffer gas or a collinear double-pulse configuration—have been investigated for this application. In addition to the laboratory studies, ARL’s new double-pulse standoff system (ST-LIBS) has recently been used to detect explosive residues at 20 m. The efficacy of chemometric techniques such as linear correlation, principal components analysis (PCA), and partial least squares discriminant analysis (PLS-DA) for the identification of explosive residues is also discussed. We have shown that despite the typical characterization of LIBS as an elemental technique, the relative elemental intensities in the LIBS spectra are representative of the stoichiometry of the parent molecules and can be used to discriminate materials containing the same elements. Simultaneous biohazard and explosive residue discrimination at standoff distances has also been demonstrated.

Multivariate analysis of standoff laser-induced breakdown spectroscopy spectra for classification of explosive-containing residues

A technique being evaluated for standoff explosives detection is laser-induced breakdown spectroscopy (LIBS). LIBS is a real-time sensor technology that uses components that can be configured into a ruggedized standoff instrument. The U.S. Army Research Laboratory has been coupling standoff LIBS spectra with chemometrics for several years now in order to discriminate between explosives and nonexplosives. We have investigated the use of partial least squares discriminant analysis (PLS-DA) for explosives detection. We have extended our study of PLS-DA to more complex sample types, including binary mixtures, different types of explosives, and samples not included in the model. We demonstrate the importance of building the PLS-DA model by iteratively testing it against sample test sets. Independent test sets are used to test the robustness of the final model.

Laser-induced breakdown spectroscopy (LIBS) – an emerging field-portable sensor technology for real-time, in-situ geochemical and environmental analysis

Laser-induced breakdown spectroscopy (LIBS) is a simple spark spectrochemical sensor technology in which a laser beam is directed at a sample to create a high-temperature microplasma. A spectrometer/array detector is used to disperse the light emission and detect its intensity at specific wavelengths. LIBS has many attributes that make it an attractive tool for chemical analysis. A recent breakthrough in component development, the commercial launching of a small, high-resolution spectrometer, has greatly expanded the utility of LIBS and resulted in a new potential for field-portable broadband LIBS because the technique is now sensitive simultaneously to all chemical elements due to detector response in the 200 to 980 nm range with 0.1 nm spectral resolution. Other attributes include: (a) small size and weight; (b) technologically mature, inherently rugged, and affordable components; (c) in-situ analysis with no sample preparation required; (d) inherent high sensitivity; (e) real-time response; and (f) point sensing or standoff detection. LIBS sensor systems can be used to detect and analyse target samples by identifying all constituent elements and by determining either their relative or absolute abundances.

Standoff Detection of Chemical and Biological Threats Using Laser-Induced Breakdown Spectroscopy:

Laser-induced breakdown spectroscopy (LIBS) is a promising technique for real-time chemical and biological warfare agent detection in the field. We have demonstrated the detection and discrimination of the biological warfare agent surrogates Bacillus subtilis (BG) (2% false negatives, 0% false positives) and ovalbumin (0% false negatives, 1% false positives) at 20 meters using standoff laser-induced breakdown spectroscopy (ST-LIBS) and linear correlation. Unknown interferent samples (not included in the model), samples on different substrates, and mixtures of BG and Arizona road dust have been classified with reasonable success using partial least squares discriminant analysis (PLS-DA). A few of the samples tested such as the soot (not included in the model) and the 25% BG:75% dust mixture resulted in a significant number of false positives or false negatives, respectively. Our preliminary results indicate that while LIBS is able to discriminate biomaterials with similar elemental compositions at standoff distances based on differences in key intensity ratios, further work is needed to reduce the number of false positives/negatives by refining the PLS-DA model to include a sufficient range of material classes and carefully selecting a detection threshold. In addition, we have demonstrated that LIBS can distinguish five different organophosphate nerve agent simulants at 20 meters, despite their similar stoichiometric formulas. Finally, a combined PLS-DA model for chemical, biological, and explosives detection using a single ST-LIBS sensor has been developed in order to demonstrate the potential of standoff LIBS for universal hazardous materials detection.

Laser-induced breakdown spectroscopy (LIBS)

Laser-induced breakdown spectroscopy (LIBS) is an emerging technique for materials analysis that is rapidly maturing and is becoming increasingly accepted as an important tool in analytical chemistry. LIBS is also advancing as a technology as new commercial instruments are becoming available. The core attributes of (1) real-time analysis; (2) no sample preparation; (3) high sensitivity; (4) high specificity for materials identification; (5) sensitivity to all chemical elements in each laser shot; as well as (6) uncommon versatility of point, standoff, as well as underwater-sensing provides a strong argument that LIBS will make a significant impact on science and society. A bibliometric study of the LIBS literature shows clearly that the importance and the number of application areas related to LIBS and laser-based techniques continues to grow. The driving force for this growth appears to be its rapid and remote analysis capabilities for a wide variety of sample types, including the analysis where the requirement for little or no sample preparation is important and the consumption of very small amounts of the sample is critical. Additionally, the relative ease with which LIBS can be combined with other techniques, particularly molecular techniques such as Raman spectroscopy is an advantage. For proof of the impact that LIBS is already making, one needs to go no further than to learn about the next Mission toMars scheduled for 2011/2012 where LIBS is the prime chemical analytical tool of choice. This special issue on LIBS presents the latest progress in this rapidly evolving spectroscopic technique. The 18 articles represent a good balance between fundamental research on the LIBS phenomenology and the applied use of this technique. The papers presented indicate to the reader the active areas in the LIBS field. For example, research is focused on improving the sensitivity of the technique shows that the approach of double-pulse is still of interest. The understanding of physical phenomenon at the early stage of the plasma or the comparison between singleand double-pulse is still attracting further research. While Nd:YAG lasers operating at the fundamental wavelength 1,064 nm or its harmonics are most used for the laser-induced plasma generation in LIBS applications; some papers are focused on the use of the CO2 laser at 10.6 μm. In some cases, the use of this infrared laser may present benefits which can be further exploited. The analysis of slurries is a field of application where LIBS can offer a powerful tool for real-time analysis as the current analytical approaches in this field by conventional This article was published in the special issue Laser-Induced Breakdown Spectroscopy with Guest Editors Jagdish P. Singh, Jose Almirall, Mohamad Sabsabi, and Andrzej Miziolek.

Time-resolved emission studies of ArF-laser-produced microplasmas

ArF-laser-produced microplasmas in CO, CO(2), methanol, and chloroform are studied by time-resolved emission measurements of the plasma decay. Electron densities are deduced from Stark broadening of the line profiles of atomic H, C, O, and Cl. Plasma ionization and excitation temperatures are determined from measurements of relative populations of ionic and neutral species produced in the plasmas. A discussion of the thermodynamic equilibrium status of ArF-laser microplasmas is presented. In general, the ArF-laser-produced microplasma environment is found to be similar in all the gases studied, in terms of both temperature (15,000-20,000 K) and electron density (10(17) cm(-3)-10(18) cm(-3)), despite the considerable differences observed in the breakdown thresholds and relative energies deposited in the various gases.