Trace Gas Monitoring by Open-path Tunable Diode Laser Absorption Spectrometer (OP-TDLAS) PDF Download
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Author: University of Victoria (B.C.). Centre for Earth and Ocean Research
Publisher:
ISBN:
Category : Gas lasers
Languages : en
Pages :
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Author: University of Victoria (B.C.). Centre for Earth and Ocean Research
Publisher:
ISBN:
Category : Gas lasers
Languages : en
Pages :
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Author: Iain Fletcher Howieson
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: William Kennedy Landles
Publisher:
ISBN:
Category : Laser spectroscopy
Languages : en
Pages : 312
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Author: Yufei Ma
Publisher: MDPI
ISBN: 3039283987
Category : Technology & Engineering
Languages : en
Pages : 278
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Book Description
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.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Tunable diode laser absorption spectroscopy (TDLAS) is an optical gas sensing technique in which the emission frequency of a laser diode is tuned over a gas absorption line of interest. A fraction of the radiation is absorbed by the sample gas and this can be determined from measurements of initial intensity and the intensity transmitted through the sample. The amount of light absorbed is related to the gas concentration. Additional modulation techniques combined with phase sensitive detection allow detection of very low gas concentrations (several parts per million). The advantages of using TDLAS for trace gas sensing include; fast response times, high sensitivity and high target gas selectivity. However, the sensitivity of many practical TDLAS systems is limited by the formation of unintentional Fabry-Perot interference fringes in the optical path between the source and detector. The spacing between the maxima of these fringes, in particular those generated in gas cells, can be in the same wavelength range as Doppler and pressure-broadened molecular line widths. This can lead to (1) interference fringe signals being mistaken for gas absorption lines leading to false concentration measurements or (2) distortion or complete obscuring of the shape and strength of the absorption line, such that the sensitivity of the instrument is ultimately limited by the fringes. The interference fringe signals are sensitive to thermal and mechanical instabilities and therefore can not be removed by simple subtraction techniques. Methods that have been proposed by previous workers to reduce the effects of interference fringes include careful alignment of optical components and/or mechanically jittering the offending components. In general the alignment of the optical components is critical. This often leads to complex and fragile designs with tight tolerances on optical component alignment, and can therefore be difficult and expensive to maintain in field instruments. This thesis pr.
Author: Christoph Dyroff
Publisher:
ISBN: 9783866443280
Category :
Languages : en
Pages : 142
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Author: R. Grisar
Publisher: Springer
ISBN: 9789400939929
Category : Science
Languages : en
Pages : 184
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By now it has been nearly twenty years since the pioneering studies at the MIT-Lincoln Laboratories, Lexington, USA, demonstrated the unique capabilities of lead salt tunable diode lasers (TDL) for infrared absorption spectroscopy. The progress in the use of TDL instrumentation for a wide variety of scientific applications was described by a great number of papers since, however, comparatively few meetings were specifically devoted to this subject. In 1980 the conference on "High Resolution Infrared Spectroscopy Applications and Developments" at the National Bureau of Standards in Gaithersburg, USA, reviewed the state of the art of tunable diode lasers together with Fourier Transform Spectroscopy and other laser spectroscopic techniques. Three years later in 1983 the SPIE Conference in San Diego, USA, dedicated one meeting to "Tunable Diode Laser Development and Spectroscopy" Applications. It appeared appropriate after a further interval of three years to organize another meeting about this quickly advancing field. In November of 1986 an International Symposium on "Monitoring of Gaseous Pollutants by Tunable Diode Lasers" was organized by and held at the Fraunhofer-Insti tut fuer Physikalische Messtechnik in Freiburg, FRG. The main emphasis of this conference was put on the applications of TDL techniques to the solution of problems of environmental relevance : The measurement of atmospheric trace gases and the monitoring of exhaust gases from automobile and power plant stack emitters. The state of diode laser development and application of TDL instruments to scientific molecular spectroscopy were not directly subjects of the meeting.
Author: Dragan Vujanic
Publisher:
ISBN:
Category : Laser spectroscopy
Languages : en
Pages :
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Author: Yufei Ma
Publisher: Frontiers Media SA
ISBN: 283251412X
Category : Science
Languages : en
Pages : 492
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Author: A. Fried
Publisher:
ISBN:
Category : Air quality
Languages : en
Pages : 11
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Book Description
There has been an ongoing quest for development of ever more sensitive and selective detection methods for studying various gas molecules of atmospheric importance. Both laboratory and ambient studies often require instrumentation capable of measuring ultratrace concentrations of such gases at, and below, the parts-per-billion range. Concurrently, accurate calibration standards, particularly those verified by independent techniques, are also required. The sensitive, selective, and versatile technique of infrared tunable diode laser absorption spectrometry is especially well suited for ultra-trace gas measurements and calibration standards verification. This combination, which is not shared by many other measurement techniques, results from the fact that diode laser spectrometers can be operated in an absolute mode as well as a more sensitive relative mode. In this paper, we discuss these capabilities and present specific examples for the measurement and calibration of ultra-trace levels of the important atmospheric gases nitrogen dioxide (NO2) and hydrochloric acid (HCl). In addition, we further discuss the application of tunable diode laser absorption spectrometry in the verification of NO2 permeation standards using the gas-phase titration reaction between nitric oxide (NO) and ozone (O3).
