Download or read book New Enhanced Sensitivity Infrared Laser Spectroscopy Techniques Applied to Reactive Plasmas and Trace Gas Detection written by Stefan Welzel and published by Logos Verlag Berlin GmbH. This book was released on 2009 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Infrared laser absorption spectroscopy (IRLAS) employing both tuneable diode and quantum cascade lasers (TDLs, QCLs) has been applied with both high sensitivity and high time resolution to plasma diagnostics and trace gas measurements. TDLAS combined with a conventional White type multiple pass cell was used to detect up to 13 constituent molecular species in low pressure Ar/H2/N2/O2 and Ar/CH4/N2/O2 microwave discharges, among them the main products such as H2O, NH3, NO and CO, HCN respectively. The hydroxyl radical has been measured in the mid infrared (MIR) spectral range in-situ in both plasmas yielding number densities of between 1011 ... 1012 cm-3. Strong indications of surface dominated formation of either NH3 or N2O and NO were found in the H2-N2-O2 system. In methane containing plasmas a transition between deposition and etching conditions and generally an incomplete oxidation of the precursor were observed. The application of QCLs for IRLAS under low pressure conditions employing the most common tuning approaches has been investigated in detail. A new method of analysing absorption features quantitatively when the rapid passage effect is present is proposed. If power saturation is negligible, integrating the undisturbed half of the line profile yields accurate number densities without calibrating the system. By means of a time resolved analysis of individual chirped QCL pulses the main reasons for increased effective laser line widths could be identified. Apart from the well-known frequency down chirp non-linear absorption phenomena and bandwidth limitations of the detection system may significantly degrade the performance and accuracy of inter pulse spectrometers. The minimum analogue bandwidth of the entire system should normally not fall below 250 MHz. QCLAS using pulsed lasers has been used for highly time resolved measurements in reactive plasmas for the first time enabling a time resolution down to about 100 ns to be achieved. A temperature increase of typically less than 50 K has been established for pulsed DC discharges containing Ar/N2 and traces of NO. The main NO production and depletion reactions have been identified from a comparison of model calculations and time resolved measurements in plasma pulses of up to 100 ms. Considerable NO struction is observed after 5 ... 10 ms due to the impact of N atoms. Finally, thermoelectrically cooled pulsed and continuous wave (cw) QCLs have been employed for high finesse cavity absorption spectroscopy in the MIR. Cavity ring down spectroscopy (CRDS) has been performed with pulsed QCLs and was found to be limited by the intrinsic frequency chirp of the laser suppressing an efficient intensity build-up inside the cavity. Consequently the accuracy and advantage of an absolute internal absorption calibration is not achievable. A room temperature cw QCL was used in a complementary cavity enhanced absorption spectroscopy (CEAS) configuration which was equipped with different cavities of up to 1.3 m length. This spectrometer yielded path lengths of up to 4 km and a noise equivalent absorption down to 4 x 10-8 cm-1Hz-1/2. The corresponding molecular concentration detection limit (e.g. for CH4, N2O and C2H2 at 1303 cm-1/7.66 Aem) was generally below 1 x 1010 cm-3 for 1 s integration times and one order of magnitude less for 30 s integration times. The main limiting factor for achieving even higher sensitivity is the residual mode noise of the cavity. Employing a 0.5 m long cavity the achieved sensitivity was good enough for the selective measurement of trace atmospheric constituents at 2.2 mbar.
Download or read book Advances in Spectroscopy Molecules to Materials written by Dheeraj Kumar Singh and published by Springer Nature. This book was released on 2019-10-24 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents and discusses recent developments in the broad field of spectroscopy, providing the reader with an updated overview. The main objective is to introduce them to recent innovations and current trends in spectroscopy applied to molecules and materials. The book also brings together experimentalists and theoreticians to highlight the multidimensional aspects of spectroscopy and discuss the latest issues. Accordingly, it provides insights not only into the general goals of spectroscopy, but also into how the various spectroscopic techniques represent a toolbox that can be used to gain a more detailed understanding of molecular systems and complex chemical problems. Besides technical aspects, basic theoretical interpretations of spectroscopic results are also presented. The spectroscopy techniques discussed include UV-visible absorption spectroscopy, Raman spectroscopy, IR absorption spectroscopy, fluorescence spectroscopy, and time-resolved spectroscopy. In turn, basic tools like lasers and theoretical modeling approaches are also presented. Lastly, applications for the characterization of fundamental properties of molecules (environmental aspects, biomolecules, pharmaceutical drugs, hazardous molecules, etc.) and materials (nanomaterials, nuclear chemistry materials, biomaterials, etc.) are discussed. Given its scope, the book offers a valuable resource for researchers from various branches of science, and presents new techniques that can be applied to their specific problems.
Download or read book Cavity Enhanced Spectroscopy and Sensing written by Gianluca Gagliardi and published by Springer. This book was released on 2013-10-19 with total page 537 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book reviews the dramatic recent advances in the use of optical resonators for high sensitivity and high resolution molecular spectroscopy as well as for chemical, mechanical and physical sensing. It encompasses a variety of cavities including those made of two or more mirrors, optical fiber loops, fiber gratings and spherical cavities. The book focuses on novel techniques and their applications. Each chapter is written by an expert and/or pioneer in the field. These experts also provide the theoretical background in optics and molecular physics where needed. Examples of recent breakthroughs include the use of frequency combs (Nobel prize 2005) for cavity enhanced sensing and spectroscopy, the use of novel cavity materials and geometries, the development of optical heterodyne detection techniques combined to active frequency-locking schemes. These methods allow the use and interrogation of optical resonators with a variety of coherent light sources for trace gas detection and sensing of strain, temperature and pressure.
Download or read book Molecular and Laser Spectroscopy written by V.P. Gupta and published by Elsevier. This book was released on 2020-07-10 with total page 706 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular and Laser Spectroscopy, Advances and Applications: Volume 2 gives students and researchers an up-to-date understanding of the fast-developing area of molecular and laser spectroscopy. This book covers basic principles and advances in several conventional as well as new and upcoming areas of molecular and laser spectroscopy, such as a wide range of applications in medical science, material science, standoff detection, defence and security, chemicals and pharmaceuticals, and environmental science. It covers the latest advancements, both in terms of techniques and applications, and highlights future projections. Editors V.P. Gupta and Yukihiro Ozaki have brought together eminent scientists in different areas of spectroscopy to develop specialized topics in conventional molecular spectroscopy (Cavity ringdown, Matrix Isolation, Intense THz, Far- and Deep- UV, Optogalvanic ), linear and nonlinear laser spectroscopy (Rayleigh & Raman Scattering), Ultrafast Time-resolved spectroscopy, and medical applications of molecular spectroscopy. and advanced material found in research articles. This new volume expands upon the topics covered in the first volume for scientists to learn the latest techniques and put them to practical use in their work. Covers several areas of spectroscopy research and expands upon topics covered in the first volume Includes exhaustive lists of research articles, reviews, and books at the end of each chapter to further learning objectives Uses illustrative examples of the varied applications to provide a practical guide to those interested in using molecular and laser spectroscopy tools in their research
Download or read book Laser Spectroscopy for Sensing written by Matthieu Baudelet and published by Elsevier. This book was released on 2014-02-15 with total page 601 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser spectroscopy is a valuable tool for sensing and chemical analysis. Developments in lasers, detectors and mathematical analytical tools have led to improvements in the sensitivity and selectivity of spectroscopic techniques and extended their fields of application. Laser Spectroscopy for Sensing examines these advances and how laser spectroscopy can be used in a diverse range of industrial, medical, and environmental applications. Part one reviews basic concepts of atomic and molecular processes and presents the fundamentals of laser technology for controlling the spectral and temporal aspects of laser excitation. In addition, it explains the selectivity, sensitivity, and stability of the measurements, the construction of databases, and the automation of data analysis by machine learning. Part two explores laser spectroscopy techniques, including cavity-based absorption spectroscopy and the use of photo-acoustic spectroscopy to acquire absorption spectra of gases and condensed media. These chapters discuss imaging methods using laser-induced fluorescence and phosphorescence spectroscopies before focusing on light detection and ranging, photothermal spectroscopy and terahertz spectroscopy. Part three covers a variety of applications of these techniques, particularly the detection of chemical, biological, and explosive threats, as well as their use in medicine and forensic science. Finally, the book examines spectroscopic analysis of industrial materials and their applications in nuclear research and industry. The text provides readers with a broad overview of the techniques and applications of laser spectroscopy for sensing. It is of great interest to laser scientists and engineers, as well as professionals using lasers for medical applications, environmental applications, military applications, and material processing. Presents the fundamentals of laser technology for controlling the spectral and temporal aspects of laser excitation Explores laser spectroscopy techniques, including cavity-based absorption spectroscopy and the use of photo-acoustic spectroscopy to acquire absorption spectra of gases and condensed media Considers spectroscopic analysis of industrial materials and their applications in nuclear research and industry
Download or read book Applications of Infrared Laser Spectroscopy to Breath Analysis written by Beth L. Cummings and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented in this thesis is concerned with development of spectroscopic detection methods based on absorption spectroscopy using semiconductor lasers, with particular ref- erence to the field of medical diagnostics through breath analysis. The first part of this thesis deals with the design and testing of a prototype analyser for simultaneous monitoring of the exchange gases 02, C02 and H20 in breath. The aim of this analyser is to provide information required to monitor respiration, with potential use in intensive care monitoring or during anaesthesia. The relatively high concentrations of these gases in breath and read- ily available diode laser sources make detection in the near-infrared (NIR) ideal. However, the relatively weakly absorbing A-band 02 transitions at 760 nm require the application of a sensitive spectroscopic method, cavity enhanced absorption spectroscopy (CEAS). In contrast, CO2 and H20 are monitored using direct single pass absorption spectroscopy, with transitions arising from the 21/1 + 1/3 band at 2 uu: and 1/1 + 1/3 band at 1.3 p,m, re- spectively. It has been demonstrated that these gases can be detected simultaneously over a short pathlength (2.74 - 4 cm) in the respiratory flow by combining various spectroscopic methodologies and real-time data analysis. This analyser is shown to offer a viable alter- native for monitoring respiration, exhibiting absolute detection limits of changes of 0.26 % O2, 0.02 % CO2 and 0.003 % H20 with a 10 ms time resolution, which are comparable to current mass spectrometry based methods, but without their inherent delays. Following this, investigations into the detection of the main gas constituents in breath in the NIR employing noise-reduction modulation based spectroscopic techniques, namely wavelength and frequency modulation (WMS and FMS respectively) are also reported. The described WMS studies on water at 1.37 ust: provide a demonstration of conventional WMS detection, as well as a "proof-of-principle" example of a relatively new approach to calibrat- ing the non-absolute information obtained from a WMS absorption signal. Typically WMS spectra are calibrated using mixtures of known gas concentrations or an absolute direct absorption spectrum where possible. In this work however, a self-calibrating method, the phasor decomposition method (PDM), is employed and the returned concentration from this ~alibration is compared to direct absorption measurement. From this, the calculated concentration using the PDM is found to differ by 9 % from the concentration value ob- tained by direct absorption, providing an alternative method of calibration for when direct absorption measurements are not possible. The use of FMS in the NIR is also demon- strated as a potential alternative to CEAS for monitoring O2 at 760 nm. FMS detection is performed on atmospherically broadened 02 and a time-normalised O!min(t) of 2.45x10-6 cm-1 s~ is obtained, which is two orders of magnitude less sensitive than the value of 1 O!min(t) = 2.35x10-8 cm "! S2 obtained with CEAS. This combined with the experimental I requirements of an FMS system, make its use for detection of 02 a less practicable option compared to CEAS for real-time breath analysis. The latter work in this thesis involves a change in focus to detection of trace gases in breath in the mid-infrared (MlR). The move of spectroscopic detection to the MlR exploits the larger absorption cross-sections available in this region, and to achieve this, a relatively new form of semiconductor laser, the quantum cascade laser (QCL) is used. The design of a continuous wave QCL spectrometer at 8 usx: and its operating characteristics are demon- strated and improvements in its performances are also discussed. This QCL system is then utilised to demonstrate the potential of monitoring species in breath, namely the narrow- band absorber methane and the broadband absorber acetone, taking into consideration the potential interference from other absorbing species in breath and the different spectroscopic characteristics exhibited by these molecules. Finally, the potential to further improve the sensitive detection of trace gases in breath in the MlR is also investigated with studies on the use of CEAS and multipass cells. In this work, the molecule of interest is the biomarker OGS, using transitions of the 2V2 band at 1031 cm-I, that are probed using a 10 usx: QCL. The application of CEAS in the MlR is not as well developed as in the NIR, and the experimental consequences of using optical cavities at these wavelengths, where equipment tends to be more limited, are investigated and sensitivities discussed in the context of other literature. The experimental procedure of optimising a cavity for CEAS using the off-axis alignment method is also studied in detail, as well as the addition ofWMS to further improve the signal quality. An effective absorption pathlength of ,....., 100 m was achieved in the cavity, with a bandwidth reduced O!min(BW) 1 of 1.7x10-7 cm"? HZ-2 using WMS CEAS achieved. With the poorer quality optics and limitations in equipment in the MlR for CEAS experiments, the use of a multipass cell, a 238 m Herriott cell, is also investigated as an alternative to the use of an optical cavity at 10 tui". Detection of OCS using direct absorption and WMS is demonstrated in the 1 Herriott cell, achieving O!min(BW) = 2.03xlO-8 cm "! HZ-2 using WMS. This shows an improvement in sensitivity compared to WMS CEAS, and also shows the potential for future work on biomarker detection, as it approaches the r-- ppb levels required for breath analysis.
Download or read book Mid infrared Laser Spectroscopy for Trace Gas Detection written by Katherine Marya Manfred and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laser Spectroscopy written by Wolfgang Demtröder and published by Springer Science & Business Media. This book was released on 2008-07-23 with total page 797 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material. This new edition has been completely revised, especially the chapters on non linear spectroscopy, ion trapping, ultra short laser pulses and new developments. Fifty new figures illustrate the newest developments and results. The author is one of the most renowned experts in this area and no other book with this broad scope is available.
Download or read book Laser Spectroscopy written by E. Roland Menzel and published by CRC Press. This book was released on 1994-09-01 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work describes experimental techniques using laser spectroscopy and presents specific practical applications for this technology in many fields, including physics, engineering, chemistry, medicine and bioscience. The general spectroscopic features of molecules are delineated; transition metal and rare earth complexes are examined; and transition selection rules are explained.
Download or read book Ultrasensitive Laser Spectroscopy written by David Kliger and published by Elsevier. This book was released on 2012-12-02 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrasensitive Laser Spectroscopy covers the experimental methods involved in various sensitive techniques to which lasers have been applied for the study of weak transitions. This book is organized into seven chapters. Each chapter discusses the theories, experiments, and application of the specific technique. A discussion on the advantages, disadvantages, and modifications made in each technique is also provided. Ultrasensitive techniques considered in this text include photoacoustic, one- and two-photon excitation, absorption, mass, and laser ionization spectroscopies. Other chapters examine the techniques of laser intracavity-enhanced, laser absorption, and emission spectroscopy. This book will be of value to spectroscopists, analytical chemists, and researchers in the field of ultrasensitive analysis.
Download or read book Environmental Trace Gas Detection Using Laser Spectroscopy written by and published by . This book was released on 1998 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laser Spectroscopy 2 written by Wolfgang Demtröder and published by Springer. This book was released on 2015-01-07 with total page 773 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material, e.g., ultrafast lasers (atto- and femto-second lasers), coherent matter waves, Doppler-free Fourier spectroscopy, interference spectroscopy, quantum optics and gravitational waves and still more applications in chemical analysis, medical diagnostics, and engineering.
Download or read book Laser Spectroscopy written by Wolfgang Demtröder and published by Springer Science & Business Media. This book was released on 2002-10-08 with total page 1012 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material, e.g., frequency doubling in external cavities, reliable cw-parametric oscillators, tunable narrow-band UV sources, more sensitive detection techniques, tunable femtosecond and sub-femtosecond lasers (X-ray region and the attosecond range), control of atomic and molecular excitations, frequency combs able to synchronize independent femtosecond lasers, coherent matter waves, and still more applications in chemical analysis, medical diagnostics, and engineering.
Download or read book Analytical Laser Spectroscopy written by S. Martellucci and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the Proceedings of a two-week NATO A.S.I. on "Analytical Laser Spectroscopy", held from September 23 to October 3, 1982 in Erice, Italy. This is the 9th annual course of Inter national School of Quantum Electronics organized under the auspices of the "E. Majorana" Center for Scientific Culture. The Advanced Study Institute has been devoted to the analytical applications of lasers in spectroscopy. Atomic and molecular spec troscopy is one of the research fields in which the use of lasers has had a dramatic impact. New spectral information, difficult or impos sible to gather by classical spectroscopy, extremely high resolution spectroscopy of atoms and molecules made possible by the overcoming of the Doppler effect, selective excitation and detection of single atomic and molecular quantum states are just few typical examples of how laser sources have revolutionized the field, offering challenging problems of both fundamental and applied nature. Among the possible approaches to a course on Analytical Laser Spectroscopy, the one which emphasizes the scientific and technologi cal aspects of the advanced laser techniques when applied to chemical analysis has been chosen. In fact, it reflects the new policy of the School to stress the advanced scientific and technological achieve ments in the field of Quantum Electronics. Accordingly, the course has given the broadest information on the ultimate performances of analytical laser spectroscopy techniques and the perspectives of their applications.
Download or read book Handbook of Laser Induced Breakdown Spectroscopy written by David A. Cremers and published by John Wiley & Sons. This book was released on 2013-03-15 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Applied Laser Spectroscopy written by David L. Andrews and published by Wiley-VCH. This book was released on 1992 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Laser Based Spectroscopic Techniques for Trace Gas Detection Based on Optical Cavity Enhancement and Multipass Absorption Cells written by Johnny Chung Leung Chu and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
