Download or read book High Resolution Wavelength Modulation Spectroscopy for Precise Gaseous Characterization written by Audra Michiele Bullock and published by . This book was released on 1997 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Utilization of Multiple Harmonics of Wavelength Modulation Absorption Spectroscopy for Practical Gas Sensing written by Kai Sun and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To meet more rigorous criteria for environmental-unfriendly emissions and to increase energy efficiency, in-situ real-time sensors are needed to optimize the performance of next-generation energy systems. The emergence of high-quality (narrow linewidth, fast tuning capability) tunable diode lasers (TDLs) has enabled the use of wavelength modulation spectroscopy (WMS) for harsh industrial applications. Compared to conventional direct absorption measurements, WMS has the advantage of 10-100 times better detection sensitivity, avoids the need to obtain a zero-absorption baseline, and provides much better isolation from the beam steering, non-absorption transmission loss (e.g., light scattering) or mechanical vibrations. Many models have been developed to interpret the measured WMS signal into absolute absorption. However, most of these models are limited to specific applications by a wide variety of assumptions and approximation most of which deal with the simultaneous intensity and wavelength modulation of injection-current-modulated diode lasers. In this dissertation, two generalized approaches to analyze the WMS absorption signal were developed that account for non-ideal simultaneous intensity modulation of laser output when injection current variation is used for wavelength modulation. The first approach is ideal for wavelength-fixed WMS (the laser mean wavelength is fixed) analysis and the second approach is ideal for wavelength-scanned (the laser mean wavelength is scanned) WMS analysis, and both of them can be used for arbitrary modulation depth, or laser architectures even when severe non-linear intensity modulation occurs simultaneously with wavelength modulation. These new interpretations of WMS absorption signals provide the potential for extended and improved use of WMS for practical gas sensing in a much wider array of applications. The first approach built on earlier work in our laboratory. The analysis of calibration-free, 1f-normalized, WMS-2f absorption signals was extended to higher harmonics (for example 3f, 4f ...) using traditional Fourier analysis. The new approach and procedure developed also accounts for non-ideal wavelength-tuning of the injection-current tuned laser as well as etalon interference from the optical components in the laser line-of-sight (LOS). This approach was validated using measurements of the CO transition of R (11) in the 1st overtone band near 2.3æm in a laboratory cell at room temperature for a range of CO mole fractions (0.21-2.8%) and pressures (5-20atm). For high-pressure gas sensing, wavelength modulation spectroscopy with higher-order harmonic detection (WMS-nf, n> 2) was found to have less influence from the WMS background signals when the selected modulation depth was near the optimal modulation depth for the WMS-2f signal. This WMS approach was then used for measurements in a pilot-scale entrained-flow coal gasifier at the University of Utah. Even though the particulate scattering reduced the laser transmission as much as 99.997%, and pressure broadening at the 18atm (~250psig) operating pressure blended the absorption transitions, successful in-situ rapid-time-resolved 1f-normalized WMS-2f absorption measurements for gas temperature and H2O mole fraction were made. Based on lessons learned during the gasifier measurements at Utah and a desire to eventually develop real-time sensors for long-term monitoring, a second approach for WMS analysis was developed that differs from previous WMS analysis strategies in two significant ways: (1) the measured laser intensity without absorption is used to simulate the transmitted laser intensity with absorption and (2) digital lock-in and low-pass filter software is used to expand both simulated and measured transmitted laser intensities into harmonics of the modulation frequency, WMS-nf (n=1,2,3 ...), avoiding the need for an analytic model of intensity modulation or Fourier expansion of the simulated WMS harmonics. The new method was demonstrated and validated with WMS of H2O dilute in air (1atm, 296K, near 1392nm). WMS-nf harmonics for n=1 to 6 are extracted and the simulations and measurements are found in good agreement for the entire WMS lineshape. This new analysis scheme was applied to monitor the synthesis gas output from an engineering-scale transport reactor coal gasifier at the National Carbon Capture Center. There the pressures ranged up to 15 atm (~220psig) and temperatures up to 650K. Continuous monitoring of moisture level in the gasifier output with 2s time resolution was performed by the TDL sensor for more than 500 hours, including the periods of burner ignition, combustion heating with a propane flame, coal combustion, coal gasification, and reactor shut-down via coal-feed termination. In addition, a novel and rapid approach to determine the collisional linewidth via the WMS signals at different harmonics at the modulation frequency is presented. The peak values of the WMS-nf absorption spectrum near the transition line center are used to infer the absorption lineshape, which is exploited here to extract collision-broadening halfwidth from the ratio of WMS-4f/WMS-2f (or other even harmonics) signals when the mean laser wavelength is tuned to line center. Measurement of the absorption linewidth enables quantitative WMS measurements without the need for a collision-broadening database. Alternatively, when collision-broadened spectral data are available, a WMS-based pressure sensor can be realized, and a demonstration using the 4fpeak/2fpeak ratio gives less than 0.7% difference for the pressure for cell measurements from 100 torr to 753 torr. These new WMS analysis schemes have been validated in near commercial environments and illustrate the potential of their use to develop practical TDL sensors for a wide variety of industrial applications.
Download or read book Resolution of Overlapping Spectra by Wavelength Modulation Spectroscopy written by Audra Michiele Bullock and published by . This book was released on 2000 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectroscopy and Optical Diagnostics for Gases written by Ronald K. Hanson and published by Springer. This book was released on 2016-08-23 with total page 279 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.
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 Trace Analysis of Specialty and Electronic Gases written by William M. Geiger and published by John Wiley & Sons. This book was released on 2013-07-15 with total page 309 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explores the latest advances and applications of specialty and electronic gas analysis The semiconductor industry depends upon a broad range of instrumental techniques in order to detect and analyze impurities that may be present in specialty and electronic gases, including permanent gases, water vapor, reaction by-products, and metal species. Trace Analysis of Specialty and Electronic Gases draws together all the latest advances in analytical chemistry, providing researchers with both the theory and the operating principles of the full spectrum of instrumental techniques available for specialty and electronic gas analysis. Moreover, the book details the advantages and disadvantages of each technique, steering readers away from common pitfalls. Featuring contributions from leading analytical and industrial chemists, Trace Analysis of Specialty and Electronic Gases covers a wide range of practical industrial applications. The book begins with the historical development of gas analysis and then focuses on particular subjects or techniques such as: Metals sampling and ICP-MS analysis Improvements in FTIR spectroscopy Water vapor analysis techniques New infrared laser absorption spectroscopy approaches GC/MS, GC/AED, and GC-ICP-MS techniques Gas chromatography columns Atmospheric pressure ionization mass spectrometry Lastly, the book examines gas mixtures and standards that are critical for instrument calibration. There are also two appendices offering information on fittings and material compatibility. With its thorough review of the literature and step-by-step guidance, Trace Analysis of Specialty and Electronic Gases enables researchers to take full advantage of the latest advances in gas analysis. Although the book's focus is the semiconductor and electronics industry, analytical chemists in other industries facing challenges with such issues as detection selectivity and sensitivity, matrix gas interference, and materials compatibility will also discover plenty of useful analytical approaches and techniques.
Download or read book Applied Optics written by and published by . This book was released on 1997 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Publications of the National Institute of Standards and Technology Catalog written by National Institute of Standards and Technology (U.S.) and published by . This book was released on 1985 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Near infrared Tunable Diode Laser Absorption Spectrometer for Trace Gas Detection written by Iain Fletcher Howieson and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 NBS Special Publication written by and published by . This book was released on 1968 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wavelength modulation Spectroscopy for Measurements of Gas Temperature and Concentration in Harsh Environments written by Gregory Brian Rieker and published by . This book was released on 2009 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wavelength modulation Spectroscopy for Determination of Gas Properties in Hostile Environments written by Christopher S. Goldenstein and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past 40 years, tunable diode laser absorption spectroscopy (TDLAS) sensors have matured into a practical technology for providing non-intrusive, in-situ measurements of gas properties in a number of hostile energy systems. However, the applicability of TDLAS sensors has been limited by a number of fundamental measurement challenges including: beam-steering, non-absorbing transmission losses, interfering emission, line-of-sight non-uniformities, and broad and blended absorption spectra at high pressures. This work presents the development and demonstration of several novel calibration-free wavelength-modulation spectroscopy (WMS) techniques and sensors that enable high-fidelity measurements of gas properties in highly non-uniform gases and high-pressure gases. These WMS techniques are demonstrated with measurements of gas temperature, H2O, pressure, and velocity in two model scramjet combustors and a pulse detonation combustor.
Download or read book Instrument Development for Atmospheric Research and Monitoring written by Jens Bösenberg and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: Jens Bosenberg Max-Planck-Institut fur Meteorologie, Bundesstr. 55, D-20146 Hamburg, Germany TESLAS, which stands for Tropospheric Environmental Studies by Laser Sounding, was formed in November 1987 as a subproject of EUROTRAC to enhance the measurement capabilities for vertical profiling of ozone in the troposphere by means of laser remote sensing. For studies of several atmospheric processes related to the formation and redistribution of photo-oxidants there was a clear need for measuring extended time series with appropriate vertical and temporal resolution. These could not be obtained by conventional in situ techniques, at least not with affordable effort, so remote sensing appeared to be the best way to obtain the required information. At the beginning of the subproject, some Differential Absorption Lidar (DIAL) systems for measuring the vertical distribution of ozone already existed, but their use was restricted to very few laboratories and very few measurement campaigns, since the instruments were highly complex, rather unreliable, and required extensive efforts for maintenance and operation by skilled scientists. In addition, the accuracy of these measurements under a variety of meteorological conditions was not really well established. The main tasks within TESLAS therefore were to develop fully the DIAL-methodology for remote sensing of tropospheric ozone, and to develop instruments which are accurate, reliable, easy to operate, and suitable for field deployment or airborne operation.
Download or read book Application of Spectroscopy in Agricultural Environment and Livestock Breeding written by Leizi Jiao and published by Frontiers Media SA. This book was released on 2023-08-29 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intelligent agriculture is the inevitable trend of future agriculture. As the brain of intelligent agriculture, advanced sensors determine the degree of agricultural environment and crop perception. However, an outstanding problem is the long-standing lack of effective sensing and monitoring tools in agriculture. Most information still relies on time-consuming and complex laboratory analysis and can only be off-line measured. Therefore, in-situ, on-line and sensitive methods for monitoring information about the agricultural environment and crops are urgently needed. With the development of material science, manufacturing technology and spectroscopy, more and more fast and high-precision spectroscopic methods and sensors are applied in the agricultural environment, livestock breeding and crop. Especially with the development of spectral enhancement, image processing and deep learning techniques, the study of the advanced spectroscopic methods to rapidly and precisely detect heavy metals and nutrients in the soil, harmful gas, water pollutant and crop stress will reduce the probability of subjective error judgment and improves agricultural management and production efficiency. Application of spectroscopy in an agricultural environment and livestock breeding is a research topic of Frontiers in Physics that publishes original research on the field of agricultural physics. And the aim of this research topic is to explore novel and groundbreaking spectroscopic methods to rapidly and in-situ detect information about the agricultural environment, livestock breeding and crop stress, which could be beneficial in the development of Intelligent agriculture.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gas Phase NMR written by Karol Jackowski and published by Royal Society of Chemistry. This book was released on 2016-02-09 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the recent NMR studies with the application of gaseous molecules. Among the comprehensively discussed aspects of the area it includes in particular: new multinuclear experiments that deliver spectral parameters of isolated molecules and provide the most accurate values of nuclear magnetic shielding, isotropic spin–spin coupling and relaxation times; advanced, precise and correct theoretical descriptions of spectral parameters of molecules as well as the application of gas-phase NMR measurements to chemical analysis and medicine. The progress of research in these fields is enormous and has rapidly changed our knowledge and understanding of molecular parameters in NMR spectroscopy. For example, accurate studies of the shielding for isolated molecules allow the exact determination of nuclear magnetic dipole moments, the calculated values of spectral parameters can be verified by precise gas-phase NMR measurements, and the application of hyperpolarized noble gases provides excellent MRI pictures of lungs. Aimed at graduates and researchers in spectroscopy, analytical chemistry and those researching the applications of NMR in medicine, this book presents the connections between sophisticated experiments, the theory of magnetic parameters and the exploration of new methods in practice.
