Connecticut College, New London, Connecticut usa general Physics Institute, Russian Academy of Sciences, Moscow, Russia
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B10.Optimization of Trace molecule detection using tunable diode lasers. A.I.Nadezhdinskii Natural Sciences Center of A.M.Prokhorov General Physics Institute of RAS Vavilov str.38, 119991 Moscow, Russia Tunable Diode Laser Spectroscopy (TDLS) was demonstrated to be very efficient technique for trace molecule detection. New generation of Diode Lasers (DL) based systems promises mass application in environment protection, medicine, industry, critical situations control, etc. During last decade more than 30 different DL based systems were developed at NSC GPI for particular applications. System optimization approach will be considered taking into account physical properties of all system elements: DL, photo-detector, optical scheme, object of interest, etc. Systems developed can be classified in several groups according to molecular object of interest, width of its spectral peculiarity, optical scheme in use, system operation mode, etc. Some representatives of instruments developed will be described. Optimization of these systems will be discussed taking into account spectral range in use, laser operation mode, signal acquisition strategy, physical origins of sensitivity limitations, etc. B11.Quad Quantum Cascade Laser with Dual Gas Cells for Simultaneous Analysis of Mainstream and Sidestream Cigarette Smoke Randall E. Baren, Milton E. Parrish, Kenneth H. Shafer Philip Morris USA, Research Center, 4201 Commerce Road, Richmond, VA 23234 USA. Charles N. Harward Nottoway Scientific Consulting Corp., P.O. Box 125, Nottoway, VA 23955 USA. A compact, fast response, infrared spectrometer using four pulsed quantum cascade (QC) lasers has been applied to the analysis of gases in mainstream and sidestream cigarette smoke. QC lasers have many advantages over the traditional lead salt lasers, including near-room temperature operation with thermoelectric cooling and single mode operation with improved long-term stability. The new instrument uses two 36 m, 0.3 liter multiple pass absorption gas cells to obtain a time response of 0.1 seconds for the mainstream system and 0.4 seconds for the sidestream system. With this instrument we have measured simultaneously in mainstream and sidestream smoke the concentrations of ammonia, ethylene, nitric oxide, and carbon dioxide. A data rate of 20 Hz provides sufficient resolution to reveal the concentration profiles during each 2-s puff in the mainstream smoke. Different concentration profiles before, during and after the puffs have also been observed for these smoke constituents in the sidestream smoke. Also, simultaneous measurements of CO2 from a non-dispersive infrared analyzer are used to obtain emission ratios of the smoke constituents relative to the amount of CO2 produced during combustion for various types of cigarettes. B12.On Quantitative Detection of Methyl Radicals in Non-Equilibrium Plasmas G. Lombardi1, G. D. Stancu2, F. Hempel2, A. Gicquel1, and J. Röpcke2 1Laboratoire d’Ingénierie des Matériaux et des Hautes Pressions, CNRS UPR 1311 - Université Paris 13 – 99, avenue J.B. Clément, 93430 Villetaneuse, France 2Institut für Niedertemperatur-Plasmaphysik, 17489 Greifswald, Friedrich-Ludwig-Jahn-Str. 19, Germany Carbon containing radicals are of special interest for basic studies and for application in plasma technology. Indeed, the decomposition of hydrocarbons in a variety of Plasma Enhanced Chemical Vapour Deposition (PECVD) processes is of interest because they are used to deposit thin carbon films. The methyl radical (CH3), on which we are going to focus in this paper, is generally accepted to one of the most essential intermediates in hydrocarbon plasmas. For the in situ detection of the CH3 radical, only two approaches are suitable: mass spectroscopy and optical methods. In the first case threshold ionisation mass spectrometry (TIMS) or photo ionisation mass spectrometry (PIMS) are suitable for the detection of radicals. Non-invasive optical methods for detecting the methyl radical are based on absorption spectroscopy either with UV radiation at about 216 nm or in the mid IR near 3100 cm-1 or 606 cm-1. Although in recent years several studies to quantify the methyl concentration in hydrocarbon plasmas have been performed in the ultraviolet and infrared spectral range, never have both spectroscopic approaches been compared directly to verify the applicability of the absorption cross sections or line strengths for the conditions under study. This comparison is of particular importance since the limitations of the validity of the line parameters are directly related to the accuracy of calculated methyl concentrations and in turn to the quality assessment of related plasma chemical modelling. This contribution describes comparative quantitative studies of the methyl radical in non-equilibrium plasmas by absorption spectroscopic methods. Tunable infrared diode laser absorption spectroscopy (TDLAS) at 16.5 m and broadband ultraviolet absorption spectroscopy at 216 nm have both been used to measure the ground state concentrations of the methyl radical in two different types of non-equilibrium microwave plasmas (f= 2.45 GHz), (i) in H2-Ar plasmas of a planar reactor with small admixtures of methane or methanol, at a pressure of 1.5 mbar, and (ii) in H2-CH4 plasmas of a bell jar reactor, at pressures of 25 and 32 mbar under flowing conditions. For the first time, two different optical techniques have been directly compared to verify the available data about absorption cross sections and line strengths of the methyl radical. It was found, that the application of the CH3 absorption cross section of the B(2A1’) X(2A2’’) transition at 216 nm, reported by Davidson et al. 1995 J. Quant. Spectrosc. Radiat. Transfer 53 581, and of the line strength of the Q(8,8) line of the 2 fundamental band at 16.44 m, given by Wormhoudt et al. 1989 Chem. Phys. Lett. 156 47, leads to satisfactory agreement. B13.Multi-component trace gas detection with TDL and resonant photoacoustic technique: application to the methane, ammonia and ethylene system at 1.63 μm M Scotoni 1, A. Rossi 2, L. Ricci 1, G. Demarchi 1,3, D. Bassi 1, S. Iannotta 3 and A. Boschetti 3 - INFM and Dipartimento di Fisica, Università di Trento, I-38050 Trento-Povo, Italy. INFM and Dipartimento di Fisica, Università di Siena, I-53100 Siena, Italy. IFN-CNR Istituto di Fotonica e Nanotecnologie- Sezione ITC di Trento, I-38050 Trento-Povo, Italy At present many chemical-physics processes, due to human activities, are subject to more and more accurate and sensitive controls for environmental quality, process quality or safety reason. Many of these processes can be monitored by non invasive detection of gaseous systems produced (atmospheric pollution, combustion, food preservation, agro-biological processes, breath analysis etc). Detailed understanding of such processes is more and more demanding in real time and high sensitivity detection of many molecular systems at the same time. Infrared radiation spectroscopy can be a valid multi-component detection method, complementary to other well-proven techniques like, for example, mass spectrometry and gas chromatography. A compact multi-component trace gas detector based on high resolution IR spectroscopy has been developed in our laboratory. The apparatus is composed by a 1.57-1.64 µm tunable diode laser coupled with a resonant photoacoustic cell. A region around 1.63 µm, where 2ν3 (methane), ν2+ν3+ν4 (ammonia) and ν5+ν9 (ethylene) bands are present, has been investigated in order to find non overlapped spectral structures useful for selective detection in ambient air with ppm sensitivity. A resonant optical cavity is under test in order to obtain sub-ppm sensitivity. B14.INFRARED AND MILLIMETER-WAVE SPECTRA OF THE 13C16O DIMER: ASSIGNMENT AND PRECISE LOCATION OF ENERGY LEVELS L.Surin1, D.Fourzikov1, B.Dumesh2, G.Winnewisser1, Jian Tang3 and A.R.W.McKellar3 1I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany; 2Institute of Spectroscopy, Russian Academy of Sciences, 142190 Troitsk, Moscow region, Russia. 3Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada The infrared and millimeter-wave spectra of the fully substituted 13-C carbon monoxide dimer, (13C16O)2, have been studied in order to compare the energy levels of this isotope with those of the normal isotope. Such comparison constitutes a subtle probe of the intermolecular potential, proving the reality of the two isomers discovered earlier for (12C16O)2 and clarifying the nature of the tunneling motion. Infrared spectrum has been observed with diode laser spectrometer in the region of the CO stretching vibration, around 2090 cm-1. Over 120 lines have been assigned to transitions involving 49 rotational levels in the excited state and 24 levels in the ground state. The millimeter wave spectrum of (13C16O)2, has been studied for the first time, confirming and extending the infrared study. Eighty-seven transitions in the 77 – 180 GHz region have been assigned and analyzed in terms of a model-independent term value scheme involving 57 rotational levels with J = 0 to 8. The levels can be classified into 7 “stacks” which have symmetry classifications of either A/B+ or A+/B, and K-values of either 0 or 1. The four A+/B stacks have previously not been observed in the infrared study. The energetically lowest of the stacks fixes the tunneling splitting of (13C16O)2 to be 3.769 cm-1, slightly larger than the (12C16O)2 value of 3.731 cm-1. The energy splitting between the ground states of two isomers is 0.877 cm-1 in (12C16O)2, and 1.285 cm-1 in (13C16O)2. Directory: 2003 2003 -> Tr-41. 4-03-05-024 Telecommunications 2003 -> Review of some tsunamis in canada 2003 -> The skill of multi-model seasonal forecasts of the wintertime North Atlantic Oscillation 2003 -> 2930 Kerry Forest Parkway 2003 -> Canadian Interuniversity Sport (cis) Athletes of the Week 2003 -> Senior Airman Jason Plite Hometown 2003 -> Technical announcements: My apologies for the comparison pages; they were 2003 -> Pool Play Round 1 9: 20: 00 am 2003 -> 2004 Division II men's Golf Championships Final Round Results deland, fla 2003 -> Go Figure Edited by Kostya Kennedy and Mark Bechtel 645 Passing yards, an ncaa division II record, by University of Indianapolis quarterback Matt Kohn, in a 59-52 victory over Michigan Tech Download 1.65 Mb. Share with your friends:
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