Imaging and Spectroscopy of Laser Produced Annular Plasmas PDF Download
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Author: Ben Delaney
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Laser induced breakdown spectroscopy (LIBS) has emerged as a commonly used analytical technique for both qualitative elemental identification and quantitative concentration determination in various academic and industrial fields. The ultimate performance of LIBS is dependent on the signal to background ratio (SBR) of the spectra which are acquired from a sample and is quantified as the limit of detection (LOD) of the technique. A significant body of work has already been reported in the literature aimed at lowering of the LOD of LIBS. This work includes investigations into the effects of; laser fluence, wavelength and pulse length as well as space and time optimization, along with double pulse plasma formation and reheating arrangements. The aim of the work presented here is to generate and investigate the stagnation layer formed in vacuo, at the centre of an annular plasma, and to employ it in a LIBS experiment on trace Cu in Al. This is achieved by retrofitting a single optical element, namely an axicon, to the focusing lens normally used for point plasma formation. Spatially and temporally resolved imaging and spectroscopy are employed to track the formation and evolution of a stagnation layer at the centre of an annular plasma. Comparisons of these imaging and spectroscopy measurements are drawn with those obtained for a stagnation layer formed between two point seed plasmas, as well as for single laser produced plasma. An off axis parabolic mirror was used to carry out imaging and spectroscopy along the plasma expansion axis, normal to the target. A simple relay lens system was used for imaging and spectroscopy parallel to the target surface. The former is, to the best of my knowledge, the first time such an investigation into stagnation layers has been undertaken. The targets used were slabs of aluminium with trace amounts of copper. Point, dual colliding and annular colliding plasmas were investigated to determine their relative merits in laser induced breakdown spectroscopy. It found that the limit-of-detection for trace amounts of Cu in Al is lowest for annular plasmas formed at low laser pulse energies of ca. 25 - 30 mJ.
Author: Ben Delaney
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Laser induced breakdown spectroscopy (LIBS) has emerged as a commonly used analytical technique for both qualitative elemental identification and quantitative concentration determination in various academic and industrial fields. The ultimate performance of LIBS is dependent on the signal to background ratio (SBR) of the spectra which are acquired from a sample and is quantified as the limit of detection (LOD) of the technique. A significant body of work has already been reported in the literature aimed at lowering of the LOD of LIBS. This work includes investigations into the effects of; laser fluence, wavelength and pulse length as well as space and time optimization, along with double pulse plasma formation and reheating arrangements. The aim of the work presented here is to generate and investigate the stagnation layer formed in vacuo, at the centre of an annular plasma, and to employ it in a LIBS experiment on trace Cu in Al. This is achieved by retrofitting a single optical element, namely an axicon, to the focusing lens normally used for point plasma formation. Spatially and temporally resolved imaging and spectroscopy are employed to track the formation and evolution of a stagnation layer at the centre of an annular plasma. Comparisons of these imaging and spectroscopy measurements are drawn with those obtained for a stagnation layer formed between two point seed plasmas, as well as for single laser produced plasma. An off axis parabolic mirror was used to carry out imaging and spectroscopy along the plasma expansion axis, normal to the target. A simple relay lens system was used for imaging and spectroscopy parallel to the target surface. The former is, to the best of my knowledge, the first time such an investigation into stagnation layers has been undertaken. The targets used were slabs of aluminium with trace amounts of copper. Point, dual colliding and annular colliding plasmas were investigated to determine their relative merits in laser induced breakdown spectroscopy. It found that the limit-of-detection for trace amounts of Cu in Al is lowest for annular plasmas formed at low laser pulse energies of ca. 25 - 30 mJ.
Author: Kevin D. Kavanagh
Publisher:
ISBN:
Category :
Languages : en
Pages : 225
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Book Description
Author: Jessica Mcnutt
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Laser-induced breakdown spectroscopy (LIBS) has been identied as a promising technique for the detection and characterization of nuclear materials and other materials relevant for nuclear forensics and international safeguards applications. LIBS is a material characterization method whereby a short-pulse, high-intensity laser is focused on the surface of a target to generate a plasma for spectral analysis to determine the elemental and potentially isotopic composition of the target. Shadowgraphic and fast-frame photographic imaging are two established techniques used to study the time-evolution and the rate of expansion of laser-produced plasmas over hundreds of nanoseconds. The modication of a LIBS experimental setup to include the capability to take photographic images and high-temporal resolution shadowgraphic images is presented. Analysis of uranium samples was performed in air and vacuum conditions. Shadowgraphic imaging was used to analyze laser produced plasma evolution in the rst 8 ns following laser-energy deposition on the surface. Algorithms were developed to measure the plasma radius as a function of time and the results of that analysis were compared to the Sedov-Taylor model.
Author: Nichola Walsh
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
During the interaction of an intense laser pulse with a solid metal target, a high temperature, high density plasma is formed. Pulsed laser ablation has attracted much interest over the past fifty years with experimental and theoretical work largely focussed on the study of laser produced plasmas in vacuum. The study of pulsed laser ablation has been largely motivated from a materials processing perspective, with the characterisation of thin films using pulsed laser deposition of particular interest. Another application resulting from the study of laser produced plasmas is the use of laser-induced breakdown spectroscopy (LIBS) for elemental composition and quantitative analysis of samples. LIBS is now a widely used technique employed in various fields including environmental analysis, forensics and biomedical applications. While much work has been carried out on pulsed ablation of materials in vacuum and gas ambient, comparatively little research has been done on ablation in liquid media. As a result, the fundamental understanding of laser produced plasmas in liquids remains insufficient. Using techniques such as time resolved imaging and spectroscopy, a full characterisation of the plasma formed in air was undertaken as a comparison to the subsequent investigation of the plasma formed in water ambient. Single pulse studies revealed information on the dynamic evolution of a laser plasma formed in the liquid phase where strong confinement and broadband emission were the main observations. Shadowgraphy measurements were performed to examine the dynamic behaviour of the cavitation bubble that eventually forms post plasma ignition. The results of time resolved optical emission measurements from within the cavitation bubble using a second laser pulse reveal for the first time the full dynamic evolution of the plasma formed in such an environment.
Author: Vivek K. Singh
Publisher: John Wiley & Sons
ISBN: 1119758424
Category : Science
Languages : en
Pages : 2162
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Book Description
Laser Induced Breakdown Spectroscopy (LIBS) Essential resource covering the field of LIBS, with respect to its fundamentals, established and novel applications, and future prospects Laser Induced Breakdown Spectroscopy (LIBS), presents in two comprehensive volumes a thorough discussion of the basic principles of the method, including important recently available data which can lead to a better characterization of the LIBS plasma. This extensive work contains detailed discussions on the lasers, spectrometers, and detectors that can be used for LIBS apparatuses and describes various instrumentation, ranging from basic setups to more advanced configurations. As a modern resource, the work includes the newest advances and capabilities of LIBS instruments, featuring the recent developments of Dual-Pulse LIBS, Femtosecond LIBS, and Micro-LIBS as well as their applications. Throughout, the contributions discuss the analytical capabilities of the method in terms of detection limits, accuracy, and precision of measurements for a variety of samples. Lastly, an extensive range of applications is presented, including food technology, environmental science, nuclear reactors, nanoscience and nanotechnology, and biological and biomedical developments. Sample topics covered within the work include: iagnostics of laser induced plasma (LIP): LIBS plasma and its characteristics, factors affecting the LIBS plasma, methods of enhancing LIBS sensitivity, and LTE/non-LTE plasmas Instrumental developments in LIBS: light collection system and spectral detection systems, handheld LIBS, deep sea LIBS, and industrial sorters and analyzers Femtosecond laser ablation: laser-matter interaction, laser absorption, energy transport, ablation mechanisms and threshold, and plasma characterization Micro-analysis and LIBS imaging: microjoule laser sources, scaling libs to microjoule energies, micrometer scaling, advanced applications, and future prospects Spectroscopic and analytical scientists working with LIBS will find this wide-ranging reference immensely helpful in developing LIBS instrumentation and applications. Researchers and students in natural sciences and related programs of study will be able to use the work to acquire foundational knowledge on the method and learn about cutting-edge advancements being made in the field.
Author: Colm Fallon
Publisher:
ISBN:
Category :
Languages : en
Pages : 141
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Book Description
Recently prepulse techniques such as dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) have emerged as commonly used analytical techniques for qualitative and quantitative elemental investigations in various research fields and disciplines such as industrial, defense and medical applications. The performance of the DP-LIBS technique is strongly dependent on the choice of the experimental conditions. The key parameters that affect its performance are the target properties, laser wavelength, pulse duration, energy and spot-size, interpulse delay times, delay time of observations, ambient background gas pressure and geometrical setup of the optics. The DP-LIBS approach provides significant enhancement in the intensities of emission lines and their lifetimes, up to two orders of magnitude greater than conventional single pulse laser induced breakdown spectroscopy. The aim of the work presented here is to further advance prepulse techniques, as well as other methods to control species density, with a view to optimise emission in the visible wavelength range. In particular, a new technique involving reheating the stagnation layer formed at the collision front between two (or more) colliding plasmas is explored. Spatially and temporally resolved imaging and spectroscopy of the interaction region between two colliding plasmas are employed to demonstrate for the first time that pumping of an optimised stagnation layer significantly increases the intensity emission and duration of selected spectral lines. This technique offers the promise of tunable density and tunable energy (temperature) plasmas. It will potentially increase both the lifetimes and intensities of spectral lines in laser produced plasmas by creating relatively low density - high energy plasmas which can overcome the problem of flux loss due to opacity, which leads to the attenuation of discrete emission lines with a concomitant reduction in line contrast, signal-to-noise ratio (SNR) and signal-to-background ratio (SBR). The latter is a key parameter in determining the limit-of-detection (LOD) of the LIBS technique. Other applications of stagnation layers include the development of 'target fuel' for Extreme UltraViolet (EUV) and X-ray light sources with an especial emphasis on generating high repetition rate, preheated droplet-like targets that can compete with the current liquid drop targets. The latter suffer from clogging at the jet nozzle due to adiabatic expansion freezing. Also, unlike stagnation layers the basic parameters of the droplet fuel cannot be easily varied in the way that stagnation layers allow.
Author: D. W. Scudder
Publisher:
ISBN:
Category :
Languages : en
Pages : 169
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Book Description
The research performed under this program has covered a broad range of subjects involving laser interaction with both gaseous and solid target laser plasmas, and with development of plasma diagnostic techniques suitable for our laser-produced plasmas. Included are detailed descriptions of research activities during fiscal years 1978 and 1979. These include a study of stimulated Brillouin scattering in transverse magnetic fields; development of X-ray diagnostics including X-ray continuum measurements, spectroscopy, and imaging techniques and their use in studying solid target plasmas; development of a fast schlieren photography system; and a theoretical study of nonlinear scattering techniques for plasma diagnostics.
Author: David A. Cremers
Publisher: John Wiley & Sons
ISBN: 1118567366
Category : Science
Languages : en
Pages : 452
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Book Description
Starting from fundamentals and moving through a thorough discussion of equipment, methods, and techniques, the Handbook of Laser-Induced Breakdown Spectroscopy provides a unique reference source that will be of value for many years to come for this important new analysis method. The authors, with a total of over 60 years of experience in the LIBS method, use a combination of tutorial discussions ranging from basic principles up to more advanced descriptions along with extensive figures and photographs to clearly explain topics addressed in the text. In this second edition, chapters on the use of statistical analysis and advances in detection of weapons of mass destruction have been added. Tables of data related to analysis with LIBS have been updated. The Handbook of Laser-Induced Breakdown Spectroscopy, Second Edition: provides a thorough but understandable discussion of the basic principles of the method based on atomic emission spectroscopy, including recently available data leading to better characterization of the LIBS plasma; presents a discussion of the many advantages of the method along with limitations, to provide the reader a balanced overview of capabilities of the method; describes LIBS instrumentation ranging from basic set-ups to more advanced configurations; presents a comprehensive discussion of the different types of components (laser, spectrometers, detectors) that can be used for LIBS apparatuses along with suggestions for their use, as well as an up-to-date treatment of the newest advances and capabilities of LIBS instruments; presents the analytical capabilities of the method in terms of detection limits, accuracy, and precision of measurements for a variety of different sample types; discusses methods of sampling different media such as gases, liquids, and solids; presents an overview of some real-world applications of the method, with new emphasis on sampling of biologically and physically dangerous materials; provides an up-to-date list of references to LIBS literature along with the latest detection limits and a unique list of element detection limits using a uniform analysis method; provides annotated examples of LIBS spectra which can serve as references for the general reader and will be especially useful for those starting out in the field.
Author: William Paul Lewis
Publisher:
ISBN:
Category : Laser plasmas
Languages : en
Pages :
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Book Description
Author: Helmut H. Telle
Publisher: CRC Press
ISBN: 9781466588226
Category : Laser spectroscopy
Languages : en
Pages : 722
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Book Description
"Developments in and applications of laser spectroscopy and laser imaging are growing rapidly, specifically now that spectral analytical methodologies are merging with laser imaging techniques. There are now a wide range of established techniques having applications in many fields of chemistry and physics. The range of applications and techniques often makes it difficult for potential new users to come to an educated decision whether a particular technique may be suitable for his particular problem. It is the intention of this book to provide researchers, both in industry and academia, with a concise collection of laser analysis and imaging techniques. Though there are several books in specific areas of laser spectroscopy, there is a lack of a recent single volume publication providing a solid overview of the field as present texts are now dated in this fast moving field. Written by two leaders in the field it will introduce the reader to individual techniques in a tutorial-fashion; providing key examples and including details of the latest techniques. Though not written as a grad text it has potential to be used for a range of grad courses as well"--
