共查询到20条相似文献,搜索用时 11 毫秒
1.
We employed tunable diode laser absorption spectroscopy to measure the line strength, the methane (CH4), ethane (C2H6) and the propane (C3H8) broadening coefficients for the 523–422 H2O transition at 3619.61 cm?1. Water amount fractions generated by a stable and accurate humidity transfer standard, traceable to the SI units via the German national humidity standard, were used to calibrate the spectroscopic line strength measurements. We focus on the traceability of the measured line data to the SI and on uncertainty assessments following the guidelines of the Guide to the Expression of Uncertainty in Measurement. We determined the line strength to be (8.42 ± 0.07)×10?20 cm?1/(cm?2 molecule) corresponding to a relative uncertainty of ±0.8%. To the best of our knowledge, we report the first methane, ethane and propane broadening coefficients of (8.037 ± 0.056)×10?5 cm?1/hPa, (9.077 ± 0.064)×10?5 cm?1/hPa and (10.469 ± 0.073)×10?5 cm?1/hPa for the 523–422 H2O transition at 3619.61 cm?1, respectively. The relative combined uncertainties of the stated CH4, C2H6 and C3H8 broadening coefficients are in the ±0.7% range. 相似文献
2.
R. Lewicki G. Wysocki A.A. Kosterev F.K. Tittel 《Applied physics. B, Lasers and optics》2007,87(1):157-162
Quartz-enhanced photoacoustic spectroscopy was employed for trace gas concentration measurements of CO2 and NH3 using a continuous wave thermoelectrically cooled, distributed feedback diode laser operating at 2 μm. A normalized noise
equivalent absorption coefficient, NNEA(1σ)=1.4×10-8 cm-1W/ was obtained for CO2 using the R18 line of the 2ν1+ν3 band at 4991.26 cm-1. This corresponds to minimum detection limit (1σ) of 18 parts per million (ppm) for a 1 s lock-in time constant. The influence
of the H2O presence in the sample gas mixture on the CO2 sensor performance was investigated. Ammonia detection was performed using the P
P
6(6)S line of the ν3+ν4 band at 4986.99 cm-1. A detection limit (1σ) of 3 ppm for NH3 concentration with a 1 s lock-in time constant was achieved. This results in a normalized noise equivalent absorption of
NNEA(1σ)=8.9×10-9 cm-1W/.
PACS 82.80.Kq; 46.62.Fi; 42.55.Px 相似文献
3.
M. Fukuda T. Mishima N. Nakayama T. Masuda 《Applied physics. B, Lasers and optics》2010,100(2):377-382
The factors determining temperature and current coefficients of lasing wavelength are investigated and discussed under monitoring
CO2-gas absorption spectra. The diffusion rate of Joule heating at the active layer to the surrounding region is observed by
monitoring the change in the junction voltage, which is a function of temperature and the wavelength (frequency) deviation
under sinusoidal current modulation. Based on the experimental results, the time interval of monitoring the wavelength after
changing the ambient temperature or injected current (scanning rate) has to be constant at least to eliminate the monitoring
error induced by the deviation of lasing wavelength, though the temperature and current coefficients of lasing wavelength
differ with the rate. 相似文献
4.
C. Corsi M. Inguscio S. Chudzynski K. Ernst F. D’Amato M. De Rosa 《Applied physics. B, Lasers and optics》1999,68(2):267-269
Sensitivity studies are also performed, to evaluate the minimum detectable concentration of HCl in air.
Received: 7 August 1998/Revised version: 5 October 1998 相似文献
5.
6.
P. Kluczynski M. Jahjah L. N?hle O. Axner S. Belahsene M. Fischer J. Koeth Y. Rouillard J. Westberg A. Vicet S. Lundqvist 《Applied physics. B, Lasers and optics》2011,105(2):427-434
Using recently developed GaInAsSb/AlGaInAsSb DFB lasers, tunable diode laser spectroscopy (TDLS) has been extended into the 3-??m wavelength region for the detection of acetylene impurities in hydrocarbon compounds encountered in ethylene manufacturing. Measurements of acetylene in pure polymer grade ethylene and in a gas mixture of ethylene and ethane typical of the process stream around a hydrogenation reactor have been performed. Using a procedure incorporating subtraction of a hydrocarbon background spectrum a detection limit of 5?ppb?m was achieved under ordinary laboratory conditions. Under forced temperature cycling conditions, the detection limit deteriorated to 180 ppb?m, due to temperature drift caused by optical interferences generated by reflections in the laser TO8 can. 相似文献
7.
The room temperature operating GaInAsSb/AlGaAsSb based diode laser and 66 K InAsSb/InAsSbP laser diode both operating in spectral range of formaldehyde absorption 4350-4361 cm−1 and 2821-2823 cm−1 have been characterized and compared. Very precise arrangement of laser absorption together with high resolution Fourier transform technique was tested. The photoacoustic technique was employed to determine the detection limit of formaldehyde (less than 1 ppmV) diluted by nitrogen for the strongest absorption line of the ν3 + ν5 band in the emission region of the GaInAsSb/AlGaAsSb diode laser. The detection limit (less than 10 ppbV) of formaldehyde was achieved in the 2820 cm−1 spectral range in case of InAsSb/InAsSbP laser (fundamental bands of ν1, ν5). 相似文献
8.
Simultaneous measurement of liquid water film thickness and vapor temperature using near-infrared tunable diode laser spectroscopy 总被引:1,自引:0,他引:1
A fiber-based multiplexed tunable diode-laser absorption sensor with three near-infrared distributed-feedback diode lasers
at ∼1.4 μm is used for simultaneous nonintrusive measurements of liquid water film thickness and vapor-phase temperature.
Water film thicknesses are derived from broad-band absorption determined at two fixed wavelengths while gas-phase temperature
above the film is obtained via two-line thermometry using the fast wavelength tuning with line-integrating absorption. Probing
the liquid film at two wavelengths with significantly different liquid-phase absorption cross sections allows discriminating
against additional signal losses due to surface fowling, reflection, and beam steering. The technique is demonstrated for
liquid layers of defined thicknesses and in time-resolved measurements of evaporating films. 相似文献
9.
E. A. Arbabzadah C. C. Phillips M. J. Damzen 《Applied physics. B, Lasers and optics》2013,111(2):333-339
A study is made of a diode pumped Er3+:YSGG laser crystal operating at 2.797 μm. Lasers were constructed in the bounce geometry, using a transversely cooled 50 at.% Er:YSGG slab and a face-cooled 38 at.% Er:YSGG slab. Results from these are compared with those from a 50 at.% Er3+:YAG laser, also in the bounce geometry. With quasi-continuous wave diode pumping, free-running pulse energies of up to ~55 mJ and a slope efficiency of 20.5% are obtained from 50 at.% Er:YSGG. Better thermal performance is obtained from the face-cooled 38 at.% Er:YSGG slab, allowing average power of ~2 W to be obtained at a repetition rate and pump pulse duration of 140 Hz and 500 μs, respectively. Both Er:YSGG systems perform better than Er:YAG. Numerical modelling of the free-running 50 at.% Er:YSGG and Er:YAG systems is undertaken with good qualitative agreement with experimental results. Electro-optic Q-switching of the 50 at.% Er:YSGG laser using a LiNbO3 crystal yields ~0.5 mJ pulses with ~77 ns duration. 相似文献
10.
《Journal of Molecular Spectroscopy》1987,124(1):99-117
The complexities apparent in the laser Stark spectra obtained from the 10-μm band system of CH2NH are shown to be due to the interplay of the a and b components of the Coriolis and Stark effect coupling. As a result it has been possible to determine the relative orientations of the a and b components of the permanent electric dipole moment. This is analogous to the determination of the relative signs of the dipole moment derivatives from the analysis of the intensity perturbations produced by Coriolis interaction.A detailed comparison has also been made of the uses of laser Stark, diode laser, and Fourier transform spectroscopy for studying heavily perturbed molecular spectra. 相似文献
11.
N. Ibrahim J. Orphal 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(15):2523-2536
The absorption spectrum of H2O has been extensively studied over the past decades in the near-infrared and visible regions, but there remain significant discrepancies in the 10,000-12,500 cm−1 range even for the most intense lines. We have studied 24 lines of H2O using an external-cavity diode laser emitting in the 810-830 nm range, in order to measure absolute line intensities as well as air- and self-broadening coefficients. Comparisons were made with values obtained from the HITRAN database and also with other parameters from recent experiments or predicted calculations. It is suggested that neglecting the effects of H2O collisional narrowing in radiative transfer calculations of the Earth's atmosphere may have a small but significant impact on the radiative budget of the Earth. 相似文献
12.
A compact, diode-based difference-frequency laser system combined with a photoacoustic detection scheme is presented for trace-gas
sensing. It features a broad, continuous tuning range (3.2–3.7 μm), a narrow line width (154 MHz), and room-temperature operation,
and thus allows numerous gas species to be measured both isolated and in mixtures of different gases. Several trace-gas species
of environmental interest were detected, and gas mixtures were analysed. The detection limits are in the low-ppmV range, e.g.
1.3 ppmV for methane, 1.8 ppmV for ethane, and 1.2 ppmV for hydrogen chloride.
Received: 10 April 2002 / Revised version: 5 June 2002 / Published online: 12 September 2002
RID="*"
ID="*"Corresponding author. Fax: +41-1/633-1077, E-mail: Sigrist@iqe.phys.ethz.ch 相似文献
13.
D. Barat J. Angellier A. Vicet Y. Rouillard L. Le Gratiet S. Guilet A. Martinez A. Ramdane 《Applied physics. B, Lasers and optics》2008,90(2):201-204
We report on Fabry–Pérot semiconductor lasers and single frequency distributed feedback lasers based on GaInAsSb/AlGaAsSb
quantum wells. The laser structures were grown by molecular beam epitaxy on GaSb substrates. The devices were etched either
by wet process or by inductively coupled plasma (ICP) process. Electron-beam lithography was used to deposit a metal Bragg
grating on each side of the laser ridge to fabricate the DFB lasers. The devices all operate in the continuous wave regime
at room temperature with a single frequency emission above 2.6 μm and good tuning properties, making them well adapted to
tunable diode laser absorption spectroscopy.
PACS 42.55.Px; 42.62.Fi 相似文献
14.
Elisabetta Canè Mattia Villa Riccardo Tarroni Andrea Pietropolli Charmet Nicola Tasinato 《Molecular physics》2014,112(14):1899-1909
The v4 fundamental band of CF379Br and CF381Br, present in natural isotopic abundance, was investigated in the 8.3-μm region by high-resolution infrared spectroscopic techniques. Tuneable diode laser spectra were recorded in the ranges 1202.5–1205.0 cm?1, 1208.0–1210.1 cm?1 and 1212.5–1214.5 cm?1. The tuneable diode laser spectra were obtained at the reduced temperature of 200 K and in a free-jet expansion. The latter technique was used to reduce spectral congestion, achieving a rotational temperature of about 50 K, with a resolution up to 0.0008 cm?1. A Fourier transform infrared spectrum covering the entire spectral region of the v4 band, between 1190 and 1220 cm?1, was recorded at 298 K with a resolution of 0.004 cm?1. The experimental wavenumbers from the different spectroscopic techniques were combined to accomplish the complete ro-vibrational analysis of v4. In total, 4651 transitions were assigned to CF379Br, 4047 to CF381Br, with J″max? = K″max?=80; of these, 3171 for CF379Br and 2755 for CF381Br are from diode laser measurements. The data of each isotopologue were analysed using the model Hamiltonian for a degenerate vibrational state of a molecule of C3v symmetry. The v4 band of both the isotopologues resulted essentially unperturbed, but the Δl = Δk = ±2 l-resonance was found to be active within the v4 = 1 state. Precise values of the vibrational energy and of the ro-vibrational parameters of v4 = 1 for CF379Br and CF381Br were obtained. The bromine isotopic splitting amounts to 6.9 × 10?3 cm?1. In addition, the equilibrium geometry and the harmonic force field were calculated ab initio using the large-size basis set def2-QZVP in conjunction to the PBE0 functional. 相似文献
15.
Franck Bielsa Khelifa Djerroud Albane Douillet Tristan Valenzuela Christophe Daussy Anne Amy-Klein 《Journal of Molecular Spectroscopy》2008,247(1):41-46
We report on highly accurate absolute frequency measurement against a femtosecond frequency comb of six saturated absorption lines of formic acid (HCOOH) with an accuracy of 1 kHz. We also report the frequency measurement of 17 other lines with an accuracy of 2 kHz. Those lines are in quasi coincidence with the 9R(36) to 9R(42) CO2 laser emission lines and are probed either by a CO2 or a widely tunable quantum cascade laser phase locked to a master CO2 laser. The stability of HCOOH stabilized lasers is characterized by a fractional Allan deviation of 3.1 × 10−12 τ−1/2. They give suitable frequency references for Doppler-free two-photon spectroscopy. 相似文献
16.
2 laser. After excitation, the laser power is turned off for a short time and the subsequent decay of the radiation stored
in the cavity is observed via detection of the light leaking out through one of the cavity mirrors. Measurement of the decay
time allows one to determine the photon losses und thus to detect weakly absorbing species inside the cavity. Since the cavity
is frequency-locked to the laser the decay time can be probed with a high repetition rate, basically limited by the sampling
rate of the analog-to-digital converter. This approach is closely related to cavity ring-down spectroscopy with pulsed lasers,
but exhibits several advantages concerning spectral resolution and detection sensitivity. As a practical example we demonstrate
monitoring of trace amounts of ethylene. Using R=99.5% mirrors we achieve a detection limit of 1 ppb ethylene (integration
time: 100 s) corresponding to absorption losses of 3×10-8 /cm. Further improvement is feasible when mirrors with higher reflectivity become available.
Received: 2 July 1998 相似文献
17.
B. Grouiez V. Zeninari L. Joly B. Parvitte 《Applied physics. B, Lasers and optics》2010,100(2):265-273
Pulsed quantum-cascade-laser spectrometers are usually used to detect atmospheric gases with either the interpulse technique
(short pulses, typically 5–20 ns) or the intrapulse technique (long pulses, typically 500–800 ns). Each of these techniques
has its drawbacks. Particularly the gas absorption spectra are generally distorted. We have previously developed another technique
called intermediate-size pulses (typically 50–100 ns) technique for gas detection using pulsed QCL spectrometers. In this
paper, infrared spectra of ammonia recorded with this technique in the 10 μm region are presented. For the NH3 spectra recorded at low pressure (i.e. in the mbar range), the spectra show typical oscillations after the absorption. The
Beer–Lambert law cannot explain these oscillations, termed the rapid-passage effect. Comparisons between experimental and
calculated spectra will be realized. This phenomenon is not satisfactory from a spectroscopic point of view and spectra must
be recorded at higher pressures. For the NH3 spectra recorded at higher pressure (i.e. in the 50 mbar range), the oscillations disappear and the Beer–Lambert law could
be reused. This paper will demonstrate that the intermediate-size technique gives reliable measurements for NH3 detection. Moreover the typical apparatus function (0.003 cm−1 HWHM) is far lower from the typical apparatus function of the interpulse QCL spectrometers (0.015 cm−1 HWHM). 相似文献
18.
G. Durry N. Amarouche L. Joly X. Liu B. Parvitte V. Zéninari 《Applied physics. B, Lasers and optics》2008,90(3-4):573-580
The 2.7 μm spectral range is highly suitable for the in situ monitoring of atmospheric H2O using compact balloonborne laser diode spectrometers. Water vapour spectroscopic parameters of the 202
101 and the 413
414 transitions of the ν3 band are revisited in this spectral region using a new distributed-feedback InGaAsSb laser diode emitting at 2.63 μm. Accurate
line strengths are provided which are well adapted for the in situ probing of the middle atmosphere. Our measurements are
thoroughly compared to an existing molecular database, laboratory measurements and ab-initio calculations. A laser hygrometer
was developed for operation from small stratospheric balloons using this new laser diode technology, with emission at 2.6 μm.
The realized sensor is described and results from a recent test-flight are reported.
PACS 07.57.Ty; 92.60 Jq 相似文献
19.
Hongming Yi Weidong Chen Aurore Vicet Zhensong Cao Xiaoming Gao Tong Nguyen-ba Mohammad Jahjah Yves Rouillard Lars Nähle Marc Fischer 《Applied physics. B, Lasers and optics》2014,116(2):423-428
This paper reports on the development of a gas sensor involving a newly available 3.38-μm distributed feedback laser in combination with a novel T-shape microresonator-based quartz-enhanced photoacoustic spectroscopy (T-mR QEPAS), capable of simultaneous monitoring of multi-species (such as CH4, H2CO, HCl, C2H4) using the same QEPAS spectrophone. As a first demonstration, monitoring of ambient methane (CH4) was achieved at atmospheric pressure with a 1σ detection limit of 400 ppbv (parts per billion by volume) in an integration time of 10 s and a water vapor concentration of 1.15 vol% (11,500 ppm) in the atmosphere, which is very suitable for field measurement of CH4 emission. 相似文献