共查询到20条相似文献,搜索用时 26 毫秒
1.
J. Sato M. Kikukawa S. Yamaguchi M. Endo K. Tei K. Nanri T. Fujioka 《Applied physics. B, Lasers and optics》2009,96(4):741-744
A flexible and portable trace nitrogen dioxide sensor based on cavity ringdown spectroscopy using an optical fiber-coupled
high-finesse cavity was successfully demonstrated. Tailoring the spatial mode matching condition of the core of an optical
fiber and high-finesse external cavity allows for effective optical feedback into an antireflection-coated laser diode for
stable resonant enhancement of the external cavity. The external cavity, which works as a ringdown cavity, could be remotely
located from the light source and receiver section by only a single mode optical fiber. The sensitivity was found to be 1.0×10−7 cm−1 in a compact 1-cm3 ringdown cavity volume. 相似文献
2.
I. Ventrillard-Courtillot E. Sciamma O’Brien S. Kassi G. Méjean D. Romanini 《Applied physics. B, Lasers and optics》2010,101(3):661-669
In the past decade, due to a growing awareness of the importance of air quality and air pollution control, many diagnostic
tools and techniques have been developed to detect and quantify the concentration of pollutants such as NO
x
, SO
x
, CO, and CO2. We present here an Incoherent Broad-Band Cavity-Enhanced Spectroscopy (IBB-CEAS) set-up which uses a LED emitting around
625 nm for the simultaneous detection of NO2 and NO3. The LED light transmitted through a high-finesse optical cavity filled with a gas sample is detected by a low resolution
spectrometer. After calibration of the spectrometer with a NO2 reference sample, a linear multicomponent fit analysis of the absorption spectra allows for simultaneous measurements of
NO2 and NO3 concentrations in a flow of ambient air. The optimal averaging time is found to be on the order of 400 s and appears to be
limited by the drift of the spectrometer. At this averaging time the smallest detectable absorption is 2×10−10 cm−1, which corresponds to detection limits of 600 pptv for NO2 and 2 pptv for NO3. This compact and low cost instrument is a promising diagnostic tool for air quality control in urban environments. 相似文献
3.
4.
Cavity ringdown (CRD) spectroscopy, with its high sensitivity, provides a novel way to perform continuous-wave (cw) stimulated
Raman gain (SRG) spectroscopy, rather than by conventional optically detected coherent Raman techniques. Tunable cw laser
light at ∼1544 nm is used to probe ringdown decay from a rapidly-swept, high-finesse optical cavity containing a gas-phase
sample of interest and itself located inside the cavity of a cw single-longitudinal-mode Nd:YAG ring laser operating at ∼1064.4
nm. This approach is used to measure cw SRG spectra of the ν
1 fundamental rovibrational Raman band of methane gas at ∼2916.5 cm−1. The resulting SRG-CRD resonances have ringdown times longer than in the off-resonance case, in contrast to the usual shorter
ringdown times arising from absorption and other loss processes. Previously reported noise-equivalent sensitivities have been
substantially improved, by using a second ringdown cavity to facilitate subtraction of infrared-absorption background signals.
Moreover, by employing a ringdown cavity in the form of a ring, the SRG-pump and CRD-detected Stokes beams can co-propagate
uni-directionally, which significantly reduces Doppler broadening. 相似文献
5.
Kasyutich V.L. Bale C.S.E. Canosa-Mas C.E. Pfrang C. Vaughan S. Wayne R.P. 《Applied physics. B, Lasers and optics》2003,76(6):691-697
We present an application of cavity-enhanced absorption spectroscopy with an off-axis alignment of the cavity formed by two
spherical mirrors and with time integration of the cavity-output intensity for detection of nitrogen dioxide (NO2) and iodine monoxide (IO) radicals using a violet laser diode at λ=404.278 nm. A noise-equivalent (1σ≡ root-mean-square variation
of the signal) fractional absorption for one optical pass of 4.5×10-8 was demonstrated with a mirror reflectivity of ∼0.99925, a cavity length of 0.22 m and a lock-in-amplifier time constant
of 3 s. Noise-equivalent detection sensitivities towards nitrogen dioxide of 1.8×1010 molecule cm-3 and towards the IO radical of 3.3×109 molecule cm-3 were achieved in flow tubes with an inner diameter of 4 cm for a lock-in-amplifier time constant of 3 s. Alkyl peroxy radicals
were detected using chemical titration with excess nitric oxide (RO2+NO→RO+NO2). Measurement of oxygen-atom concentrations was accomplished by determining the depletion of NO2 in the reaction NO2+O→NO+O2. Noise-equivalent concentrations of alkyl peroxy radicals and oxygen atoms were 3×1010 molecule cm-3 in the discharge-flow-tube experiments.
Received: 4 February 2003 / Revised version: 10 March 2003 / Published online: 12 May 2003
RID="*"
ID="*"Corresponding author. Fax: +44-1865/275-410, E-mail: vlk@physchem.ox.ac.uk 相似文献
6.
D. J. Hamilton M. G. D. Nix S. G. Baran G. Hancock A. J. Orr-Ewing 《Applied physics. B, Lasers and optics》2010,100(2):233-242
Optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS) has been demonstrated by coupling a distributed feedback
diode laser to a ring cavity. Frequency-selected light decaying from the ring cavity is retro-reflected, inducing a counter-propagating
intra-cavity beam, and providing optical feedback to the laser. At specific laser-to-cavity distances, all cavity mode frequencies
return to the diode laser with the same phase, allowing spectra to be accumulated across the range of frequencies of the current-tuned
laser. OF-CEAS has been used to measure very weak oxygen isotopologue (16O18O and 16O17O) absorptions in ambient air at wavelengths near 762 nm using the electric-dipole forbidden O2
A-band. A bandwidth reduced minimum detectable absorption coefficient of 2.2×10−9 cm−1 Hz−1/2 is demonstrated. 相似文献
7.
A. A. Kosterev P. R. Buerki L. Dong M. Reed T. Day F. K. Tittel 《Applied physics. B, Lasers and optics》2010,100(1):173-180
A quartz enhanced photoacoustic spectroscopy sensor designed for fast response was used in combination with a pulsed external
cavity quantum cascade laser to rapidly acquire gas absorption data over the 1196–1281 cm−1 spectral range. The system was used to measure concentrations of water vapor, pentafluoroethane (freon-125), acetone, and
ethanol both individually and in combined mixtures. The precision achieved for freon-125 concentration in a single 1.1 s long
spectral scan is 13 ppbv. 相似文献
8.
Xiaojuan Cui Christophe Lengignon Weixiong Zhao Gerard Wysocki Eric Fertein Cécile Coeur Andy Cassez Laurence Croize Weidong Chen Yingjian Wang Weijun Zhang Xiaoming Gao Wenqing Liu Yujun Zhang Fengzhong Dong 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(11):1300-1316
Chemically reactive atmospheric species play a crucial role in tropospheric processes which affect regional air quality and global climate change. Contrary to long-lived species such as greenhouse gases, interference-free accurate and precise concentration assessments of strongly reactive short-lived species represent a real challenge. In this paper, we report on the recent progress in spectroscopic instrumental developments for monitoring of OH, NO3, HONO and NO2 by using modern photonic sources (Quantum Cascade Laser, distributed feedback diode laser, light emitting diode) in conjunction with high-sensitivity spectroscopic measurement techniques such as multi-pass cell based long optical path length absorption spectroscopy, wavelength-modulation enhanced off-axis integrated cavity output spectroscopy, Faraday rotation spectroscopy, incoherent broadband cavity enhanced absorption spectroscopy. The main techniques available for routine atmospheric measurements of OH, NO3 and HONO are overviewed, in comparison with the emerging modern photonic spectroscopy techniques. 相似文献
9.
L. Ciaffoni B. L. Cummings W. Denzer R. Peverall S. R. Procter G. A. D. Ritchie 《Applied physics. B, Lasers and optics》2008,92(4):627-633
High resolution diode laser spectroscopy has been applied to the detection of hydrogen sulphide at ppm levels utilizing different
transitions within the region of the ν
1+ν
2+ν
3 and 2ν
1+ν
2 combination bands around 1.58 μm. Suitable lines in this spectral region have been identified, and absolute absorption cross
sections have been determined through single-pass absorption spectroscopy and confirmed in the Doppler linewidth regime using
cavity enhanced absorption spectroscopy (CEAS). The desire for a sensitive system potentially applicable to H2S sensing at atmospheric pressure has led to an investigation on suitable transitions using wavelength modulation spectroscopy
(WMS). The set-up sensitivity has been calculated as 1.73×10−8 cm−1 s1/2, and probing the strongest line at 1576.29 nm a minimum detectable concentration of 700 ppb under atmospheric conditions
has been achieved. Furthermore, pressure broadening coefficients for a variety of buffer gasses have been measured and correlated
to the intermolecular potentials governing the collision process; the H2S–H2S dimer well depth is estimated to be 7.06±0.09 kJ mol−1. 相似文献
10.
Continuous wave,distributed feedback diode laser based sensor for trace-gas detection of ethane 总被引:1,自引:0,他引:1
K. Krzempek R. Lewicki L. Nähle M. Fischer J. Koeth S. Belahsene Y. Rouillard L. Worschech F. K. Tittel 《Applied physics. B, Lasers and optics》2012,106(2):251-255
The development of a continuous wave (CW), thermoelectrically cooled (TEC), distributed feedback (DFB) laser diode based spectroscopic
trace-gas sensor for ultra-sensitive and selective ethane (C2H6) concentration measurements is reported. The sensor platform used tunable diode laser absorption spectroscopy (TDLAS) based
on a 2f wavelength modulation (WM) detection technique. TDLAS was performed with a 100 m optical path length astigmatic Herriott
cell. For an interference free C2H6 absorption line located at 2976.8 cm−1 a 1σ minimum detection limit of 240 pptv (part per trillion by volume) with a 1 second lock-in amplifier time constant was achieved.
In addition, reliable and long-term sensor performance was obtained when operating the sensor in an absorption line locked
mode. 相似文献
11.
NO trace gas sensor based on quartz-enhanced photoacoustic spectroscopy and external cavity quantum cascade laser 总被引:1,自引:0,他引:1
V. Spagnolo A. A. Kosterev L. Dong R. Lewicki F. K. Tittel 《Applied physics. B, Lasers and optics》2010,100(1):125-130
A gas sensor based on quartz-enhanced photoacoustic detection and an external cavity quantum cascade laser was realized and
characterized for trace nitric oxide monitoring using the NO R(6.5) absorption doublet at 1900.075 cm−1. Signal and noise dependence on gas pressure were studied to optimize sensor performance. The NO concentration resulting
in a noise-equivalent signal was found to be 15 parts per billion by volume, with 100 mW optical excitation power and a data
acquisition time of 5 s. 相似文献
12.
The cavity ring down (CRD) technique presented here involves an optical cavity attached to a cryostat. The static cell and
mirrors of the optical cavity are all inside a vacuum chamber at the same temperature of the cryostat. The temperature of
the cell can be changed between 77 K and 298 K. An off-axis alignment of the laser beam into the cavity is used to increase
the number of resonant modes inside the cavity and improve the signal to noise ratio of the absorption bands. To demonstrate
the capabilities of the low temperature CRD cell, the absorption spectra of O2 are recorded at 90 K for the A (υ′=0←υ″=0) and γ (υ′=2←υ″=0) bands of the b1?g +? X3?g -b^{1}\sum_{g}^{ +}\leftarrow X^{3}\sum_{g}^{ -} transition using cavity ring down spectroscopy. The optical cavity performance was tested using two variations of the CRD
technique. The A-band is measured using the phase-shift cavity ring down method and the γ-band using the pulsed-laser exponential-decay method. A comparison between experimental and simulated spectra of the O2 bands at 90 K confirms the molecular temperature measured by a sensor localized in the cell. Quantitative measurements of
the individual rotational line intensities are made for the oxygen γ-band to confirm the temperature of the cell and calculate the vibrational band intensity. The application of this technique
for laboratory studies of planetary atmospheres and the spectroscopy of molecular complexes is emphasized. 相似文献
13.
T. Wu W. Chen E. Fertein F. Cazier D. Dewaele X. Gao 《Applied physics. B, Lasers and optics》2012,106(2):501-509
We report on the development of an optical instrument based on incoherent broadband cavity-enhanced absorption spectroscopy
(IBBCEAS) for simultaneous open-path measurements of nitrous acid (HONO) and nitrogen dioxide (NO2) in ambient air using a UV light emitting diode operating at ∼366 nm. Detection limits of ∼430 pptv for HONO and ∼1 ppbv
for NO2 were achieved with an optimum acquisition time of 90 s, determined by an Allan variance analysis. Based on a 1.85 m long
high optical finesse open-path cavity, the effective optical path length of 2.8 km was realized in aerosol-free samples or
in an urban environment at modest aerosol levels. Such a kilometer long optical absorption is comparable to that achieved
in the well established differential optical absorption spectroscopy (DOAS) technology while keeping the instrument very compact.
Open-path detection configuration allows one to avoid absorption cell wall losses and sampling induced artifacts. The demonstrated
sensitivity and specificity shows high potential of this cost-effective and compact infrastructure for future field applications
with high spatial resolution. 相似文献
14.
15.
M. L. Hamilton R. Peverall G. A. D. Ritchie L. J. Thornton J. H. van Helden 《Applied physics. B, Lasers and optics》2009,97(3):715-722
We have demonstrated the production of ∼1.9 μm near-infrared radiation by using difference frequency generation within a 5%
MgO doped PPLN crystal by coupling ∼735 nm radiation from a tunable external cavity diode laser with relatively high powered
532 nm radiation from both Nd:YVO3 and Nd:YAG lasers. The radiation produced is of low power, ∼15 μW, and was used in conjunction with the sensitivity enhancing
techniques of wavelength modulation spectroscopy (WMS) and cavity enhanced absorption spectroscopy (CEAS). Experiments were
carried out on rotationally resolved transitions in the combination bands of NH3 and CO2 in the 1.9 μm region. An α
min value of 3.6×10−6 cm−1 Hz−1/2 was achieved for WMS measurements on CO2. A comparable α
min value of 2.2×10−6 cm−1 Hz−1/2 was achieved for NH3 using CEAS. The low NIR power indicates that despite the level of MgO doping quoted for the crystal, under prolonged exposure
photorefractive damage has occurred. 相似文献
16.
Laser irradiation of tungsten and gold nanoparticles in aqueous solutions of Th(NO3)4 was experimentally studied. Picosecond Nd:YAG lasers with a wavelength of 1.06 μm and a peak power from 1011 to 1013 W cm−2 were used. The composition of colloidal solutions before and after laser irradiation was analyzed using atomic absorption
and gamma spectrometry. It was found that laser irradiation initiates nuclear reactions involving thorium nuclei, occurring
via two different channels. Radioactive decay of thorium nuclei within its radioactive series is enhanced under laser irradiation
in D2O; one of the fission fragments is 137Cs. Possible mechanisms of the process are discussed. 相似文献
17.
W. Zhao X. Gao W. Chen W. Zhang T. Huang T. Wu H. Cha 《Applied physics. B, Lasers and optics》2007,86(2):353-359
A novel instrument based on an improved off-axis alignment of integrated cavity output spectroscopy (OA-ICOS) in conjunction
with a wavelength modulation (WM) technique, was developed using a DFB diode laser operating in the near infrared at 1.573 μm
(6357.3 cm-1). The laser-based sensor employed a 44 cm optical cavity that provided an effective absorption path length of ∼68 m. A minimum
detectable absorption of approximately 3.6 ppmv Hz-1/2 or 2.3×10-7 Hz-1/2 per optical pass was obtained using second harmonic detection. We demonstrated that by implementation of the WM technique
to OA-ICOS in the near infrared, the detection sensitivity was improved by a factor of 14 compared to that obtained with OA-ICOS.
Measurements of CO2 mixing ratios in ambient air have been performed by using both OA-ICOS and WM-OA-ICOS techniques for performance comparison.
PACS 42.62.Fi; 07.07.Df; 33.20.Ea 相似文献
18.
Nickel oxide and chromium-doped nickel oxide (Ni0.95Cr0.03O1−δ
) were prepared by thermal decomposition of nitrates. The obtained NiO and Ni0.95Cr0.03O1−δ
samples were utilized as sensing electrodes (SEs) in yttria-stabilized zirconia (YSZ)-based sensors for detection of NO2 at 800 °C under wet condition (5 vol.% H2O). While the mixed-potential-type planar sensor attached with NiO-SE gave rather large NO2 sensitivity, the sensor attached with Ni0.95Cr0.03O1−δ
-SE exhibited fast recovery rate with an acceptable sensitivity. The Δemf (electromotive force) of the sensors varied linearly
with NO2 concentration in the examined range of 50–400 ppm on a logarithmic scale. Based on the results of measurements for polarization,
complex impedance and gas phase catalysis, the fast recovery was attributable to the high rate for the anodic reaction of
O2 at the Ni0.95Cr0.03O1−δ
/YSZ interface, and the lower NO2 sensitivity was caused by both the high rate for the anodic reaction of O2 and the high degree for the gas phase conversion of NO2 to NO. 相似文献
19.
A sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS) was evaluated for the detection of trace levels of ethylene
at atmospheric pressure using a fiber coupled DFB diode laser emitting in the 1.62 μm spectral range. A noise-equivalent QEPAS signal of ∼4 ppm C2H4 was achieved for a 0.7 s data acquisition time using wavelength-modulation with a second-harmonic detection scheme on the
strongest C2H4 absorption peak at 6177.14 cm−1 with an average optical power of ∼15 mW. Improved detection sensitivity of 0.5 and 0.3 ppm C2H4 (1σ) was demonstrated using longer averaging time of 70 and 700 s, respectively. Important characteristics for the QEPAS based
sensor operation in real-world conditions are presented, particularly the influence of external temperature variations. Furthermore,
the response time of the ethylene sensor was measured in different configurations and it is shown that the QEPAS technique
can provide a response time in a few seconds range even without active gas flow. 相似文献
20.
I. Courtillot J. Morville V. Motto-Ros D. Romanini 《Applied physics. B, Lasers and optics》2006,85(2-3):407-412
We report preliminary results on the first application of optical feedback cavity-enhanced absorption spectroscopy with a blue (411 nm) extended cavity diode laser (ECDL) for NO2 detection. While this technique was originally developed to operate with distributed feedback diode lasers in the near infrared, it is here extended to ECDLs and applied to the blue spectral region. With a simple and compact optical setup, we demonstrate from the baseline noise a minimum detectable NO2 concentration of 6×109 molecules/cm3 for a single laser scan (70 ms), which extrapolated under atmospheric conditions corresponds to 200 pptv. Signal averaging should allow further lowering of this limit. Observed absorption spectra display more structure than previous spectra obtained at lower resolution by Fourier-transform spectroscopy at the same wavelength. PACS 07.88.+y; 42.55.Px; 42.62.Fi 相似文献