LIBS spectroscopy meets the ocean. Chemical analysis of archeological materials in Mediterranean waters

After decades of development in laboratories and land operations, chemical analysis of submerged objects is starting to become a reality. While the analysis of water at variable depth has been demonstrated in the past using florescence spectroscopy and Raman spectroscopy, determination of the atomic composition of submerged objects is much a more complex task. Technology based on laser-induced breakdown spectroscopy (LIBS) has been recently developed for such sub-sea operations. This paper will discuss the operating parameters of a marine LIBS analyzer. Metals, alloys, rocks, marble, concrete, can be analyzed at a depth of up to 50 m. The system has been tested in several coastal surveys in Mediterranean waters.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

LIBS detection of atoms and molecules in nanoplasmas of levitated particles

Single particle characterization still constitutes a challenge to contemporary chemical analysis. Considerable effort worldwide is being devoted to conceive experimental strategies providing detection capabilities compatible with the extremely low mass of micro- and nano-particles and the ability to determine the chemical composition of the individual entities. The notion of using optical levitation to trap individual particles was demonstrated in the past century. Recently we have proposed the multielemental analysis of individual nanoparticles in optical traps using LIBS. In this lecture, the fundamentals of optical trapping of nanoparticles in air will be presented. The specific excitation and ionization processes leading to efficient optical detection and an analysis of the photon emission efficiency will be discussed. Finally, some limiting factors involved in our approach and prospective directions for improvement will be presentedUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Multielemental analysis in nanoplasmas of isolated particles in an optical trap

Single particle characterization still constitutes a challenge to contemporary chemical analysis. Considerable effort worldwide is being devoted to conceive experimental strategies providing detection capabilities compatible with the extremely low mass of micro- and nano-particles and the ability to determine the chemical composition of the individual entities. The notion of using optical levitation to trap individual particles was demonstrated in the past century. Recently we have proposed the multielemental analysis of individual nanoparticles in optical traps using LIBS. In this lecture, the fundamentals of optical trapping of nanoparticles in air will be presented. The specific excitation and ionization processes leading to efficient optical detection and an analysis of the photon emission efficiency will be discussed. Finally, some limiting factors involved in our approach and prospective directions for improvement will be presented.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Chemistry in the laser-induced plasma

Since the first uses of LIBS, it is known that the laser induced plasma, as many other atom reservoirs, is a dynamic system that evolves rapidly to stable species after the end of the laser pulse. LIBS of metallic targets, which is the best established body of knowledge in this area of research, reveals the existence of a limited number of reactions between the excited and ionized atoms and atmospheric oxygen. The oxides formed may be used for characterizing the original sample, as for instance using the recently demonstrated application of LIBS for isotopic analysis at atmospheric pressure. The case of LIBS of organic compounds is much more complex. Recent investigations reveal that reactions in the plasma between fragments formed by dissociation of the original compound and by reactions of these fragments with the gas surrounding the plasma are extensive. While these reactions tend to complicate the spectroscopy and its interpretation, the products formed and the way they interact can be exploited for assigning the identity of the original compound. In this talk, a discussion of the several factors affecting the plasma chemistry of a number of molecular compounds will be presented. Factors influencing the formation of emitting species and some applications in the chemical analysis of organic samples will be discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

From the sea bottom to the red planet with laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) constitutes one of the most active research fields in analytical science. Among several important features, ability for adaptation to radically different scenarios constitutes its most valuable asset. For instance, technology based on LIBS has been developed for sub-sea operations and for planetary exploration, two extreme environments that require analytical solutions not available for most measurement techniques. In this talk, a discussion will be presented on the challenges represented by these analyses and the solutions envisaged using advanced LIBS approaches.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Spectral identification in the attogram regime through laser induced breakdown spectroscopy of single optically-trapped nanoparticles in air

Current trends in nanoengineering are bringing along new structures of diverse chemical compositions that need to be meticulously defined to ensure their correct operation. Few methods can provide the sensitivity required to carry out measurements on individual nanosubjects without tedious sample pre-treatment or data analysis. In the present study, we introduce a pathway for the full elemental identification of single nanoparticles that avoids suspension in liquid media by means of optical trapping and laser-induced plasma spectroscopy. We demonstrate spectroscopic detection and identification of individual Cu nanoparticles of masses down to 73 attograms and report, for the first time, stable optical trapping in air and manipulation of Cu particles from 25 to 70 nm in diameter. We found an increase in the absolute number of photons produced as size of the particles decreased; pointing towards a more efficient excitation of ensembles of only 7 x exp(-5) Cu atoms in the onset plasma.Universidad de Málaga. Campus de Excelencia Internacional Andalucia Tec

OC-OT-LIBS: A novel approach to the chemical characterization of single particles

Spectral identification of individual micro- and nano-sized particles by the sequential intervention of optical catapulting, optical trapping and laser-induced breakdown spectroscopy is presented [1]. The three techniques are used for different purposes. Optical catapulting (OC) serves to put the particulate material under inspection in aerosol form [2-4]. Optical trapping (OT) permits the isolation and manipulation of individual particles from the aerosol, which are subsequently analyzed by laser-induced breakdown spectroscopy (LIBS). Once catapulted, the dynamics of particle trapping depends on the laser beam characteristics (power and intensity gradient) and on the particle properties (size, mass and shape). Particles are stably trapped in air at atmospheric pressure and can be conveniently manipulated for a precise positioning for LIBS analysis. The spectra acquired from the individually trapped particles permit a straightforward identification of the inspected material. The current work focuses on the development of a procedure for simultaneously acquiring dual information about the particle under study via LIBS and time-resolved plasma images by taking advantage of the aforementioned features of the OC-OT-LIBS instrument to align the multiple lines in a simple yet highly accurate way. The plasma imaging does not only further reinforce the spectral data, but also allows a better comprehension of the chemical and physical processes involved during laser-particle interaction. Also, a thorough determination of the optimal excitation conditions generating the most information out of each laser event was run along the determination of parameters such as the width of the optical trap, its stability as a function of the laser power and the laser wavelength. The extreme sensibility of the presented OC-OT-LIBS technology allows a detection power of attograms for single/individual particle analysis.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Chemical Fingerprints in an Underwater Archaeological Shipwreck using a Remote Laser-Induced Breakdown Spectroscopy System

Nowadays, one of the most important areas of interest in archeology is the characterization of the submersed cultural heritage. Mediterranean Sea is rich in archaeological findings due to storms, accidents and naval battles since prehistoric times. Chemical analysis of submerged materials is an extremely valuable source of information on the origin and precedence of the wrecks, and also the raw materials employed during the manufacturing of the objects found in these sites. Sometimes extracting the archeological material from the marine environment is not practical due to the size of the sample, or is not permitted by the legislation or preservation practices. In these cases, the in-situ analysis turns into the only alternative. The versatility of laser-induced breakdown spectroscopy (LIBS) has been successfully tested in oceanography [1]. Advantages such as rapid and in situ analysis with no sample preparation make LIBS a suitable alternative for field measurements. A fiber-optics-based remote instrument has been designed for the recognition and identification of artworks in underwater archaeological shipwrecks. The LIBS prototype featured both single-pulse (SP-LIBS) and multipulse excitation (MP-LIBS). The use of multi-pulse excitation allowed an increased laser beam energy (up to 95 mJ) transmitted through the optical fiber. This excitation mode results in an improved performance of the equipment in terms of extended range of analysis (to a depth of 50 m) and a broader variefy of samples to be analyzed (i.e., rocks, marble, ceramics and concrete). In this work, parametric studies in the laboratory such as gas flow pressure, beam focal conditions and angle of incidence, among others, were performed to optimize the best conditions for field analysis. Finally, results obtained in these field trials confirmed the capability of remole LIBS for in-situ analysis of underwater archeological samples.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Laser-induced breakdown spectroscopy. Un herramienta exclusiva para el análisis químico de objetos distantes

El desarrollo y aplicación de tecnologías avanzadas de láser para la caracterización de materiales ofrece soluciones rentables para una variedad de problemas técnicos y de investigación en diversas áreas de aplicación, incluyendo la microelectrónica, tecnologías de control de procesos, medio ambiente, el patrimonio cultural, la defensa y la seguridad, y los productos de acero y procesos. En esta presentación se tratará sobre la Inspección de nanodominios y estrategias para el análisis de los objetos distantes utilizando LIBS. Los experimentos incluyen sistemas de cartografía composicional, los instrumentos de análisis remoto y prototipos desplegables portátiles para análisis de campo. Se discutirán también los sistemas de análisis láser de materiales bajo el agua y de la inspección de materiales a distancias de hasta 100 m.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

LIBS analysis of individual nanoparticles: attogram detection limits in optical traps

LIBS ANALYSIS OF INDIVIDUAL NANOPARTICLES: ATTOGRAM DETECTION LIMITS IN OPTICAL J. Laserna* Department of Analytical Chemistry, University of Malaga, Malaga, Spain *[email protected] Single particle characterization still constitutes a challenge to contemporary chemical analysis. Considerable effort worldwide is being devoted to conceive experimental strategies providing detection capabilities compatible with the extremely low mass of micro- and nano-particles and the ability to determine the chemical composition of the individual entities. The notion of using optical levitation to trap individual particles was demonstrated in the past century. Recently we have proposed the multielemental analysis of individual nanoparticles in optical traps using LIBS. In this lecture, the fundamentals of optical trapping of nanoparticles in air will be presented. The specific excitation and ionization processes leading to efficient optical detection and an analysis of the photon emission efficiency will be discussed. Finally, some limiting factors involved in our approach and prospective directions for improvement will be presented.Universidad de Málaga. Campus de Excelencia Internacional Andalucia Tec