Download or read book High Resolution Infrared Spectroscopic Studies of Molecular Ions Using Tunable Diode Lasers written by Di-Jia Liu and published by . This book was released on 1987 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 High Resolution Infrared Spectroscopy of Molecular Ions Using a Difference Frequency Laser Spectrometer written by Brent David Rehfuss and published by . This book was released on 1990 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Infrared Laser Spectroscopy of Molecular Ions written by Mark Leon Polak and published by . This book was released on 1990 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Infrared Laser Spectroscopy of Molecular Ions and Clusters written by Martin Gruebele and published by . This book was released on 1988 with total page 400 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 Handbook of High resolution Spectroscopy written by Martin Quack and published by John Wiley & Sons. This book was released on 2011-09-26 with total page 2236 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of High-Resolution Spectroscopy has been considerably extended and even redefined in some areas. Combining the knowledge of spectroscopy, laser technology, chemical computation, and experiments, Handbook of High-Resolution Spectroscopy provides a comprehensive survey of the whole field as it presents itself today, with emphasis on the recent developments. This essential handbook for advanced research students, graduate students, and researchers takes a systematic approach through the range of wavelengths and includes the latest advances in experiment and theory that will help and guide future applications. The first comprehensive survey in high-resolution molecular spectroscopy for over 15 years Brings together the knowledge of spectroscopy, laser technology, chemical computation and experiments Brings the reader up-to-date with the many advances that have been made in recent times Takes the reader through the range of wavelengths, covering all possible techniques such as Microwave Spectroscopy, Infrared Spectroscopy, Raman Spectroscopy, VIS, UV and VUV Combines theoretical, computational and experimental aspects Has numerous applications in a wide range of scientific domains Edited by two leaders in this field Provides an overview of rotational, vibration, electronic and photoelectron spectroscopy Volume 1 - Introduction: Fundamentals of Molecular Spectroscopy Volume 2 - High-Resolution Molecular Spectroscopy: Methods and Results Volume 3 - Special Methods & Applications
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 High Resolution Infrared Laser Spectroscopy written by Sze-Tsen Lee and published by . This book was released on 1991 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Infrared Spectroscopy of Weakly Bound Molecular Ions written by Lisa I-Ching Yeh and published by . This book was released on 1988 with total page 392 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 Postdoctoral Research Associateships written by and published by . This book was released on 1986 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laser Photodissociation and Spectroscopy of Mass separated Biomolecular Ions written by Nicolas C. Polfer and published by Springer Science & Business Media. This book was released on 2013-09-03 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: This lecture notes book presents how enhanced structural information of biomolecular ions can be obtained from interaction with photons of specific frequency - laser light. The methods described in the book "Laser photodissociation and spectroscopy of mass-separated biomolecular ions" make use of the fact that the discrete energy and fast time scale of photoexcitation can provide more control in ion activation. This activation is the crucial process producing structure-informative product ions that cannot be generated with more conventional heating methods, such as collisional activation. The book describes how the powerful separation capabilities and sensitivity of mass spectrometry (MS) can be combined with the structural insights from spectroscopy by measuring vibrational and electronic spectra of trapped analytes. The implementation of laser-based photodissociation techniques in MS requires basic knowledge of tunable light sources and ion trapping devices. This book introduces the reader to key concepts and approaches in molecular spectroscopy, and the light sources and ion traps employed in such experiments. The power of the methods is demonstrated by spectroscopic interrogation of a range of important biomolecular systems, including peptides, proteins, and saccharides, with laser light in the ultraviolet-visible, and infrared range. The book "Laser photodissociation and spectroscopy of mass-separated biomolecular ions" is an indispensable resource for students and researchers engaged or interested in this emerging field. It provides the solid background of key concepts and technologies for the measurements, discusses state-of-the-art experiments, and provides an outlook on future developments and applications.
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 Infrared Spectroscopic and Kinetic Studies of Molecular Ions and H2 in Glow Discharges with a Difference Frequency Laser System written by Dairene K. Uy and published by . This book was released on 1996 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Laser Spectroscopy written by Wolfgang Demtröder and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the lectures and seminars presented at the NATO Advanced Study Institute on "Applied Laser Spectroscopy" the fourteenth course of the Europhysics School of Quantum Electronics, held under the supervision of the Quantum Electronics Division of the European Physical Society. The Institute was held at Centro "I Cappuccini", San Miniato, Tuscany, Italy, September 3-15,1989. The Europhysics School of Quantum Electronics was started in 1970 with the aim of providing instruction for young researchers and advanced students already engaged in the area of quantum electronics or wishing to switch to this area from a different background. Presently the school is under the direction of Professors F.T. Arecchi and M Inguscio, University of Florence and Prof. H. Walther University of Munich and has the headquarters at the National Institute of Optics (INO), Firenze, Italy. Each time the directors choose a subject of particular interest, alternating fundamental topics with technological ones, and ask colleagues specifically competent in a given area to take the scientific responsibility for that course.
Download or read book Infrared Spectroscopy of Molecular Clusters written by Martina H. Havenith and published by Springer. This book was released on 2003-07-01 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is intended to give an introduction to intermolecular forces from an experimental point of view. Within the last 10 years the interest has turned more and more into an understanding of the weak, but important, int- molecular forces. New experimental techniques have been developed which have helped to gain more insight into this interesting topic. This book is intended as an introduction for graduate students who are familiar with the main concepts of n~olecular spectroscopy. Special emphasis will be laid on the theoretical concepts. After a detailed description of experimental techniques, the results for two prototype systems which have been the subject of several studies in the literature within recent years will be presented. Ar-CO is becoming the most extensively studied van der Waals complex, theoretically and experimentally. Nevertheless, this example shows that even though the theory has greatly improved and has helped us to improve our knowledge of intermolecular forces, even for relatively simple cases the theory car1 still fall short of an accurate description. For a long time (NH3)2 was considered as a prototype for hydrogen bo- ing. However, subsequent experimental and theoretical studies have revealed the mysteries of the obtained spectra and proved that our previous concept of hydrogen bonds was just too naive.
