Download or read book Dual beam Second derivative Tunable Diode laser Infrared Spectroscopy Applied to Trace gas Measurement written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A dual beam diode laser spectrometer has been constructed using off-axis reflective optics. The spectrometer can be amplitude modulated for direct absorption measurements or frequency modulated to obtain derivative spectra. The spectrometer has high throughput, is easy to operate and align, provides good dual beam compensation, and has no evidence of the interference effects that have been observed in diode laser spectrometers using refractive optics. Unpurged, using second derivative techniques, the instrument has measured 108 parts-per-million CO (10 cm absorption cell, atmospheric pressure-broadened) with good signal/noise. With the replacement of marginal instrumental components, the signal/noise should be substantially increased. This instrument was developed to monitor the evolution of decomposition gases in sealed containers of small volume at atmospheric pressure.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1981 with total page 1740 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 Tunable Diode Laser Absorption Spectroscopy for Trace Gas Measurements with High Sensitivity and Low Drift written by Christoph Dyroff and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the mechanical and opto-electronic design of laser spectrometers for measuring two very important atmospheric gases, namely water vapor and its isotopic ratios, and formaldehyde. For measuring water vapor, shot-noise limited sensitivity has been achieved by a careful choice of system components and data processing. For measuring formaldehyde, a selective sample modulation exploiting the Stark effect has been used to greatly improve the sensitivity.
Download or read book Monitoring of Gaseous Pollutants by Tunable Diode Lasers written by R. Grisar and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Photochemistry written by D Bryce-Smith and published by Royal Society of Chemistry. This book was released on 2007-10-31 with total page 665 pages. Available in PDF, EPUB and Kindle. Book excerpt: The breadth of scientific and technological interests in the general topic of photochemistry is truly enormous and includes, for example, such diverse areas as microelectronics, atmospheric chemistry, organic synthesis, non-conventional photoimaging, photosynthesis, solar energy conversion, polymer technologies, and spectroscopy. This Specialist Periodical Report on Photochemistry aims to provide an annual review of photo-induced processes that have relevance to the above wide-ranging academic and commercial disciplines, and interests in chemistry, physics, biology and technology. In order to provide easy access to this vast and varied literature, each volume of Photochemistry comprises sections concerned with photophysical processes in condensed phases, organic aspects which are sub-divided by chromophore type, polymer photochemistry, and photochemical aspects of solar energy conversion. Volume 34 covers literature published from July 2001 to June 2002. Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading authorities in the relevant subject areas, the series creates a unique service for the active research chemist, with regular, in-depth accounts of progress in particular fields of chemistry. Subject coverage within different volumes of a given title is similar and publication is on an annual or biennial basis.
Download or read book Derivative Spectroscopy written by Joseph Dubrovkin and published by Cambridge Scholars Publishing. This book was released on 2020-12-23 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will appeal to both practitioners and researchers in both industrial and university chemical, bio-pharmaceutical, and physical, analytical laboratories, and students specializing in analytical spectroscopy, bio-pharmaceutical analysis, chemometrics, and laser physics. It sums up the results of more than half a century of research in derivative spectroscopy, including numerical differentiation and optical modulation techniques. The bibliography also briefly describes hundreds of derivative spectroscopic (classic optical and laser) and non-spectroscopic (chromatography, electrochemistry, and other) methods in industrial and research laboratories. This book differs from existing studies on the subject in that it offers, for the first time, the big picture of all kinds of spectroscopic and non-spectroscopic derivative methods. Also, the book provides quickly reproducible computer calculations illustrating its significant theoretical statements. As such, it can also serve as a practical guide to lecturers in analytical chemistry, chemometrics, and spectroscopy.
Download or read book Publications written by United States. National Bureau of Standards and published by . This book was released on 1989 with total page 360 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 1988 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Publications of the National Institute of Standards and Technology 1988 Catalog written by Rebecca J. Pardee and published by . This book was released on 1989 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1993 with total page 1074 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1988-11 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optics Index written by and published by . This book was released on 1990 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Plasma Surface Interactions and Processing of Materials written by O. Auciello and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt: An understanding of the processes involved in the basic and applied physics and chemistry of the interaction of plasmas with materials is vital to the evolution of technologies such as those relevant to microelectronics, fusion and space. The subjects dealt with in the book include: the physics and chemistry of plasmas, plasma diagnostics, physical sputtering and chemical etching, plasma assisted deposition of thin films, ion and electron bombardment, and plasma processing of inorganic and polymeric materials. The book represents a concentration of a substantial amount of knowledge acquired in this area - knowledge which was hitherto widely scattered throughout the literature - and thus establishes a baseline reference work for both established and tyro research workers.
Download or read book Photometry Radiometry and Measurements of Optical Losses written by Michael Bukshtab and published by Springer. This book was released on 2019-02-25 with total page 808 pages. Available in PDF, EPUB and Kindle. Book excerpt: The revised 2nd edition of this practical book provides an expanded treatment and comparison of techniques used in advanced optical measurements, guiding its reader from fundamental radiometric and photometric concepts to the state-of-the-art in highly sensitive measurements of optical losses and in spectroscopic detection using coherent laser light and spontaneous radiation. The book describes and compares a broad array of high-sensitivity methods and techniques – from interferometric and/or calorimetric, acousto-optic and resonator or polarization to wavelength- and frequency-modulation, phase-shift and decay time studies, and direct-loss measurements for free-space, fiber- or waveguide-based systems and devices. Updated throughout, the new edition describes novel trends in spectral interferometry, frequency-comb and laser-excitation spectroscopy, reflected in the developments of Raman, Brillouin and FTIR (Fourier Transform Infra-Red) techniques for biomedical research, biotech sensing and detection. It also covers broad practical implementations of time- and frequency-domain terahertz spectroscopy measurements. This book reviews the physical concepts of radiation transfer, providing a quantitative foundation for the means of measurements of optical losses, which affect propagation and distribution of light waves in various media and in diverse optical systems and components. It focuses on the application of optical methods and procedures for the evaluation of transparent, reflecting, scattering, absorbing, and aggregated objects, and for determining the power and energy parameters of radiation and color properties of light. This updated new edition will serve as an up-to-date reference source and practical guide for those using photometric and radiometric techniques.
Download or read book INIS Atomindex written by and published by . This book was released on 1984 with total page 1858 pages. Available in PDF, EPUB and Kindle. Book excerpt:
