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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Database Needs for Modeling and Simulation of Plasma Processing written by National Research Council and published by National Academies Press. This book was released on 1996-10-21 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: In spite of its high cost and technical importance, plasma equipment is still largely designed empirically, with little help from computer simulation. Plasma process control is rudimentary. Optimization of plasma reactor operation, including adjustments to deal with increasingly stringent controls on plant emissions, is performed predominantly by trial and error. There is now a strong and growing economic incentive to improve on the traditional methods of plasma reactor and process design, optimization, and control. An obvious strategy for both chip manufacturers and plasma equipment suppliers is to employ large-scale modeling and simulation. The major roadblock to further development of this promising strategy is the lack of a database for the many physical and chemical processes that occur in the plasma. The data that are currently available are often scattered throughout the scientific literature, and assessments of their reliability are usually unavailable. Database Needs for Modeling and Simulation of Plasma Processing identifies strategies to add data to the existing database, to improve access to the database, and to assess the reliability of the available data. In addition to identifying the most important needs, this report assesses the experimental and theoretical/computational techniques that can be used, or must be developed, in order to begin to satisfy these needs.
Download or read book Journal of Research of the National Bureau of Standards written by United States. National Bureau of Standards and published by . This book was released on 1988 with total page 784 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Low Temperature Plasma Physics written by R. Hippler and published by Wiley-VCH. This book was released on 2001-06-18 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-temperature plasma physics is a very active area of research located on the boundaries between physics, chemistry and materials science. Recent technological developments, e.g. in plasma etching or plasma deposition, have led to a revived interest in plasma physics and technology. This volume describes in detail fundamentals and applications of low-temperature plasma physics including newest achievements. The authors of this volume are top scientists from the USA and Europe who present most recent successes in our understanding of how plasmas behave and put a strong focus on the links between theory and experiment or technological process.
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 Handbook of Thermal Plasmas written by Maher I. Boulos and published by Springer Nature. This book was released on 2023-02-20 with total page 1973 pages. Available in PDF, EPUB and Kindle. Book excerpt: This authoritative reference presents a comprehensive review of the evolution of plasma science and technology fundamentals over the past five decades. One of this field’s principal challenges has been its multidisciplinary nature requiring coverage of fundamental plasma physics in plasma generation, transport phenomena under high-temperature conditions, involving momentum, heat and mass transfer, and high-temperature reaction kinetics, as well as fundamentals of material science under extreme conditions. The book is structured in five distinct parts, which are presented in a reader-friendly format allowing for detailed coverage of the science base and engineering aspects of the technology including plasma generation, mathematical modeling, diagnostics, and industrial applications of thermal plasma technology. This book is an essential resource for practicing engineers, research scientists, and graduate students working in the field.
Download or read book Publications of the National Bureau of Standards Catalog written by United States. National Bureau of Standards and published by . This book was released on 1980 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nonthermal Plasma Chemistry and Physics written by Jurgen Meichsner and published by CRC Press. This book was released on 2012-11-13 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt: In addition to introducing the basics of plasma physics, Nonthermal Plasma Chemistry and Physics is a comprehensive presentation of recent developments in the rapidly growing field of nonthermal plasma chemistry. The book offers a detailed discussion of the fundamentals of plasma chemical reactions and modeling, nonthermal plasma sources, relevant diagnostic techniques, and selected applications. Elucidating interconnections and trends, the book focuses on basic principles and illustrations across a broad field of applications. Expert contributors address environmental aspects of plasma chemistry. The book also includes selected plasma conditions and specific applications in volume plasma chemistry and treatment of material surfaces such as plasma etching in microelectronics, chemical modification of polymer surfaces and deposition of functional thin films. Designed for students of plasma physics, Nonthermal Plasma Chemistry and Physics is a concise resource also for specialists in this and related fields of research.
Download or read book Application of Tunable Diode and Other Infrared Sources for Atmospheric Studies and Industrial Process Monitoring II written by Alan Fried and published by SPIE-International Society for Optical Engineering. This book was released on 1999 with total page 276 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 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 1991 with total page 480 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 30th Aerospace Sciences Meeting and Exhibit 92 0670 92 0719 written by and published by . This book was released on 1992 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Publications written by United States. National Bureau of Standards and published by . This book was released on 1980 with total page 668 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 1990 with total page 1266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cumulated Index Medicus written by and published by . This book was released on 1994 with total page 1416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
