共查询到20条相似文献,搜索用时 437 毫秒
1.
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
2.
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
3.
M. Fukuda S. Ooyama A. Utsumi Y. Kondo T. Kurosaki T. Masuda 《Applied physics. B, Lasers and optics》2008,90(2):269-272
The effect of optical feedback noise of a laser diode on the stability of gas-absorption spectra was investigated by monitoring
the optical absorption of CO2 gas. Lasing longitudinal mode instability greatly degraded the shape of the absorption spectra, and coherence collapse in
the laser diode greatly broadened the spectra. The correlation between the optical feedback noise of the laser diode and the
shape of the gas-absorption spectra was clarified on the basis of these spectral behaviors.
PACS 42.62.Fi; 42.55.Px; 42.68.Ca 相似文献
4.
A combination of optical feedback self-locking of a continuous-wave distributed feedback diode laser to a V-shaped high finesse cavity, laser phase modulation at a frequency equal to the free spectral range of the V-cavity and detection of the transmitted laser beam at this high modulation frequency is described for the possible application in cavity-enhanced absorption spectroscopy. In order to estimate the noise level of an absorbance baseline, the triplet of frequency modulated light, i.e. the central laser frequency and the two sidebands, were transmitted through both the V-cavity in open air and a 1.5-cm long optical cell placed behind the cavity output mirror and filled with acetylene (C2H2) at low pressure. The performance of the setup was evaluated from the measured relative intensity noise on the cavity output (normalised by the bandwidth) and the frequency modulation absorption signals induced by C2H2 absorption in the 1.5-cm cell. From these data, we estimate that the noise-equivalent absorption sensitivity of 2.1 × 10?11 cm?1 Hz?1/2—by a factor of 11.7 above the shot-noise limit—can be achieved for C2H2 absorption spectra extracted from the heterodyne beat signals recorded at the transmission maxima intensity peaks of the successive TEM00 resonances. 相似文献
5.
The paper presents a signal processing system used for nitrogen dioxide detection employing cavity enhanced absorption spectroscopy.
In this system, the absorbing gas concentration is determined by the measurement of a decay time of a light pulse trapped
in a cavity.
The setup includes a resonance optical cavity, which was equipped with spherical and high reflectance mirrors, the pulsed
diode laser (414 nm) and electronic signal processing system. In order to ensure registration of low-level signals and accurate
decay time measurements, special preamplifier and digital signal processing circuit were developed.
Theoretical analyses of main parameters of optical cavity and signal processing system were presented and especially signal-to-noise
ratio was taken into consideration. Furthermore, investigation of S/N signal processing system and influence of preamplifier
feedback resistance on the useful signal distortion were described.
The aim of the experiment was to study potential application of cavity enhanced absorption spectroscopy for construction of
fully optoelectronic NO2 sensor which could replace, e.g., commonly used chemical detectors. Thanks to the developed signal processing system, detection
limit of NO2 sensor reaches the value of 0.2 ppb (absorption coefficient equivalent = 2.8 × 10−9 cm−1). 相似文献
6.
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
7.
V. M. Baev J. Eschner E. Paeth R. Schüler P. E. Toschek 《Applied physics. B, Lasers and optics》1992,55(6):463-477
A multi-mode diode laser with an external cavity is studied experimentally and theoretically for its application to intra-cavity spectroscopy. One facet of a typical Ga0.89Al0.11As laser diode was antireflection-coated by deposition of HfO2 such that 10–3 residual reflectivity was left over. This diode was placed in an external optical cavity. The emission spectrum of this diode laser is highly sensitive to any frequency-dependent loss in the cavity, and the detectivity of such a loss grows with the pump rate. Even close to threshold, the absorption at 780 nm of Rb atoms with a density of 5×1010 cm–3 has been detected. An adequate model for diode lasers based on rate equations and including frequency-dependent gain saturation is developed and applied to the calculations of output spectra. The sensitivity of these spectra to intra-cavity absorption is determined by the overall cavity loss — which is rather high — and the fraction of spontaneous emission in the total emission, in contrast with dye lasers where it is limited by nonlinear mode coupling. Various criteria for the sensitivity are suggested. The smallest detectable absorption with a perfectly antireflection-coated laser is 10–6 cm–1. Improvement of the characteristics of the laser diode would increase the sensitivity. 相似文献
8.
Karol Krzempek Mohammad Jahjah Rafał Lewicki Przemysław Stefański Stephen So David Thomazy Frank K. Tittel 《Applied physics. B, Lasers and optics》2013,112(4):461-465
The development of a continuous wave, thermoelectrically cooled (TEC), distributed feedback diode laser-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) and wavelength modulation spectroscopy as the detection technique. TDLAS was performed using an ultra-compact 57.6 m effective optical path length innovative spherical multipass cell capable of 459 passes between two mirrors separated by 12.5 cm and optimized for the 2.5–4 μm range TEC mercury–cadmium–telluride detector. For an interference-free C2H6 absorption line located at 2,976.8 cm?1, a 1σ minimum detection limit of 740 pptv with a 1 s lock-in amplifier time constant was achieved. 相似文献
9.
A detection limit of 200 ppt of NO2 in N2 at atmospheric pressure was obtained with a photoacoustic detector and a high power blue laser diode. This corresponds to
a normalized noise (1σ) equivalent absorption coefficient of 2×10-9 cm-1W/Hz0.5. Measurements at different laser modulation frequencies showed no frequency dependence of the photoacoustic signal, indicating
a relaxation time τ < 4 μs. Mixing O2 into the NO2 containing gas results in a decrease of the photoacoustic signal. A simple model shows that this effect can be attributed
to an increased vibrational-vibrational relaxation of NO2 to O2.
PACS 31.70.Hq; 34.50.Ez; 42.55.Px 相似文献
10.
制备了高折射率Tm3+/Yb3+共掺杂铋碲酸盐玻璃,利用棱镜耦合法测量出玻璃在632.8和1550nm波长处的折射率分别为2.0365和1.9795. 对玻璃的吸收、荧光和红外透过光谱展开了测试与分析,根据Judd-Ofelt理论对吸收光谱进行拟合,求得Tm3+的振子强度参数Ωt(t=2,4,6)分别为3.90×10-20, 2.03×10-20和9.03×10-2
关键词:
3+/Yb3+共掺')" href="#">Tm3+/Yb3+共掺
铋碲酸盐玻璃
光谱参数
上转换荧光 相似文献
11.
The measurement of relative intensities in CO2 combination bands spectrum is performed using wavelength modulation spectroscopy (WMS) and a DFB (distributed feedback) diode
laser operating at 1.6 μm. The diode laser is stabilized with an external Fabry–Pérot interferometer and absorption spectroscopy
is performed in a multipass gas cell. A spectrum containing spectral lines of both 13CO2 and 12CO2 isotopic species is recorded. The variation of laser power during frequency scanning and the line shape are taken into account
to accurately extract line intensities from experimental data. The isotopic concentration ratio is deduced from the intensity
ratio. Both ratios are measured with an accuracy of about 0.5% in pure CO2.
Received: 9 June 2000 / Published online: 8 November 2000 相似文献
12.
S. Uetake A. Yamaguchi D. Hashimoto Y. Takahashi 《Applied physics. B, Lasers and optics》2008,93(2-3):409-414
We have successfully observed high-resolution spectra of spin-forbidden electric quadrupole transition (1 S 0→3 D 2) in ytterbium (174Yb) atoms. The differential light shifts between the 1 S 0 and the 3 D 2 states in a far-off resonant trap at 532 nm are also measured. For the spectroscopy, we developed simple, narrow-linewidth, and long-term frequency stabilized violet diode laser systems. Long-term drifts of the excitation laser (404 nm) is suppressed by locking the laser to a length stabilized optical cavity. The optical path length of the cavity is stabilized to another diode laser whose frequency is locked to a strong 1 S 0→1 P 1 transition (399 nm) of Yb. Both lasers are standard extended-cavity diode lasers (ECDLs) in the Littrow configuration. Since the linewidth of a violet ECDL (~10 MHz) is broader than a typical value of a red or near infra-red ECDL (<1 MHz), we employ optical feedback from a narrow-band Fabry–Perot cavity to reduce the linewidth. The linewidth is expected to be <20 kHz for 1 ms averaging time, and the long-term frequency stability is estimated to be ~200 kHz/h. 相似文献
13.
We fabricate a low noise erbium-doped fiber ring laser that can be continuously tuned over 102 nm by insertion of the fiber Fabry-Perot tunable filter (FFP-TF) in the ring cavity with a novel cavity structure and the optimal gain medium length. As an application of this fiber ring laser, we performed the absorption spectroscopy of acetylene (13C2H2) and hydrogen cyanide (H13C14N) and measure the absorption spectra of more than 50 transition lines of these gases with an excellent signal to noise ratio (SNR). The pressure broadening coefficients of four acetylene transition lines are obtained using this fiber ring laser and an external cavity laser diode. 相似文献
14.
Many Pand R-branch lines of the fundamental bands of the 12C14N and 13C14N radicals in their ground (2Σ+) electronic state have been measured at high resolution by diode laser absorption spectroscopy. The radicals were generated in a 2.45 GHz planar microwave plasma in 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 2000.084 70(30) cm?1. The main product detected in the plasma by diode laser spectroscopy is HCN, with concentrations about three orders of magnitude higher than CN. 相似文献
15.
Gain versus tuning issues to Q-switch with Yb<Superscript>3+</Superscript>:LSO and amplify broad-bandwidth pulses 总被引:1,自引:0,他引:1
We report on the development of Incoherent Broadband Cavity Enhanced Absorption Spectroscopy (IBBCEAS) using a blue light
emitting diode (LED) for the detection of NO2 in laboratory ambient air. Absorption of the oxygen collisional pair in the atmosphere was also detected in the same spectral
range. The mirror reflectivity was determined using a standard gas sample mixture of NO2, and calibrated with the help of the absorption spectrum of the oxygen collisional pair in pure oxygen at atmospheric pressure.
Optimization of the experimental parameters was investigated and is discussed in detail. For the first time in IBBCEAS involving
broadband absorption spectra, averaging time for signal-to-noise ratio enhancement has been optimized using Allan variance
plot. 18.1 ppbv NO2 in laboratory ambient air has been retrieved from the absorption spectra using differential fitting method over a 40 nm spectral
region centered at 470 nm. A minimum detection sensitivity of about 2.2 ppbv (1σ) for NO2 at atmospheric pressure has been achieved using the optimal averaging time of 100 s by means of a high finesse optical cavity
formed with two moderate reflectivity (∼99.55%) mirrors. No purging of the cavity mirrors by high purity He or N2 gas streams was necessary to prevent contamination of the mirror faces for the in situ measurements. 相似文献
16.
M. A. Bolshov Y. A. Kuritsyn V. V. Liger V. R. Mironenko S. B. Leonov D. A. Yarantsev 《Applied physics. B, Lasers and optics》2010,100(2):397-407
A tunable diode laser absorption spectroscopy (TDLAS) technique and appropriate instrumentation was developed for the measurement
of temperature and water vapor concentrations in heated gases. The technique is based on the detection of the spectra of H2O absorption lines with different energies of low levels. The following absorption lines of H2O were used: 7189.344 cm−1 (E″=142 cm−1), 7189.541 cm−1 (E″=1255 cm−1), 7189.715 cm−1 (E″=2005 cm−1). Spectra were recorded using fast frequency scanning of a single distributed feedback (DFB) laser. A unique differential
scheme for the recording of the absorption spectra was developed. An optimal technique for fitting the experimental spectra
was developed. 相似文献
17.
D. A. Brazhnikov I. V. Nikolaev V. N. Ochkin M. V. Spiridonov S. N. Tskhai 《Laser Physics》2009,19(6):1323-1329
The trace atmospheric concentrations of NO2 are measured with the methods of the diode laser absorption spectroscopy and the phase shift of the modulated radiation. An electronic transition in a range of 415 nm is employed. For a measurement time of 20 ms, the sensitivity of the concentration measurements is about 10?11 relative to the concentration of air particles (0.02 ppbv). At a time interval of 5–10 min, the reproducibility of the absolute concentration measurements (0.1 ppbv) is limited by the low-frequency fluctuations of the optical parameters of the spectrometer and the calibration system and corresponds to the level determined by the Allan variance. 相似文献
18.
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
19.
L. Gianfrani G. Gagliardi G. Pesce A. Sasso 《Applied physics. B, Lasers and optics》1997,64(4):487-491
An AlGaAs diode laser was used to detect NO2 absorption lines belonging to the (0 0 0)–(2 13 1) vibrational band, within the X˜2
A
1 electronic ground state, at 739 nm. A simple absorption spectrometer based on wavelength-modulation spectroscopy with second-harmonic
detection was developed. The minimum detectable pressure of pure NO2 was 0.1 μbar with 2 m absorption path-length, corresponding to an absorbance of 10-6. High-sensitivity detection of NO2 was also performed in the presence of N2 and air at different total pressures: The effects on the detection limit of our apparatus were accurately investigated. The
minimum NO2 concentration at 500 mbar of air was measured to be 2 ppm.
Received: 11 June 1996 / Revised version: 11 October 1996 相似文献
20.
Recep B?y?k 《Physica B: Condensed Matter》2009,404(20):3483-3486
VO2+ doped l-alanine (C3H7NO2) single crystals and powders are examined by electron paramagnetic resonance (EPR) and optical absorption spectroscopy. Three magnetically different sites are resolved from angular variations of l-alanine single crystal EPR spectra. In some specific orientations each VO2+ line splits into three superhyperfine lines with intensities of 1:2:1 and maximum splitting value of 2.23 mT. The local symmetries of VO2+ complex sites are nearly axial. The optical absorption spectra show three bands. Spin Hamiltonian parameters are measured and molecular orbital coefficients are calculated by correlating EPR and optical absorption data for the central vanadyl ion. 相似文献