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We present the first photoacoustic spectrometer for gas sensing employing both the fundamental and the frequency-doubled radiation
of a continuously tunable high-pressure CO2 laser with room temperature operation. A quasi-phase-matched diffusion-bonded GaAs crystal is used in the system for second-harmonic
generation. A pulsed photoacoustic detection scheme with a non-resonant cell, equipped with an 80-microphone array, is employed.
The wide continuous tuning range in the fundamental (9.2–10.7 μm) and the frequency-doubled (4.6–5.35 μm) regimes, together
with the narrow linewidth of 540 MHz (0.018 cm-1) for the 10-μm region and of 1050 MHz (0.0315 cm-1) for the 5-μm region, allow the measurement of gas mixtures, individual species and isotope discrimination. This is illustrated
with measurements on NO and CO2. The measured isotope ratio 15
NO/14
NO=(3.58±0.55)×10-3 agrees well with the literature (3.700×10-3) and demonstrates the good selectivity of the system.
Received: 30 April 2002 / Revised version: 10 June 2002 / Published online: 2 September 2002
RID="*"
ID="*"Corresponding author. Fax: +41-1/633-1077, E-mail: sigrist@iqe.phys.ethz.ch 相似文献
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High resolution spectral data of 100 ppmV (10(-6) per volume) concentrations of the trace gases bromo methane (BM, CH3Br), and methyl bromide (DME, (CH3)2O), buffered in synthetic air (80% N2, 20% O2) at atmospheric pressure and room temperature are reported. The spectra are recorded with a continuously tunable 10-bar CO2 laser based photoacoustic (PA) spectrometer. The tuning range covers 76 cm(-1) between 9.2 microm (1087 cm(-1)) and 10.7 microm (935 cm(-1)) at a constant narrow line-width of 0.018 cm(-1) (540 MHz). The non-resonant PA measuring cell employs an in-line 10-microphone array. The estimated detection limits for BM and DME are approximately 2 ppmV for a signal-to-noise ratio (SNR) of 3. This corresponds to a calculated detection limit of approximately 76 ppbV for ethylene. 相似文献
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Zn(ClO4)2 aqueous solution–based Zn thin foil|carbon cloth two-electrode single-cell characteristics
Eskusson Jaanus Thomberg Thomas Romann Tavo Lust Karmen Lust Enn Jänes Alar 《Journal of Solid State Electrochemistry》2021,25(12):2869-2880
Journal of Solid State Electrochemistry - Asymmetrical Zn thin foil|carbon cloth two-electrode cells based on 1 M Zn(ClO4)2 aqueous solution have been tested using cyclic voltammetry,... 相似文献
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E. Härk R. Jäger I. Tallo U. Joost P. Möller T. Romann R. Kanarbik V. Steinberg K. Kirsimäe E. Lust 《Journal of Solid State Electrochemistry》2017,21(7):2079-2090
Influence of chemical composition of the ionomers (polyvinyl alcohol (PVA) or Nafion®) on the oxygen reduction reaction (ORR) kinetics has been studied. The 5 wt% Nafion-Vulcan showed higher electrochemical activity toward ORR compared with that for the 5 wt% PVA-Vulcan. Four different Nafion® amounts were used to intermixing a carbide-derived carbon (CDC) or Pt-modified CDC catalysts and the highest electrochemical activity toward ORR was established for the 30 wt% Nafion-Pt/CDC catalyst. Influence of the different amounts of Nafion® ionomer in the catalyst is moderate compared to the effect of variation of the carbon support (Vulcan vs. CDC) or the ionomer (PVA vs. Nafion®). The Randles–?evcik relationship was used to estimate the effective electrochemical active surface area (S eff) of the electrodes, depending on the chemical composition of the ionomer studied. 相似文献
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Pikma Piret Ers Heigo Siinor Liis Zhao Jinfeng Oll Ove Romann Tavo Grozovski Vitali Siimenson Carolin Väärtnõu Mart Paalo Maarja Härmas Riinu Lust Karmen Thomberg Thomas Jänes Alar Nerut Jaak Jäger Rutha Valk Peeter Kivi Indrek Maide Martin Möller Priit Kanarbik Rait Nurk Gunnar Lust Enn 《Journal of Solid State Electrochemistry》2023,27(7):1547-1591
The electrochemistry nowadays has many faces and challenges. Although the focus has shifted from fundamental electrochemistry to applied electrochemistry, one needs to acknowledge that it is impossible to develop and design novel green energy transition devices without a comprehensive understanding of the electrochemical processes at the electrode and electrolyte interface that define the performance mechanisms. The review gives an overview of the systematic research in the field of electrochemistry in Estonia which reflects on the excellent collaboration between fundamental and applied electrochemistry.
相似文献7.
Automatic alignment of a rigid spacer cavity 总被引:2,自引:0,他引:2
Albert?Romann David?S.?Rabeling Glenn?de?Vine Jong?H.?Chow Malcolm?B.?Gray David?E.?McClellandEmail author 《General Relativity and Gravitation》2005,37(9):1591-1599
A bench-top auto-alignment system employing an invariant Gouy phase telescope is described in this paper. Our system uses
external galvanometer-actuated mirrors for the tilt and offset control of a laser beam onto a rigid spacer cavity. Wavefront
sensing diagnostics which accurately decouple tilt and offset er-rors are employed, and corresponding orthogonal corrections
are enabled with the aid of electronic nulling. The closed loop system achieves an alignment fluctua-tion suppression of 50.4
dB for angular tilt and 58.3 dB for lateral offset at 1 Hz, with a unity gain bandwidth in excess of 115 Hz. 相似文献
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Bram?J.?J.?SlagmolenEmail author Mark?Barton Conor?Mow-Lowry Glenn?de?Vine David?S.?Rabeling Jong?H.?Chow Albert?Romann Chunnong?Zhao Malcolm?B.?Gray David?E.?McClelland 《General Relativity and Gravitation》2005,37(9):1601-1608
In this paper we report on the alignment locking of an in vacuum 77 m long suspended mirror Fabry-Perot cavity. Lock was achieved
by mode-matching a 500 mW Nd:YAG NPRO onto a pre-mode cleaner, the output of which was then mode-matched to the suspended
cavity. The longitudinal locking was achieved by feeding back to the laser frequency actuator to follow the cavity resonance.
Subsequent implementation of a hybrid auto-alignment system enhanced the stability of the circulating power inside the cavity.
Preliminary results are presented. 相似文献
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Nguyen Huy Quí Vinh Nerut Jaak Kasuk Heili Härmas Meelis Valk Peeter Romann Tavo Koppel Miriam Teppor Patrick Aruväli Jaan Korjus Ove Volobujeva Olga Lust Enn 《Journal of Solid State Electrochemistry》2023,27(1):313-326
Journal of Solid State Electrochemistry - Novel platinum-ceria-Ketjenblack carbon bifunctional electrocatalysts with flower-shaped ceria crystals were synthesised for conducting the methanol... 相似文献
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