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1.
V.L. Kasyutich R.J. Holdsworth P.A. Martin 《Applied physics. B, Lasers and optics》2008,92(2):271-279
We describe the performance of two mid-infrared laser spectrometers for carbon monoxide, nitrous oxide and nitric oxide detection.
The first spectrometer for CO and N2O detection around 2203 cm-1 is based upon all-diode laser difference frequency generation (DFG) in a quasi-phase matched periodically-poled lithium niobate
(PPLN) crystal using two continuous-wave room-temperature distributed feedback diode lasers at 859 and 1059 nm. We also report
on the performance of a mid-infrared spectrometer for NO detection at ∼ 1900 cm-1 based upon a thermoelectrically-cooled continuous-wave distributed feedback quantum cascade laser (QCL). Both spectrometers
had a single-pass optical cell and a thermoelectrically cooled HgCdZnTe photovoltaic detector. Typical minimum detection limits
of 2.8 ppmv for CO, 0.6 ppmv for N2O and 2.7 ppmv for NO have been demonstrated for a 100 averaged spectra acquired within 1.25 s and a cell base length of 21 cm
at ∼ 100 Torr. Noise-equivalent absorptions of 10-5 and 10-4 Hz-1/2 are typically demonstrated for the QCL and the DFG based spectrometers, respectively.
PACS 42.55.Px; 42.62.Fi; 42.65.-k; 42.72.Ai; 42.68.Ca 相似文献
2.
Z. W. Liu X. F. Yang A. M. Zhu G. L. Zhao Y. Xu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(3):365-373
The hydroxyl radical (OH) plays an important role in combustion systems,
atmospheric chemistry and the removal of air pollutants by non-thermal
plasmas. The present work reports the determination of the hydroxyl radicals
in atmospheric dielectric barrier discharge plasmas via near infrared
continuous wave cavity ring-down spectroscopy. The P-branches of OH
X2Πi (ν' = 2 ←ν′′ = 0) bands were used for its number density measurements. The minimum measurable absorption coefficient is about
3 × 10-8 cm-1 in DBD plasmas. At certain experimental
conditions (a.c. frequency of 70 kHz, 6700 ppm H2O in He, 1 atm), when
the peak-to-peak discharge voltage varied from 6 kV to 10.4 kV, the
determined OH radical concentration increased from (2.1 ± 0.1) ×
1013 molecules cm-3 to (3.7 ± 0.1) × 1013 molecules cm-3. The plasma gas temperature, derived from the Boltzmann plots of OH rotational population distributions, ranged from 312
± 10 K to 363 ± 10 K when the discharge voltage was raised in the above range.
The influences of O2 and N2 addition on the production of OH
radicals have been also investigated. 相似文献
3.
J. J. Camacho M. Santos L. Díaz L. J. Juan J. M. L. Poyato 《Applied Physics A: Materials Science & Processing》2010,99(1):159-175
A spectroscopic study of ambient air plasma, initially at room temperature and pressures ranging from 32 to 101 kPa, produced
by high-power transverse excitation atmospheric (TEA) CO2 laser (λ=9.621 and 10.591 μm; τ
FWHM≈64 ns; power densities ranging from 0.29 to 6.31 GW cm−2) has been carried out in an attempt to clarify the processes involved in laser-induced breakdown (LIB) air plasma. The strong
emission observed in the plasma region is mainly due to electronic relaxation of excited N, O and ionic fragments N+. The medium-weak emission is due to excited species O+, N2+, O2+, C, C+, C2+, H, Ar and molecular band systems of N
2+(_{2}^{+}(
B
2\varSigma u+^{2}\varSigma _{\mathrm{u}}^{+}
–X
2\varSigma g+)^{2}\varSigma _{\mathrm{g}}^{+})
, N2(C3
Π
u–B3
Π
g), N
2+(_{2}^{+}(
D2
Π
g–A2
Π
u) and OH(A2
Σ
+–X2
Π). Excitation temperatures of 23400±700 K and 26600±1400 K were estimated by means of N+ and O+ ionic lines, respectively. Electron number densities of the order of (0.5–2.4)×1017 cm−3 and (0.6–7.5)×1017 cm−3 were deduced from the Stark broadening of several ionic N+ and O+ lines, respectively. Estimates of vibrational and rotational temperatures of N
2+_{2}^{+}
electronically excited species are reported. The characteristics of the spectral emission intensities from different species
have been investigated as functions of the air pressure and laser irradiance. Optical breakdown threshold intensities in air
at 10.591 μm have been measured. 相似文献
4.
《Proceedings of the Combustion Institute》2023,39(2):1625-1633
In order to achieve carbon neutrality, the use of ammonia as a fuel for power generation is highly anticipated. The utilization of a binary fuel consisting of ammonia and hydrogen can address the weak flame characteristics of ammonia. In this study, the product gas characteristics of ammonia/hydrogen/air premixed laminar flames stabilized in a stagnation flow were experimentally and numerically investigated for various equivalence ratios for the first time. A trade-off relationship between NO and unburnt ammonia was observed at slightly rich conditions. At lean conditions, NO reached a maximum value of 8,700 ppm, which was larger than that of pure ammonia/air flames. The mole fraction of nitrous oxide (N2O) which has large global warming potential rapidly increased around the equivalence ratio of 0.6, which was attributed to the effect of a decrease in flame temperature downstream of the reaction zone owing to heat loss to the stagnation wall. To understand this effect further, numerical simulations of ammonia/hydrogen/air flames were conducted using the stagnation flame model for various equivalence ratios and stagnation wall temperatures. The results show that the important reactions for N2O production and reductions are NH +NO = N2O + H, N2O + H = N2 + OH, and N2O (+M) = N2 + O (+M). A decrease in flame temperature in the post flame region inhibited N2O reduction through N2O (+M) = N2 + O (+M) because this reaction has a large temperature dependence, and thus N2O was detected as a product gas. N2O is reduced through N2O (+M) = N2 + O (+M) in the post flame region if the stagnation wall temperature is sufficiently high. On the other hand, it was clarified that an increase in equivalence ratio enhances H radical production and promotes N2O reduction by H radical through the reaction of N2O + H = N2 + OH. 相似文献
5.
Shaolin Liao Ronald J. Vernon 《International Journal of Infrared and Millimeter Waves》2007,28(6):479-490
The newly developed Taylor-Interpolation-FFT (TI-FFT) algorithm dramatically increases the computational speeds for millimeter
wave propagation from a planar (cylindrical) surface onto a “quasi-planar” (“quasi-cylindrical”) surface. Two different scenarios
are considered in this article: the planar TI-FFT is for the computation of the wave propagation from a plane onto a “quasi-planar” surface and the cylindrical TI-FFT is for the computation of wave propagation from a cylindrical surface onto a “quasi-cylindrical” surface. Due to the
use of the FFT, the TI-FFT algorithm has a computational complexity of O(N
2 log2
N
2) for an N × N computational grid, instead of N
4 for the direct integration method. The TI-FFT algorithm has a low sampling rate according to the Nyquist sampling theorem.
The algorithm has accuracy down to −80 dB and it works particularly well for narrow-band fields and “quasi-planar” (“quasi-cylindrical”)
surfaces. 相似文献
6.
A. K. Shuaibov 《Journal of Applied Spectroscopy》1999,66(2):256-262
Survey emission spectra in the region of 190–600 nm and time and service-life characteristics of a transverse nanosecond discharge
in He/Ar/CF2Cl2(CCl4) mixtures at a pressure of 10–100 kPa are investigated. In the emission spectra, excited products of the decomposition of
freons—C2(A−X), CN(B−X), Cl
2
*
, C*, Cl*, and Cl+*— and the emission of ArF at λ=193 nm are revealed. The emissions of Cl
2
*
at λ=258 nm and ArF at λ=193 nm were the most intense. The discharge in the He/Ar/CF2Cl2 mixture is a multiwave emission source with λ=258 nm Cl
2
*
193 nm ArF, and probably, 175 nm Arcl. It is of interest for applications in UV-VUV-range pulse photometry. The duration
of the emission on Cl
2
*
, ArF, ArI, ClI, and ClII transitions in the discharge in the Ar/CF2Cl2 mixture (P=10–20 kPa) was 200–300 nsec. With adding He and increasing pressure to 100 kPa the duration of the emission decreased
by a factor of 1.5–2. The basic mechanisms of the formation of Cl2, ArF, and CN(B) molecules in the transverse-discharge plasma are considered.
Uzhgorod State University, 46, Pidgirna Str., Uzhgorod, 294000, Ukraine. Translated from Zhurnal. Prikladnoi Spektroskopii,
Vol. 66, No. 2, pp. 241–246, March–April, 1999. 相似文献
7.
Hydroxyl tagging velocimetry (HTV) in experimental air flows 总被引:1,自引:0,他引:1
L.A. Ribarov J.A. Wehrmeyer R.W. Pitz R.A. Yetter 《Applied physics. B, Lasers and optics》2002,74(2):175-183
The new nonintrusive instantaneous molecular flow tagging method, hydroxyl tagging velocimetry (HTV), previously demonstrated
only for high-temperature reacting flows, is now demonstrated in low-temperature (300 K) ambient air flowfields. Single-photon
photodissociation of ground-state H2O by a ∼193-nm ArF excimer laser ‘writes’ very long grid lines (>50 mm) of superequilibrium OH and H photoproducts in a room
air flowfield due to the presence of ambient H2O vapor. After displacement, the positions of the OH tag lines are revealed through fluorescence caused by A2Σ+ (ν′=0)?X2Πi (ν′′=0) OH excitation using a pulsed frequency-doubled dye laser with an operating output wavelength of ∼308 nm. The dye ‘read’
laser accesses the strong Q1(1) line, compensating for the relatively weak 193-nm absorption of room-temperature H2O. The weak absorption of ground vibrational state H2O has previously precluded the use of HTV at low temperatures, since previous HTV systems relied on a KrF excimer ‘read’ laser
that could only access a weak (3?0) OH transition. The instantaneous velocity field is determined by time-of-flight analysis.
HTV tag lifetime comparisons between experimental results and theoretical predictions are discussed. Multiple-line tag grids
are shown displaced due to an experimental air flowfield, thus providing 2-D multipoint velocity information. Due to the instantaneous
nature of the HTV tag formation, HTV is particularly suitable for, but not limited to, a variety of fast flowfield applications
including nonreacting base flows for high-speed projectiles and low-temperature hypersonic external or internal flows.
Received: 3 July 2001 / Revised version: 6 November 2001 / Published online: 17 January 2002 相似文献
8.
H. Kim A. Cepler C. Cetina D. Knies M. S. Osofsky R. C. Y. Auyeung A. Piqué 《Applied Physics A: Materials Science & Processing》2008,93(3):593-598
Present p-type ZnO films tend to exhibit high resistivity and low carrier concentration, and they revert to their natural n-type state
within days after deposition. One approach to grow higher quality p-type ZnO is by codoping the ZnO during growth. This article describes recent results from the growth and characterization
of Zr–N codoped p-type ZnO thin films by pulsed laser deposition (PLD) on (0001) sapphire substrates. For this work, both N-doped and Zr–N
codoped p-type ZnO films were grown for comparison purposes at substrate temperatures ranging between 400 to 700 °C and N2O background pressures between 10−5 to 10−2 Torr. The carrier type and conduction were found to be very sensitive to substrate temperature and N2O deposition pressure. P-type conduction was observed for films grown at pressures between 10−3 to 10−2 Torr. The Zr–N codoped ZnO films grown at 550 °C in 1×10−3 Torr of N2O show p-type conduction behavior with a very low resistivity of 0.89 Ω-cm, a carrier concentration of 5.0×1018 cm−3, and a Hall mobility of 1.4 cm2 V−1 s−1. The structure, morphology and optical properties were also evaluated for both N-doped and Zr–N codoped ZnO films. 相似文献
9.
Jesús?álvarez-Ruiz Marien?López-Arias Rebeca?de?Nalda Margarita?Martín Andrés?Arregui Luis?Ba?ares 《Applied Physics A: Materials Science & Processing》2009,95(3):681-687
The formation of cationic clusters in the laser ablation of CdS targets has been investigated as a function of wavelength
and fluence by mass spectrometric analysis of the plume. Ablation was carried out at the laser wavelengths of 1064, 532, 355,
and 266 nm in order to scan the interaction regimes below and above the energy band gap of the material. In all cases, the
mass spectra showed stoichiometric Cd
n
S
n
+ and nonstoichiometric Cd
n
S
n−1+, Cd
n
S
n+1+, and Cd
n
S
n+2+ clusters up to 4900 amu. Cluster size distributions were well represented by a log-normal function, although larger relative
abundance for clusters with n=13, 16, 19, 34 was observed (magic numbers). The laser threshold fluence for cluster observation was strongly dependent on
wavelength, ranging from around 16 mJ/cm2 at 266 nm to more than 300 mJ/cm2 at 532 and 1064 nm. According to the behavior of the detected species as a function of fluence, two distinct families were
identified: the “light” family containing S2+ and Cd+ and the “heavy” clusterized family grouping Cd2+ and Cd
n
S
m
+. In terms of fluence, it has been determined that the best ratio for clusterization is achieved close to the threshold of
appearance of clusters at all wavelengths. At 1064, 532, and 355 nm, the production of “heavy” cations as a function of fluence
showed a maximum, indicating the participation of competitive effects, whereas saturation is observed at 266 nm. In terms
of relative production, the contribution of the “heavy” family to the total cation signal was significantly lower for 266 nm
than for the longer wavelengths. Irradiation at 355 nm in the fluence region of 200 mJ/cm2 has been identified as the optimum for the generation of large clusters in CdS. 相似文献
10.
N. R. Troitsky L. E. Pirogov I. I. Zinchenko J. Yang 《Radiophysics and Quantum Electronics》2005,48(7):491-499
We present results of observations of 23 compact cores of molecular clouds associated with IRAS “ cold” infrared sources.
The observations were performed in the J = 1−0 line of the C18O molecule on a 13.7-meter radio telescope of the Purple Mountain Observatory, China. The C18O (J = 1−0) line was detected in the emission of 21 objects. Column densities of the C18O and H2 molecules towards the maximum of integral intensity of the C18O emission were estimated in the approximation of local thermodynamic equilibrium and amounted to (2.5–10.4) · 1015cm−2 and (1.5–6.1) · 1022 cm−2, respectively. The kinetic temperatures determined for these maxima from the CO lines vary from 14 to 45 K. For six objects,
whose mapping has been almost completed, the dimensions of the C18O emission regions are estimated to range from 0.5 to 1.2 pc. The masses of these objects lie in the range of (390–1750) M⊙ and are close to the estimates following from the virial theorem. The range of average densities of the objects is (0.3–1.4)
· 104 cm−3.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 7, pp. 553–562, July 2005. 相似文献
11.
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
12.
M. Maaza B. D. Ngom S. Khamlich J. B. Kana Kana P. Sibuyi D. Hamidi S. Ekambaram 《Journal of nanoparticle research》2012,14(2):714
The possibility of synthesizing binary oxides nanoparticles in a nano-scaled form by laser liquid solid interaction using
a NdYAG “1.064 μm” as an irradiating laser source is reported. The case of MoO3−δ is emphasized. Furthermore, it is demonstrated that the Mo–O electronic valence can be controlled through the coupling effects
of oxygen enriched nature of the used coating liquid layer, namely pure H2O or H2O2 and the laser beam fluence. Dark blue hydrated molybdic pentoxide Mo2O5·xH2O and yellow molybdenum trioxide MoO3 nano-suspensions were reproducibly synthesized with hydrogen peroxide and water, respectively, at a relatively high ablation
rate. The average size of the molybdenum trioxide nanoparticles was about <ϕ>~8 nm, slightly larger than the molybdic pentoxide
ones “<ϕ>~6.2 nm”. 相似文献
13.
Laser exposure of a suspension of either gold or palladium nanoparticles in aqueous solutions of UO2Cl2 of natural isotope abundance was experimentally studied. Picosecond Nd:YAG lasers at peak power of 1011–1013 W/cm2 at the wavelength of 1.06–0.355 μm were used as well as a visible-range Cu vapor laser at a peak power of 1010 W/cm2. The composition of colloidal solutions before and after laser exposure was analyzed using atomic absorption and gamma spectroscopy
in the 0.06–1 MeV range of photon energy. Real-time gamma spectroscopy was used to characterize the kinetics of nuclear reactions
during laser exposure. It was found that laser exposure initiated nuclear reactions involving both 238U and 235U nuclei via different channels in H2O and D2O. The influence of saturation of both the liquid and nanoparticles by gaseous H2 and D2 on the kinetics of nuclear transformations was found. Possible mechanisms of observed processes are discussed. 相似文献
14.
C.S. Rout K. Ganesh A. Govindaraj C.N.R. Rao 《Applied Physics A: Materials Science & Processing》2006,85(3):241-246
Sensing characteristics of ZnO, In2O3 and WO3 nanowires have been investigated for the three nitrogen oxides, NO2, NO and N2O. In2O3 nanowires of ∼20 nm diameter prepared by using porous alumina membranes are found to have a sensitivity (defined as the ratio of the sensor resistance in the gas concerned to that in air) of about 60 for 10 ppm of all the three gases at a relatively low temperature of 150 °C. The response and recovery times are around 20 s. The sensitivity of these In2O3 nanowires is around 40 for 0.1 ppm of NO2 and N2O at 150 °C. WO3 nanowires of 5–15 nm diameter, prepared by the solvothermal process show a sensitivity of 20–25 for 10 ppm of the three nitrogen oxides at 250 °C. The response and recovery times are 10 s and 60 s, respectively. The sensitivity is around 10 for 0.1 ppm of NO2 at 250 °C. The sensitivity of In2O3 and WO3 nanowires is not affected by humidity even up to 90% relative humidity. The study also reveals that the sensing mechanism for the three nitrogen oxides have a commonality in that the desorption of oxygen is a crucial step in all the cases. PACS 07.07.Df; 85.35.-p; 82.35.Np 相似文献
15.
《Proceedings of the Combustion Institute》2023,39(4):4365-4375
The interaction between ammonia (NH3) and nitric oxide (NO) at high temperatures is studied in this work using a shock tube combined with laser absorption diagnostics. The system simultaneously measured the NH3 and NO time-histories during the reaction processes of the shock-heated NH3/NO/CO/Ar mixtures (NH3:NO ≈ 0.9:1.0 and 1.4:1.0). The absorption cross-sections of NH3 near 1122.10 cm–1 and NO at 1900.52 cm–1 (characterized in this study) were used for measuring NH3 and NO time-histories with the temperature measured by two CO absorption lines. The measured NH3 and NO time-histories at 1614–1968 K and 2.4–2.8 atm were compared with predictions of seven recent kinetics models. The predictions that based on different mechanisms are very different and the measured profiles are within the range of the predictions. The Glarborg, NUI Galway Syngas-NOx, and Mathieu mechanisms give the closest predictions to the measurements. Kinetics analyses indicate that the NH3 and NO consumption rates are extremely sensitive to the rate constants and branching ratio of NH2 + NO = N2 + H2O and NH2 + NO = NNH + OH, which are more reliably represented in the Glarborg and NUI Galway Syngas-NOx mechanisms. The performances of Glarborg mechanisms at lower initial temperatures can be apparently improved by revising the rate constants and branching ratio of NH2 + NO = N2 + H2O and NH2 + NO = NNH + OH. These two reactions are also the primary pathways for NO reduction and NH3 is mainly consumed via NH3 + OH = NH2 + H2O and NH3 + H = NH2 + H2. Trace amounts of NO2 and N2O impurities decompose to form O radical followed by the generation of OH radical via H-abstraction reactions, which significantly affects the predictions of NH3 and NO according to kinetics analyses. 相似文献
16.
The radiation spectra of plasma in the region of 130–350 nm and the intensities of the 175-nm ArCl, 193-nm ArF, and 258-nm
Cl2 bands produced in the transverse volume discharge on a mixture of Ar/CF2Cl2 = (1–15)/(0.008–0.150) kPa are investigated. The discharge is shown to be a multiwave source of UV-VUV radiation on transitions
of ArCl, ArF, and Cl2 molecules. The optimum content of Freon-12 molecules is 0.008–0.010 kPa and that of argon atoms 10–15 kPa. The ratio of the
intensities of the ArCl (B-X) and ArF (B-X) bands is 10, which is approximately equal to the ratio of concentrations of [Cl−] and [F−] ions, which are formed in the reaction of dissociative electron attachment to CF2Cl2 molecules. The service life of a radiator with λ = 175 nm of ArCl on one mixture in a gas-static mode is not greater than
5·103 pulses.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 3, pp. 407–408, May–June, 2000. 相似文献
17.
In this paper it is shown that to achieve a maximum efficiency and high output energy of an ArF (193 nm) excimer laser, one
should use optimal pump intensity. It has been shown experimentally that the optimal pump intensity for an ArF excimer laser
with the mixture of He:Ar:F2 has a value of 4.5–5.0 MW/cm3. The results of an experimental study of the pump and active medium parameters effect on the efficiency and output energy
of the ArF excimer laser on the mixture of He:Ar:F2 are presented. To provide high pump intensity of an active medium, the excitation scheme of the LC-inverter type has been used where the current return conductor inductance had been increased from 30 to 80 nH. This allows
the pump to achieve levels of intensity above 5.0 MW/cm3. By using the pump intensity of 5.0 MW/cm3 in an active medium of He:Ar:F2–79.7:20:0.3 at total pressure of 2.4 atm, we are the first to obtain the output energy of 1.3 J at the total efficiency of
2.0%. The pulse duration (FWHM) was 15±1 ns and the peak pulse power was 85 MW.
PACS 42.55.Lt; 42.60.Lh 相似文献
18.
Béla Hopp Tomi Smausz Bence Papdi Zsolt Bor András Szabó Lajos Kolozsvári Costas Fotakis Antal Nógrádi 《Applied Physics A: Materials Science & Processing》2008,93(1):45-49
In the production of biosensors or artificial tissues a basic step is the immobilization of living cells along the required
pattern. In this paper the ability of some promising laser-based methods to influence the interaction between cells and various
surfaces is presented.
In the first set of experiments laser-induced patterned photochemical modification of polymer foils was used to achieve guided
adherence and growth of cells to the modified areas: (a) Polytetrafluoroethylene was irradiated with ArF excimer laser (λ=193 nm, FWHM=20 ns, F=9 mJ/cm2) in presence of triethylene–tetramine liquid photoreagent; (b) a thin carbon layer was produced by KrF excimer laser (λ=248 nm, FWHM=30 ns, F=35 mJ/cm2) irradiation on polyimide surface to influence the cell adherence. It was found that the incorporation of amine groups in
the PTFE polymer chain instead of the fluorine atoms can both promote and prevent the adherence of living cells (depending
on the applied cell types) on the treated surfaces, while the laser generated carbon layer on polyimide surface did not effectively
improve adherence.
Our attempts to influence the cell adherence by morphological modifications created by ArF laser irradiation onto polyethylene–terephtalate
surface showed a surface–roughness dependence. This method was effective only when the Ra roughness parameter of the developed
structure did not exceed the 0.1 micrometer value.
Pulsed laser deposition with femtosecond KrF excimer lasers (F=2.2 J/cm2) was effectively used to deposit structured thin films from biomaterials (endothelial cell growth supplement and collagen
embedded in starch matrix) to promote the adherence and growth of cells.
These results present evidence that some surface can be successfully altered to induce guided cell growth. 相似文献
19.
Gold electrodes with known contact geometries were studied using impedance spectroscopy. From these data it was possible to
determine the specific polarisation conductivity per unit length of three-phase boundary (TPB). The values were found to be
(3÷22)×10−4 S·cm−1 dependent on the electrode history in pure oxygen at 977 °C and 2×10−6 S·cm−1 at 977 °C in “pure” hydrogen (PO2=10−20 atm at 1001 °C). The results are compared with previous data obtained for platinum electrodes. 相似文献
20.
V.A. Kapitanov Yu.N. Ponomarev K. Song H.K. Cha J. Lee 《Applied physics. B, Lasers and optics》2001,73(7):745-750
The results of theoretical and experimental studies of sensitivity of a resonant photoacoustic Helmholtz resonator detector
for gas flowing through a photoacoustic cell under reduced pressure are presented. The measurements of the sensitivity and
ultimate sensitivity of the differential photoacoustic cell were performed with a near-IR room-temperature diode laser using
the well-known H2O absorption line (12496.1056 cm-1) as a reference. The measured value of the sensitivity (6–17 Pa W m-1) is in satisfactory agreement with the calculated one, which equals 6–35 Pa W m-1. The obtained value of the ultimate sensitivity ((3–5)×10-7 W m-1 Hz-1/2) provides measurements of the concentration of molecules at the ppb–ppm level.
Received: 19 April 2001 / Revised version: 18 September 2001 / Published online: 7 November 2001 相似文献