Download or read book Infrared Diode Laser Spectroscopy of Transient and Stable Molecules written by W. Lewis-Bevan and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Infrared Diode Laser Spectroscopy of Transient Phosphorus bearing Molecules written by Paul John O'Sullivan and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Introduction to Laser Spectroscopy written by David L. Andrews and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the new edition the editors have preserved the basic concept and structure, with the involvement of some new authors - all recognized experts in laser spectroscopy. Each chapter addresses a different technique, providing a review and analysis of the current status, and reporting some of the latest achievements. With the key formulas and methods detailed in many sections, this text represents a practicable handbook of its subject. It will be a valuable tool both for specialists to keep abreast of developments and for newcomers to the field needing an accessible introduction to specific methods of laser spectroscopy - and also as a resource for primary references.

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 Energetics of Stable Molecules and Reactive Intermediates written by M.E. Minas da Piedade and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covers the major experimental and theoretical methods currently used to study the energetics of stable molecules and reactive intermediates. Reviews the ate of the art and shows the interplay of experimental and theoretical methods used to probe bonding energetics and reactivity and a wide range of chemical species. A modern and invaluable introduction to the study of molecular energetics. A reference for workers currently involved in the field.

Download or read book Absorption Spectroscopy Studies in Low Pressure Non Equilibrium Molecular Plasmas Using Tunable Infrared Diode Lasers written by Frank Hempel and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tunable infrared diode laser absorption spectroscopy (TDLAS) has been applied to investigate the chemical kinetics in reactive discharges. It was used to detect the methyl radical and nine stable molecules, CH4, CH3OH, C2H2, C2H4, C2H6, NH3, HCN, CH2O and C2N2, in H2-Ar-N2 microwave plasmas containing up to 7.2 % of methane or methanol, under both flowing and static conditions. The degree of dissociation of the hydrocarbon precursor molecules varied between 20 and 97 %. The methyl radical concentration was found to be in the range 1012 to 1013 molecules cm-3. By analysing the temporal development of molecular concentrations under static conditions it was found that HCN and NH3 are the final products of plasma chemical conversion. The fragmentation rates of methane and methanol and the respective conversion rates to methane, hydrogen cyanide and ammonia have been determined for different hydrogen to nitrogen concentration ratios. An extensive model of the chemical reactions involved in the H2-N2-Ar-CH4 plasma has been developed. Model calculations were performed by including 22 species, 145 chemical reactions and appropriate electron impact dissociation rate coefficients. The results of the model calculations showed satisfactory agreement between calculated and measured concentrations. The most likely main chemical pathways involved in these plasmas are discussed and an appropriate reaction scheme is proposed. Based on the model calculations the concentrations of non-measured species like CH2 or NH2 have been predicted.In addition, spectroscopic investigations of P- and R-branch lines of the fundamental bands of 12C14N and 13C14N in their ground electronic state have been performed at high resolution by tunable diode laser absorption spectroscopy. The radicals were generated in microwave plasmas containing methane with varying proportions of N2 and H2. From a fit to the spectra the origins of the fundamental bands of the two isotopomers were determined to be 2042.42104(84) cm-1 and 2000.08470(30) cm-1. The main product detected in the plasma was HCN. It showed concentrations which are about three orders of magnitude higher than that of CN.Moreover, the time and spatial dependence of the chemical conversion of CO2 to CO were studied in a closed glow discharge reactor (p = 50 Pa, I = 2 and 30 mA) consisting of a small plasma zone and an extended stationary afterglow. Tunable infrared diode laser absorption spectroscopy has been applied to determine the absolute ground state concentrations of CO and CO2. After a certain discharge time the concentrations of both species were observed to come into equilibrium. The spatial dependence of the equilibrium CO concentration in the afterglow was found to vary by less than 10 %. The feed gas was converted to CO more predominantly between 45 % and 60 % with increasing discharge current. The formation time of the stable gas composition decreased with increasing current too. For currents higher than 10 mA the conversion rate of CO2 to CO was estimated to be 1 x 1013 molecules J-1. Based on the experimental results a model of the CO2 conversion chemistry has also been established for this type of discharge. The calculated and measured temporal developments of species concentrations showed a satisfactory agreement for various discharge currents.Lastly, infrared tunable diode laser absorption spectroscopy has been used to analyse the fragmentation of TiCl4 into HCl in pulsed H2-Ar-N2 dc plasmas (p= 2 mbar). At small TiCl4 admixtures (0.04-0.31 %) HCl concentrations of 2-5 x 1014 molecules cm-3 were measured (current density: 0.6-1.15 mA cm2). A nearly complete conversion of Cl into HCl was found at TiCl4 admixtures below 0.2 %.

Download or read book Infrared Diode Laser Spectroscopy of Transient Species written by N. T. Hunt and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Infrared Laser Specttroscopy of Transient Molecules Including Trifluorovinyl Radical C2F3 written by Brent Ernest Wurfel and published by . This book was released on 1990 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Infrared Diode Laser Spectroscopy of Jet Cooled Molecules written by Anthony Joseph Bednar and published by . This book was released on 1998 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Infrared Diode Laser Spectroscopy of Free Radicals and Molecular Ions written by W. J. M. Rothwell and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Resolution Infrared Spectroscopy of Transient Molecules Development of Broadband Optical Parametric Oscillators written by Jürgen Krieg and published by Cuvillier Verlag. This book was released on 2012-02-13 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: The infrared spectral region between wavelengths of 2 and 6 µm is of great importance in molecular physics. Molecules with an X-H bond (X being carbon, nitrogen or oxygen) exhibit strong vibrational transitions there, but also linear carbon clusters Cn (n=2,3,...). Many combination bands and overtones of low-energy vibrational modes also occur in this spectral range. Analyses of these spectral features allow - if highly resolved - for example the prediction of pure rotational transitions in the sub-mm wavelength regime, or help understanding the internal dynamics of the molecule. To provide radiation sources with extremely large frequency coverage, two optical parametric oscillator (OPO) systems in the wavelength regions from 2.5 to 4.1 µm and from 4.7 to 5.4 µm have been set up and characterized in this thesis. The OPO system around 5 µm wavelength is the only one in this spectral region used in high-resolution spectroscopy up to now. Both of the OPO systems have been shown to be ideal tools for spectroscopic studies delivering highly accurate transition frequencies of transient molecules, using the following example cases: The rovibrational spectrum of the fundamental cation CH2D+ around 3.2 µm wavelength has been measured with unprecedented spectral resolution and frequency accuracy. The combination of the OPO as radiation source with a cold ion trap to produce and store the ions has been proven to have a high predictive power for pure rotational transition frequencies of CH2D+. Located at around 100 to 200 GHz, these are of great importance in astrophysics. The V3 fundamental vibration of Si2C3 around 5.1 µm wavelength has been measured using the OPO and a newly built jet spectrometer for the production of transient molecules. Molecular parameters have been determined with high precision. An associated hot band originating from the V7 vibrational bending mode has been resolved and analyzed for the first time. The pure carbon clusters C3 and C7 have also been examined. For the first time, a combination band of C3 and an associated hot band were detected around 3.0 µm wavelength in the gas phase. Their analyses yield valuable information about the potential energy surface of C3. Analysis of the V5 mode of C7 delivered further proof of its rigidity, which was put into question by earlier works. Last but not least, a previously unknown associated hot band of C7 has been detected and analyzed.

Download or read book High Resolution Infrared Diode Laser Spectroscopy of Jet cooled Polyatomic Molecules and Molecular Clusters written by Marcos Antonio Loroño G. and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Infrared Laser Jet Spectroscopy of Transient Molecules Generated by Flash Pyrolysis written by Raymond Jeremy Livingstone and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Introduction to Complex Plasmas written by Michael Bonitz and published by Springer Science & Business Media. This book was released on 2010-07-29 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: Complex plasmas differ from traditional plasmas in many ways: these are low-temperature high pressure systems containing nanometer to micrometer size particles which may be highly charged and strongly interacting. The particles may be chemically reacting or be in contact with solid surfaces, and the electrons may show quantum behaviour. These interesting properties have led to many applications of complex plasmas in technology, medicine and science. Yet complex plasmas are extremely complicated, both experimentally and theoretically, and require a variety of new approaches which go beyond standard plasma physics courses. This book fills this gap presenting an introduction to theory, experiment and computer simulation in this field. Based on tutorial lectures at a very successful recent Summer Institute, the presentation is ideally suited for graduate students, plasma physicists and experienced undergraduates.

Download or read book Infrared Diode Laser Absorption Spectroscopy of Gas Phase Molecular Ions written by Zhuan Liu 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 Laser Spectroscopy of Highly Vibrationally Excited Molecules written by Vladilen Stepanovich Letokhov and published by CRC Press. This book was released on 2021-07-29 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser spectroscopy has been perfected over the last fifteen years to become a precise tool for the investigation of highly vibrationally excited molecules. Intense infrared laser radiation permits both the multiple-photon resonant excitation and the dissociation of polyatomic molecules. In this book, the latest results of some of the foremost Soviet researchers are published for the first time in the West. Laser Spectroscopy of Highly Vibrationally Excited Molecules contains a comprehensive study of both the experimental and theoretical aspects of the basic photophysical interactions that occur in these processes. The book first focuses on the nonlinear interaction between the resonant vibrational mode and the intense infrared field and then examines the nonlinear interaction between the vibrational modes themselves due to anharmonicity. These interrelated processes determine all the characteristics of polyatomic molecules in an infrared field. The book also discusses related phenomena such as spectra broadening, optical resonance, photon echoes, and dynamical chaos. It includes examples of multiple-photon resonant excitation such as the excitation of OsO4 by CO^O2 laser radiation, which is detected by the visible luminescence that results. This book will be of great interest to researchers and postgraduate students in infrared laser spectroscopy and the laser chemistry of molecules and applications of isotope separation.

Download or read book Spectroscopy Dynamics and Molecular Theory of Carbon Plasmas and Vapors written by Laszlo Nemes and published by World Scientific. This book was released on 2011 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a stop-gap contribution to the science and technology of carbon plasmas and carbon vapors. It strives to cover two strongly related fields: the molecular quantum theory of carbon plasmas and carbon nanostructures; and the molecular and atomic spectroscopy of such plasmas and vapors. These two fields of research are strongly intertwined and thus reinforce one another.Even though the use of carbon nanostructures is increasing by the day and their practical uses are emerging, there is no modern review on carbon plasmas, especially from molecular theoretical and spectroscopic viewpoints. The importance of the present book is therefore great from both educational and practical aspects. This review might be the first step towards bringing such textbooks into existence for university education. Similarly, for applied and engineering works in carbon nanostructures, the book provides a theoretical salient point for technologists in the field.