共查询到20条相似文献,搜索用时 31 毫秒
1.
M.B. Pushkarsky M.E. Webber O. Baghdassarian L.R. Narasimhan C.K.N. Patel 《Applied physics. B, Lasers and optics》2002,75(2-3):391-396
An industrial trace-ammonia sensor based on photoacoustic spectroscopy and CO2 lasers has been developed for measuring ammonia with a 1σ detection limit of 220 parts-per-trillion (ppt) in an integration
time of 30 s. The instrument response time for measuring ammonia was 200 s, limited by adsorption effects due to the polar
nature of ammonia. The minimum detectable fractional absorbance was 2.0×10-7, and the minimum normalized detectable absorption coefficient for this system was 2.4×10-7 W cm-1/z. The 9R(30) transition of the CO2 laser at 9.22 μm with 2 W of output power was used to probe the strong sR(5,K) multiplet of ammonia at the same wavelength. This sensor was demonstrated with an optically multiplexed configuration
for simultaneous measurement in four cells.
Received: 3 April 2002 / Revised version: 31 May 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-310/458-0171, E-mail: webber@pranalytica.com 相似文献
2.
F. Kühnemann M. Wolfertz S. Arnold M. Lagemann A. Popp G. Schüler A. Jux W. Boland 《Applied physics. B, Lasers and optics》2002,75(2-3):397-403
A photoacoustic spectrometer for the simultaneous detection of isoprene and the deuterated species [4,4-2H]-2-methyl-1,3-butadiene (isoprene-d2) is presented. Using a sealed-off 13CO2 laser a single-component detection limit of 400 ppt (isoprene) and 600 ppt (isoprene-d2) was achieved. Simultaneous monitoring of both compounds allowed the detection of labelling levels down to 6% (isoprene-d2 in total isoprene) with a time resolution of 3 min.
In emission studies with Eucalyptus globulus, the deuterated precursor [4,4-2H]-1-deoxy-D-xylulose was fed to a leaf through the transpiration stream. Emission of isoprene-d2 started as early as 10 min after application of the precursor.
Received: 3 May 2002 / Revised version: 31 May 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +49-228/733474, E-mail: frank.kuehnemann@iap.uni-bonn.de 相似文献
3.
An investigation was carried out on Renaissance lustre-decorated majolica shards, found during excavations made in Umbria
(central Italy) and defined by experts, on the ground of the surface decoration, as imitations of the Hispano-Moresque style.
A comparison between this particular kind of samples, produced in central Italy, and some Hispano-Moresque lustre shards has
been performed. The ceramic bodies as well as the lustred surfaces have been analysed by means of several techniques: inductively
coupled plasma optical emission spectrometry, X-ray diffraction (XRD), atomic absorption spectrometry with electrothermal
atomisation and scanning electron microscopy. By means of XRD analysis the presence of cosalite (Pb2Bi2S5) has been disclosed in the Italian lustre decorations but was not observed in the Hispano-Moresque ones. A hypothesis has
been made, considering bismuth as a discriminating element, between lustres produced in central Italy and the Hispano-Moresque
ones. We thought that the Italian artisans were able to manage the use of bismuth. Therefore a recipe, quite similar to the
one employed by the Spanish artisans, was used by the Italian ceramists if their aim was to imitate the Hispano-Moresque style.
Received: 4 November 2002 / Accepted: 6 November 2002 / Published online: 28 March 2003
RID="*"
ID="*"Corresponding author. Fax: +39-06/9067-2316, E-mail: pad@mlib.cnr.it 相似文献
4.
Ta/NiOx/Ni81Fe19/Ta films were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field Hex and the coercivity Hc of NiOx/Ni81Fe19 as a function of the ratio of Ar to O2 during the deposition process were studied. The composition and the chemical states in the interface region of NiOx/NiFe were also investigated using X-ray photoelectron spectroscopy (XPS) and the peak decomposition technique. The results
show that the ratio of Ar to O2 has a great effect on the chemical states of nickel in NiOx films. The exchange coupling field Hex and the coercivity Hc of Ta/NiOx/Ni81Fe19/Ta are thus seriously affected. XPS is shown to be a powerful tool for characterizing magnetic films.
Received: 18 July 2001 / Accepted: 21 December 2001 / Published online: 3 June 2002
RID="*"
ID="*"Corresponding author. Fax: +86-010/6232-7283, E-mail: guanghua_yu@263.net 相似文献
5.
G. Totschnig M. Lackner R. Shau M. Ortsiefer J. Rosskopf M.C. Amann F. Winter 《Applied physics. B, Lasers and optics》2003,76(5):603-608
A single-frequency VCSEL has been used for the first time for high-resolution spectroscopy near 1.5 μm. The incorporated buried-tunnel-junction
technology enabled the realization of a long-wavelength InGaAlAs/InP VCSEL with low threshold current (0.925 mA), high output
powers (0.576 mW) and low series resistance (60 Ω). The high-speed tuning capability of the long-wavelength VCSEL was investigated
and used to conduct high-speed absorption spectroscopy. The peak tuning speed was measured to be 3.4 cm-1/μs and a 4.5-cm-1-wide NH3 spectrum was recorded in 2 μs. The VCSEL was used to measure highly resolved low-pressure spectra for pressures ranging from
9.6 mbar to 1 bar. The measured Doppler-broadened linewidth of 0.02 cm-1 agrees within 3% with the theoretical calculations. The availability and various advantages of 1.3–2-μm single-frequency
VCSELs as compared to edge-emitting diode lasers, such as a large current tuning range even at very high tuning frequencies,
and low production costs, should significantly expand the application fields for near-infrared laser gas sensors.
Received: 17 July 2002 / Revised version: 4 December 2002 / Published online: 12 May 2003
RID="*"
ID="*"Corresponding author. Fax: +43-1/58801-15999, E-mail: Gerhard@Totschnig.com 相似文献
6.
R. Denk K. Piglmayer D. Bäuerle 《Applied Physics A: Materials Science & Processing》2003,76(4):549-550
A regular lattice of a-SiO2 microspheres on a quartz support is used as a microlens array for laser-induced surface patterning by etching and deposition
of W in atmospheres of WF6 and WF6+H2, respectively.
Received: 22 July 2002 / Accepted: 30 July 2002 / Published online: 4 December 2002
RID="*"
ID="*"Corresponding author. Fax: +43-732/2468-9242, Email: dieter.baeuerle@jku.at 相似文献
7.
J.W. Yoon T. Sasaki N. Koshizaki 《Applied Physics A: Materials Science & Processing》2003,76(4):641-643
Nanocrystalline thin films of complex oxides such as BaTiO3 and LaFeO3 were prepared by pulsed laser ablation without substrate heating. Targets under various Ar pressures were irradiated using
an ArF excimer laser. The off-axis configuration of targets and substrates was used to synthesize the films. The crystallinity
and chemical composition of the deposited films were strongly dependent on the processing Ar gas pressure. In case of BaTiO3, the film deposited at 10 Pa was a single phase of BaTiO3 with a crystallite size around 7.2 nm. With increasing Ar pressure to 200 Pa, XRD peaks of BaTiO3 as well as BaCO3 were observed. The by-products could be due to reaction with carbon dioxide in air after taking the sample out of the chamber.
For LaFeO3, the films deposited under 50 to 200 Pa had a single phase with a crystallite size below 10 nm. When the Ar pressure exceeded
100 Pa, the crystallite size tended to decrease for both BaTiO3 and LaFeO3, which could be due to formation of aggregated nanoparticles. Below 10 Pa, oxygen deficiency was observed. Over 50 Pa, the
atomic concentration of all the constituent elements was almost constant, especially the [Ba]/[Ti] and [La]/[Fe] ratios, which
were nearly unity.
Received: 19 June 2002 / Accepted: 24 June 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +81-298/61-6355, E-mail: yoon-jw@aist.go.jp 相似文献
8.
D.D. Nelson J.H. Shorter J.B. McManus M.S. Zahniser 《Applied physics. B, Lasers and optics》2002,75(2-3):343-350
Non-cryogenic, laser-absorption spectroscopy in the mid-infrared has wide applications for practical detection of trace gases
in the atmosphere. We report measurements of nitric oxide in air with a detection limit less than 1 nmole/mole (<1 ppbv) using
a thermoelectrically cooled quantum cascade laser operated in pulsed mode at 5.26 μm and coupled to a 210-m path length multiple-pass
absorption cell at reduced pressure (50 Torr). The sensitivity of the system is enhanced by operating under pulsing conditions
which reduce the laser line width to 0.010 cm-1 (300 MHz) HWHM, and by normalizing pulse-to-pulse intensity variations with temporal gating on a single HgCdTe detector.
The system is demonstrated by detecting nitric oxide in outside air and comparing results to a conventional tunable diode
laser spectrometer sampling from a common inlet. A detection precision of 0.12 ppb Hz-1/2 is achieved with a liquid-nitrogen-cooled detector. This detection precision corresponds to an absorbance precision of 1×10-5 Hz-1/2 or an absorbance precision per unit path length of 5×10-10 cm-1 Hz-1/2. A precision of 0.3 ppb Hz-1/2 is obtained using a thermoelectrically cooled detector, which allows continuous unattended operation over extended time periods
with a totally cryogen-free instrument.
Received: 1 May 2002 / Revised version: 6 June 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-978/663-4918, E-mail: ddn@aerodyne.com 相似文献
9.
S.-H. Jung M.-R. Kim S.-H. Jeong S.-U. Kim O.-J. Lee K.-H. Lee J.-H. Suh C.-K. Park 《Applied Physics A: Materials Science & Processing》2003,76(2):285-286
Synthesis of multi-walled carbon nanotubes (MWNTs) by arc discharge in liquid nitrogen is reported. As liquid nitrogen substituted
both vacuum and cooling systems, high-quality MWNTs were produced at a low cost. The content of the MWNTs can be as high as
70% of the reaction product. Auger-spectroscopy analysis revealed that no nitrogen is incorporated in the MWNTs. This method
can be an economical route for the mass production of highly crystalline MWNTs.
Received: 5 July 2002 / Accepted: 8 July 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +82-54/279-8298, E-mail: ce20047@postech.ac.kr 相似文献
10.
The progress in the development of a sensor for the detection of trace air constituents to monitor spacecraft air quality
is reported. A continuous-wave (cw), external-cavity tunable diode laser centered at 1.55 μm is used to pump an optical cavity
absorption cell in cw-cavity ringdown spectroscopy (cw-CRDS). Preliminary results are presented that demonstrate the sensitivity,
selectivity and reproducibility of this method. Detection limits of 2.0 ppm for CO, 2.5 ppm for CO2, 1.8 ppm for H2O, 19.4 ppb for NH3, 7.9 ppb for HCN and 4.0 ppb for C2H2 are calculated.
Received: 3 April 2002 / Revised version: 3 June 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-202/994-5873, E-mail: Houston@gwu.edu 相似文献
11.
X. Liu Q. Lu P. Liu M. Zhao Z. Wang M. Ying F. Li L. Qin 《Applied Physics A: Materials Science & Processing》2003,76(2):273-275
Range distributions for bismuth ions implanted in AgGaSe2 in the energy range 80–300 keV were investigated by using 2.1-MeV He2+ Rutherford backscattering spectrometry (RBS). A convolution calculation method was used to extract the true distributions
of bismuth from the measured RBS spectra. The range distribution parameters, Rp and ΔRp, were obtained and compared with those obtained from Monte Carlo simulation. The experimental Rp values agree with the Monte Carlo simulation values very well, but the experimental ΔRp values are systematically larger than those from the theoretical simulation.
Received: 28 January 2002 / Accepted: 11 April 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +86-531/856-5167, E-mail: xdliu@sdu.edu.cn 相似文献
12.
Sensitive absorption measurements in the near-infrared region using off-axis integrated-cavity-output spectroscopy 总被引:3,自引:0,他引:3
A novel instrument that employs a high-finesse optical cavity as an absorption cell has been developed for sensitive measurements
of gas mixing ratios using near-infrared diode lasers and absorption-spectroscopy techniques. The instrument employs an off-axis
trajectory of the laser beam through the cell to yield an effective optical path length of several kilometers without significant
unwanted effects due to cavity resonances. As a result, a minimum detectable absorption of approximately 1.4×10-5 over an effective optical path of 4.2 km was obtained in a 1.1-Hz detection bandwidth to yield a detection sensitivity of
approximately 3.1×10-11 cm-1 Hz-1/2. The instrument has been used for sensitive measurements of CO, CH4, C2H2 and NH3.
Received: 6 May 2002 / Revised version: 31 May 2002 / Published online: 2 September 2002
RID="*"
ID="*"Corresponding author. Fax: +1-650/965-7074, E-mail: d.baer@lgrinc.com 相似文献
13.
Oxygen plasma and high pressure H2O vapor heat treatment were applied to fabrication of n-channel polycrystalline silicon thin film transistors (poly-Si TFTs).
13.56 MHz-oxygen-plasma treatment at 250 °C, 100 W for 5 min effectively reduced defect states of 25-nm-thick silicon films
crystallized by 30 ns-pulsed XeCl excimer laser irradiation. 1.3×106-Pa-H2O vapor heat treatment at 260 °C for 3 h was carried out in order to improve electrical properties of SiOx gate insulators and SiOx/Si interfaces. A carrier mobility of 470 cm2/V s and a low threshold voltage of 1.8 V were achieved for TFTs fabricated with crystallization at 285 mJ/cm2.
Received: 18 November 2002 / Accepted: 25 November 2002 / Published online: 11 April 2003
RID="*"
ID="*"Corresponding author. Fax: +81-42/388-7109, E-mail: tsamesim@cc.tuat.ac.jp 相似文献
14.
R.L.D. Whitby W.K. Hsu C.B. Boothroyd K.S. Brigatti H.W. Kroto D.R.M. Walton 《Applied Physics A: Materials Science & Processing》2003,76(4):527-532
Time-dependent powder X-ray-diffraction analyses reveal that the conversion of WO3 into WS2 on carbon nanotube surfaces in the presence of H2S is a one-step process. The WS2 layers grow simultaneously along the tube in the radial and axial directions.
Received: 17 June 2002 / Accepted: 19 June 2002 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. Fax: +44-1273/677-196, E-mail: d.walton@sussex.ac.uk 相似文献
15.
Tuning and stability of a continuous-wave mid-infrared high-power single resonant optical parametric oscillator 总被引:1,自引:0,他引:1
M.M.J.W. van Herpen S. Li S.E. Bisson S. te Lintel Hekkert F.J.M. Harren 《Applied physics. B, Lasers and optics》2002,75(2-3):329-333
A 2.2-W continuous-wave, continuously tunable, single-frequency OPO has been developed in the 3.0–3.8 μm wavelength range
for the detection of molecular trace gasses. The oscillation threshold, output power and stability of the single resonant
OPO were improved by optimizing pump beam waist and OPO cavity length. Both air-spaced and solid etalons were tested to frequency
stabilize and tune the OPO, from which the solid etalon gave a better performance. Temperature oscillations in the PPLN crystal
caused oscillations in the idler wavelength of less than 200 MHz over 300 s; the short-term stability was less than 3 MHz
over 1 s. The high laser power, in combination with photoacoustic spectroscopy, achieved a detection limit of 10 parts-per-trillion
for ethane in nitrogen.
Received: 9 April 2002 / Revised version: 14 June 2002 / Published online: 2 September 2002
RID="*"
ID="*"Corresponding author. Fax:+31-24/3653311, E-Mail: maartenh@sci.kun.nl 相似文献
16.
Copper nanowire arrays for infrared polarizer 总被引:10,自引:0,他引:10
Y.T. Pang G.W. Meng Y. Zhang Q. Fang L.D. Zhang 《Applied Physics A: Materials Science & Processing》2003,76(4):533-536
A micropolarizer of copper nanowire arrays within anodic alumina membrane (AAM) was fabricated by anodization of pure Al foil
and electrodeposition of Cu, respectively. X-ray diffraction, scanning electron microscopy and transmission electron microscopy
investigations reveal that the ordered Cu nanowires are essentially single crystal, and have an average diameter of 90 nm.
Spectrophotometer measurements show that the copper nanowire arrays embedded in AAM can only transmit polarized light vertical
to the wires. An extinction ratio of 24 to 32 dB and an average insertion loss of 0.5 dB in the wavelength range of 1 to 2.2 μm
were obtained, respectively. Therefore Cu nanowire/AAM can be used as a wire grid type micropolarizer.
Received: 28 January 2002 / Accepted:17 May 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +86-551/559-1434, E-mail: ytpang@263.net 相似文献
17.
Laser-induced fluorescence is used to detect and record profiles of acetylene formed as an intermediate species in 10-Torr
premixed propane and methane flames. In low-temperature regions of the flames, excitation spectra confirm acetylene as the
spectral carrier. The spectra of acetylene overlap those of O2 and NO in terms of both excitation and detection wavelengths, however, acetylene can be detected with relatively little interference
in the vicinity of 228 nm, using a detection wavelength of 260 nm. The fluorescence lifetime of acetylene in the flame conditions
studied is approximately 20 ns, much shorter than the radiative lifetime, due to a high quenching rate for all the colliders
investigated. This can be exploited in low-pressure flames to avoid interference from acetylene in monitoring nitric oxide.
The acetylene mole fraction in propane flames reaches its peak value at nearly the same location as that of HCO, slightly
closer to the burner than the peak CH mole fraction. The acetylene fluorescence signal is easily detected in propane flames
over equivalence ratios from 0.6 to 1.2, although it increases under fuel-rich conditions. In methane flames, the acetylene
signal is much weaker and is undetectable for fuel-lean conditions.
Received: 5 August 2002 / Revised version: 30 September 2002 / Published online: 20 December 2002
RID="*"
ID="*"Corresponding author. Fax: +1-202/767-1716, E-mail: brad@code6185.nrl.navy.mil 相似文献
18.
Ultrahigh-efficiency TEM00 operation is demonstrated in a diode-pumped Nd:YVO4 laser in a bounce amplifier geometry using a specially designed astigmatically optimised cavity configuration. Optical efficiency
>68% is demonstrated and up to 27.1 W of output power for multimode operation. For single-mode TEM00 operation, an output power of 23.1 W for 39.5 W of diode pumping was produced with beam propagation parameters of Mx
2=1.3 and My
2=1.1.
Received: 10 October 2002 / Revised version: 9 December 2002 / Published online: 19 March 2003
RID="*"
ID="*"Corresponding author. Fax: +44-20/7594-7744, E-mail: a.minassian@ic.ac.uk 相似文献
19.
T.J. Kulp S.E. Bisson R.P. Bambha T.A. Reichardt U.-B. Goers K.W. Aniolek D.A.V. Kliner B.A. Richman K.M. Armstrong R. Sommers R. Schmitt P.E. Powers O. Levi T. Pinguet M. Fejer J.P. Koplow L. Goldberg T.G. McRae 《Applied physics. B, Lasers and optics》2002,75(2-3):317-327
Quasi-phase-matched (QPM) materials allow the generation of spectroscopically useful infrared radiation in an efficient and
broadly tunable format. Here, we describe several applications of QPM-based light sources to remote and local chemical sensing.
The remote systems are gas imagers that employ a fiber-pumped continuous-wave optical parametric oscillator or a microlaser-pumped,
diode-seeded optical parametric amplifier as the illumination source. Technology described for local sensing includes a cavity
ring down spectrometer that employs a novel optical parametric generator–amplifier to achieve ≥350 cm-1 of contiguous tuning and a long-wave infrared light source based on QPM GaAs. In each case the use of QPM materials in conjunction
with effective pump sources instills simplicity and ruggedness into the sensing systems.
Received: 15 April 2002 / Revised version: 6 June 2002 / Published online: 12 September 2002
RID="*"
ID="*"Corresponding author. Fax: +1-925/294-2595, E-mail: tjkulp@sandia.gov
RID="**"
ID="**"Present address: Corning Inc., Corning, NY 14831, USA
RID="*"
ID="*"Present address: Corning Inc., Corning, NY 14831, USA
RID="**"
ID="**"Present address: Blue Leaf Networks, Sunnyvale, CA 94086, USA
RID="***"
ID="***"Present address: Sandia National Laboratories, Albuquerque, NM 87185, USA 相似文献
20.
A pulsed optical parametric oscillator (OPO) operated in an optical cavity with a grazing-incidence grating configuration
(GIOPO) was used for sensitive photoacoustic detection of trace quantities of dinitrogen oxide (N2O). The (ν1+ν3) combination vibration band of N2O was excited with the idler beam of the GIOPO at 2.86 μm using an optical cavity optimized for the idler beam. The linewidth
of the GIOPO could be reduced to 0.4 cm-1, allowing the rotational structure of the absorption spectrum to be resolved. A concentration sensitivity (signal-to-noise
ratio=3) of 60 parts in 109 by volume (60 ppb V) N2O in synthetic air was obtained. This may be sufficient for continuous monitoring of N2O in the atmosphere.
Received: 29 April 2002 / Revised version: 4 June 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +49-6221/54-4255, E-mail: peter.hess@urz.uni-heidelberg.de 相似文献