Download or read book Laser based Methods for Sensitive Trace Gas Detection written by 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 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 State of the art Laser Gas Sensing Technologies written by Yufei Ma and published by MDPI. This book was released on 2020-03-05 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trace gas sensing technologies are widely used in many applications, such as environmental monitoring, life science, medical diagnostics, and planetary exploration. On the one hand, laser sources have developed greatly due to the rapid development of laser media and laser techniques in recent years. Some novel lasers such as solid-state, diode, and quantum cascade lasers have experienced significant progress. At present, laser wavelengths can cover the range from ultraviolet to terahertz, which could promote the development of laser gas sensing technologies significantly. On the other hand, some new gas sensing methods have appeared, such as photothermal spectroscopy and photoacoustic spectroscopy. Laser spectroscopy-based gas sensing techniques have the advantages of high sensitivity, non-invasiveness, and allowing in situ, real-time observation. Due to the rapid and recent developments in laser source as well as the great merits of laser spectroscopy-based gas sensing techniques, this book aims to provide an updated overview of the state-of-the-art laser gas sensing technologies.

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 Special issue environmental trace gas detection using laser spectroscopy written by and published by . This book was released on 1998 with total page 133 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:

Download or read book Air Monitoring by Spectroscopic Techniques written by Markus W. Sigrist and published by John Wiley & Sons. This book was released on 1994-03-31 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: Leading experts discuss the characteristics, advantages, limitations and future aspects of modern spectroscopic techniques for environmental analysis. Demonstrates how these methods can be applied to trace gas detection and assessment. Concentrates on the latest techniques--both laser and non-laser based--which offer advantages for air pollution and gas monitoring as opposed to more conventional methods. Numerous examples of applications illustrate the potential of the techniques backed up by cutting-edge information and representative data.

Download or read book Sensitive Multi Species Emissions Monitoring written by and published by . This book was released on 2014 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes our development of spectroscopic chemical analysis techniques and spectral modeling for trace-gas measurements of highly-regulated low-concentration species present in flue gas emissions from utility coal boilers such as HCl under conditions of high humidity. Detailed spectral modeling of the spectroscopy of HCl and other important combustion and atmospheric species such as H 2 O, CO 2 , N 2 O, NO 2 , SO 2 , and CH 4 demonstrates that IR-laser spectroscopy is a sensitive multi-component analysis strategy. Experimental measurements from techniques based on IR laser spectroscopy are presented that demonstrate sub-ppm sensitivity levels to these species. Photoacoustic infrared spectroscopy is used to detect and quantify HCl at ppm levels with extremely high signal-to-noise even under conditions of high relative humidity. Additionally, cavity ring-down IR spectroscopy is used to achieve an extremely high sensitivity to combustion trace gases in this spectral region; ppm level CH 4 is one demonstrated example. The importance of spectral resolution in the sensitivity of a trace-gas measurement is examined by spectral modeling in the mid- and near-IR, and efforts to improve measurement resolution through novel instrument development are described. While previous project reports focused on benefits and complexities of the dual-etalon cavity ring-down infrared spectrometer, here details on steps taken to implement this unique and potentially revolutionary instrument are described. This report also illustrates and critiques the general strategy of IR- laser photodetection of trace gases leading to the conclusion that mid-IR laser spectroscopy techniques provide a promising basis for further instrument development and implementation that will enable cost-effective sensitive detection of multiple key contaminant species simultaneously.

Download or read book Laser Based Optical Detection of Explosives written by Paul M. Pellegrino and published by CRC Press. This book was released on 2018-09-03 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser-Based Optical Detection of Explosives offers a comprehensive review of past, present, and emerging laser-based methods for the detection of a variety of explosives. This book: Considers laser propagation safety and explains standard test material preparation for standoff optical-based detection system evaluation Explores explosives detection using deep ultraviolet native fluorescence, Raman spectroscopy, laser-induced breakdown spectroscopy, reflectometry, and hyperspectral imaging Examines photodissociation followed by laser-induced fluorescence, photothermal methods, cavity-enhanced absorption spectrometry, and short-pulse laser-based techniques Describes the detection and recognition of explosives using terahertz-frequency spectroscopic techniques Each chapter is authored by a leading expert on the respective technology, and is structured to supply historical perspective, address current advantages and challenges, and discuss novel research and applications. Readers are left with an in-depth understanding and appreciation of each technology’s capabilities and potential for standoff hazard detection.

Download or read book CO2 Laser Photoacoustic Spectroscopy for Ultrasensitive Gas Detection written by Ana Maria Bratu and published by LAP Lambert Academic Publishing. This book was released on 2014-11-11 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: CO2 Laser Photoacoustic Spectroscopy for Ultrasensitive Gas Detection is an easy-to-read guide to understanding the fundamentals of lasers, experimental method of CO2 laser spectroscopy and applications. This book provide informative data of a functional photoacoustic instrument with various applications in different disciplines. The wide scope of the chapters ranges from descriptions of the method, through the use of breath analysis in the study of physiological phenomena, to the identification of hazardous gases from surgical smoke. This book will provide a solid grounding for physicists, chemists, and engineers involved in trace gas analysis and detection.

Download or read book Laser in Environmental and Life Sciences written by Peter Hering and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive reference work illustrates the state of the art of laser-induced analytical methods in environmental and life sciences via an interdisciplinary approach. Ky techniques for remote sensing in the atmosphere as well as diagnostic methods for soil, water and air contamination and exhaled breath are described. Each a prominent scientist, the authors report on their current research; demonstrate that multi-disciplinary applications are possible; and employ examples on how existing environmental diagnostic methods have found their way into the life sciences.

Download or read book Green Electronics written by Cristian Ravariu and published by BoD – Books on Demand. This book was released on 2018-06-20 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Green Electronics book is intended to stimulate people's thinking toward the new concepts of an environment-friendly electronics - the main challenge in the future. The book offers multiple solutions to push the classical electronic industry toward green concepts, aided by nanotechnologies, with revolutionary features that provide low power consumption in electronics, use biomaterials for integrated structures, and include environmental monitoring tools. Based on organic semiconductors/insulators without toxic precursors, green electronic technologies launched promising devices like OLED, OTFT, or nano-core-shell transistors. The Green Electronics book successfully presents the recent directions collected worldwide and leaves free space for continuing year by year with new subtopics.

Download or read book Optical Gas Sensing written by Krzysztof M Abramski and published by Mdpi AG. This book was released on 2022-03-21 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical gas sensing is one of the fastest developing research areas in laser spectroscopy. Continuous development of new coherent light sources operating especially in the Mid-IR spectral band (QCL-Quantum Cascade Lasers, ICL-Interband Cascade Lasers, OPO-Optical Parametric Oscillator, DFG-Difference Frequency Generation, optical frequency combs, etc.) stimulates new, sophisticated methods and technological solutions in this area. The development of clever techniques in gas detection based on new mechanisms of sensing (photoacoustic, photothermal, dispersion, etc.) supported by advanced applied electronics and huge progress in signal processing allows us to introduce more sensitive, broader-band and miniaturized optical sensors. Additionally, the substantial development of fast and sensitive photodetectors in MIR and FIR is of great support to progress in gas sensing. Recent material and technological progress in the development of hollow-core optical fibers allowing low-loss transmission of light in both Near- and Mid-IR has opened a new route for obtaining the low-volume, long optical paths that are so strongly required in laser-based gas sensors, leading to the development of a novel branch of laser-based gas detectors. This Special Issue summarizes the most recent progress in the development of optical sensors utilizing novel materials and laser-based gas sensing techniques.

Download or read book Novel Laser based Gas Sensors for Trace Gas Detection in a Spacecraft Habitat written by Darrin Paul Leleux and published by . This book was released on 2002 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book State of the art Laser Gas Sensing Technologies written by Yufei Ma and published by . This book was released on 2020 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trace gas sensing technologies are widely used in many applications, such as environmental monitoring, life science, medical diagnostics, and planetary exploration. On the one hand, laser sources have developed greatly due to the rapid development of laser media and laser techniques in recent years. Some novel lasers such as solid-state, diode, and quantum cascade lasers have experienced significant progress. At present, laser wavelengths can cover the range from ultraviolet to terahertz, which could promote the development of laser gas sensing technologies significantly. On the other hand, some new gas sensing methods have appeared, such as photothermal spectroscopy and photoacoustic spectroscopy. Laser spectroscopy-based gas sensing techniques have the advantages of high sensitivity, non-invasiveness, and allowing in situ, real-time observation. Due to the rapid and recent developments in laser source as well as the great merits of laser spectroscopy-based gas sensing techniques, this book aims to provide an updated overview of the state-of-the-art laser gas sensing technologies.

Download or read book Fiber Laser System for the Detection of Trace Gas written by Jonas Kestutis Valiunas and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The research presented in this thesis is on the development of a trace gas detection system based on intracavity absorption spectroscopy (ICAS). The developed system was capable of detecting nitrous oxide (N2O) and acetylene (C2H2) gas at sub-ppmv levels. The P (12) rotational line of N2O at ~1522.20 nm, and the R (5) and R (4) rotational lines of C2H2 at ~1522.22 nm were used for detection. A fiber Bragg grating was incorporated into the ICAS cavity to enhance the system sensitivity by allowing the selection of strong absorption lines for detection. By operating the fiber laser based ICAS system at threshold, multiple circulations of the amplified spontaneous emission inside the cavity enhanced the system detection sensitivity. Further, the laser wavelength contained multi-longitudinal modes, which improved the system sensitivity. The system sensitivity was explored for two intra-cavity gas cells: a multi-pass Herriott cell and a gas cell based on a hollow-core photonic crystal fiber (HC-PCF). The system operated at room temperature and a polarization-maintaining erbium-doped fiber was used as a saturable absorber to help eliminate mode hopping in the laser cavity.

Download or read book Spectroscopy and Optical Diagnostics for Gases written by Ronald K. Hanson and published by Springer. This book was released on 2015-10-26 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text provides an introduction to the science that governs the interaction of light and matter (in the gas phase). It provides readers with the basic knowledge to exploit the light-matter interaction to develop quantitative tools for gas analysis (i.e. optical diagnostics) and understand and interpret the results of spectroscopic measurements. The authors pair the basics of gas‐phase spectroscopy with coverage of key optical diagnostic techniques utilized by practicing engineers and scientists to measure fundamental flow‐field properties. The text is organized to cover three sub‐topics of gas‐phase spectroscopy: (1) spectral line positions, (2) spectral line strengths, and (3) spectral lineshapes by way of absorption, emission, and scattering interactions. The latter part of the book describes optical measurement techniques and equipment. Key subspecialties include laser induced fluorescence, tunable laser absorption spectroscopy, and wavelength modulation spectroscopy. It is ideal for students and practitioners across a range of applied sciences including mechanical, aerospace, chemical, and materials engineering.