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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.
The Stark effect in ammonia has been theoretically and experimentally analyzed using lead salt tunable diode laser absorption spectroscopy and CO2 laser absorption spectroscopy of several absorption lines around 1050 cm–1 applied to an all-optical sensor for measuring of electric field strength. Measurements of the Stark splitting effect of theaR(5,K) ammonia lines forK=1–5 as well as for the sR(3,K) lines forK=0–3 have been made at Doppler broadening pressures and for several different electric field strengths. Theoretical electric field dependent energy levels have been evaluated by diagonalization of a 6×6 energy matrix constructed using both electric field independent and dependent terms. From the theoretical analysis the resolution can be predicted and optimized both in the Doppler broadened and in the pressure broadened regimes. The predicted resolution is 0.5% at an electric field strength of 20 kV/cm. The theoretical calculations and the experimental data recorded with the tunable diode laser system were compared with independent measurements made with a CO2 laser system. The agreement between experimentally recorded and theoretically calculated spectra is good which indicates that the theoretical model is satisfactory for our purposes. The contribution from the normally forbidden ssR(5, 3) ammonia line to the absorption at theP(12) CO2 laser line in the 9 m band is briefly discussed. 相似文献
3.
V. Yu. Baranov S. A. Kazakov V. D. Pis'menny A. I. Starodubtsev E. P. Velikhov Yu. A. Gorokhov V. S. Letokhov A. P. Dyad'kin A. Z. Grasiuk B. I. Vasil'yev 《Applied Physics A: Materials Science & Processing》1978,17(3):317-320
Design and operating caracteristics of high pulse repetition rate NH3 laser producing up to 20 W of average output power are described. The NH3 laser, operating in the 12–13 μm region was optically pumped with a high pulse repetition rate TEA CO2 laser. Dependences of the NH3 laser output on the pump energy, ammonia and buffer gas pressures and pulse repetition rate have been studied. The conversion
efficiency of up to 16% has been received. 相似文献
4.
M. Redon C. Gastaud M. Fourrier 《International Journal of Infrared and Millimeter Waves》1980,1(1):95-109
We report fifty seven CW FIR emissions observed in NH3, by resonant pumping with a CO2 laser. Exact coincidences between IR absorption lines of the gas and emission lines of the CO2 laser have been carried out by Stark tuning. IR frequency shifts, up to 30 GHz, have allowed the pumping of forty three NH3 transitions.These FIR emissions correspond to thirty one different wavelengths in the 50–400 m range; eighteen ones of them are new emitted wavelengths by pumping with the CO2 laser. 相似文献
5.
S. Kuribayashi T. Tomimasu S. Kawanishi S. Arai 《Applied physics. B, Lasers and optics》1997,65(3):393-398
2 . The laser generates an intense infrared macropulse with a duration of 17 μs; the macropulse consists of a train of 380 micropulses,
each of which has a duration of a few picoseconds. The fluence of a macropulse was estimated to be about 16 Jcm-2 at a beam waist. Peak wavelengths were set in the range of 9–10 μm. The macropulse induced the IRMPD of 1 and 5 Torr CHBrF2; most of molecules in the focal region seemed to decompose at a wavelength of 9.3 μm. The mechanism is the initial decomposition
of CHBrF2 to CF2 and HBr, followed by the dimerization of CF2 to form C2F4. The decomposition was found to be isotopically selective at 9.7 μm; the final product C2F4 had a 13C atomic fraction of 6%. Th
e addition of CO2 to CHBrF2 significantly decreased the yield of C2F4. vibrationally excited CHBrF2 molecules produced by laser pulses were efficiently deactivated by CO2 molecules.
Received: 7 October 1996 相似文献
6.
D. A. Long M. Okumura C. E. Miller J. T. Hodges 《Applied physics. B, Lasers and optics》2011,105(2):471-477
Carbon dioxide (CO2) isotopic ratios on samples of pure CO2 were measured in the 1.6 μm wavelength region using the frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) technique.
We present CO2 absorption spectra with peak signal-to-noise ratios as high as 28,000:1. Measured single-spectrum signal-to-noise ratios
were as high as 8900:1, 10,000:1, and 1700:1 for 13C/12C, 18O/16O, and 17O/16O, respectively. In addition, we demonstrate the importance of utilizing the Galatry line profile in the spectrum analysis.
The use of the Voigt line profile, which neglects the observed collisional narrowing, leads to large systematic errors which
are transition-dependent and vary with temperature and pressure. While the relatively low intensities of CO2 transitions near λ=1.6 μm make this spectral region non-optimal, the sensitivity and stability of FS-CRDS enabled measurement precision of pure
CO2 samples which are comparable to those of other optical techniques which operate at far more propitious wavelengths. These
results indicate that a FS-CRDS spectrometer designed to probe CO2 bands near wavelengths of 2.0 μm or 4.3 μm could achieve significantly improved precision over the present instrument and
likely be competitive with mass spectrometric methods. 相似文献
7.
Space-borne remote sensing of CO2, CH4, and N2O by integrated path differential absorption lidar: a sensitivity analysis 总被引:2,自引:0,他引:2
G. Ehret C. Kiemle M. Wirth A. Amediek A. Fix S. Houweling 《Applied physics. B, Lasers and optics》2008,90(3-4):593-608
CO2, CH4, and N2O are recognised as the most important greenhouse gases, the concentrations of which increase rapidly through human activities.
Space-borne integrated path differential absorption lidar allows global observations at day and night over land and water
surfaces in all climates. In this study we investigate potential sources of measurement errors and compare them with the scientific
requirements. Our simulations reveal that moderate-size instruments in terms of telescope aperture (0.5–1.5 m) and laser average
power (0.4–4 W) potentially have a low random error of the greenhouse gas column which is 0.2% for CO2 and 0.4% for CH4 for soundings at 1.6 μm, 0.4% for CO2 at 2.1 μm, 0.6% for CH4 at 2.3 μm, and 0.3% for N2O at 3.9 μm. Coherent detection instruments are generally limited by speckle noise, while direct detection instruments suffer
from high detector noise using current technology. The wavelength selection in the vicinity of the absorption line is critical
as it controls the height region of highest sensitivity, the temperature cross-sensitivity, and the demands on frequency stability.
For CO2, an error budget of 0.08% is derived from our analysis of the sources of systematic errors. Among them, the frequency stability
of ± 0.3 MHz for the laser transmitter and spectral purity of 99.9% in conjunction with a narrow-band spectral filter of 1 GHz
(FWHM) are identified to be challenging instrument requirements for a direct detection CO2 system operating at 1.6 μm.
PACS 42.68.Wt; 95.75.Qr 相似文献
8.
M. Jackson T.J. Garrod M. Ramberg A. Stokes 《Applied physics. B, Lasers and optics》2005,81(8):1067-1069
A recently improved three-laser heterodyne system was used to frequency measure ten previously observed optically pumped far-infrared
(FIR) laser emissions from the partially deuterated methanol isotopologue CH2DOH. Also, a 64.0 μm FIR emission generated by the 9P32 line of the carbon dioxide (CO2) laser was discovered and frequency measured. These newly measured frequencies have fractional uncertainties on the order
of ±2×10-7 and correspond to laser wavelengths ranging from 42.6 to 152.7 μm. The offset frequency for the CO2 pump laser was measured for twenty-two CH2DOH FIR laser emissions.
PACS 07.57.Hm; 42.55Lt; 42.62.Eh 相似文献
9.
Li D. J. Yang G. L. Chen F. Xie J. J. Zhang L. M. Guo J. Shao C. L. Peng Z. Q. Lu Q. P. 《Laser Physics》2012,22(5):937-940
Stimulated rotational Raman scattering (SRRS) at multiwavelength pumped by TEA CO2 laser was demonstrated in this paper. Raman mediums were cooled by liquid-N2 and a multiple-pass cell (MPC) with 25 passes was designed and used. When the para-H2 was pumped by single-longitudinal-mode
(SLM) circular polarized TEA CO2 laser on 10P(20), 9P(20), and 10R(20), 50 mJ 16.95 μm, 350 mJ 14.44 μm, and 536 mJ 16.9 μm radiations were obtained, corresponding
to energy conversion efficiency of 1.2, 11.7, and 13.4%, respectively. When the ortho-D2 was pumped by CO2 laser on 10R(18), 108 mJ 12.57 μm Raman laser was obtained with energy conversion efficiency of 2.9%. 相似文献
10.
K.M. Evenson Q. Sanford C. Smith J. Sullivan D. Sutton E. Vershure M. Jackson 《Applied physics. B, Lasers and optics》2002,74(6):613-614
The partially deuterated isotopes of methanol, CH2DOH and CHD2OH, have been reinvestigated as sources of far-infrared (FIR) laser emissions using an optically pumped molecular laser (OPML)
system recently designed for wavelengths below 150 μm. With this system, 10 new FIR laser emissions from these isotopes ranging
from 32.8 to 174.6 μm have been discovered. This includes the shortest known OPML emission from CHD2OH, at 32.8 μm. These lines are reported with their operating pressure, polarizations relative to the CO2 pump laser and wavelengths, measured to ±0.5 μm. In addition, polarizations for three previously observed FIR laser lines
from CHD2OH were measured for the first time.
This paper is dedicated to the memory of Dr. K.M. Evenson, a pioneer in the field for his role in the development of optically
pumped molecular lasers and their use in laser frequency measurements and the laser magnetic resonance technique. His scientific
expertise, guidance, mentoring and friendship will be greatly missed.
Received: 27 March 2002 / Published online: 8 May 2002 相似文献
11.
A tunable diode laser (TDL) is used to measure the absorption spectra of the R46 through R54 transitions of the 20012←00001 band of CO2 near 2.0 μm (5000 cm−1) at room temperature and pressures to 10 atm (densities to 9.2 amagat). Spectra are recorded using direct absorption spectroscopy
and wavelength modulation spectroscopy with second-harmonic detection (WMS-2f) in a mixture containing 11% CO2 in air. The direct absorption spectra are influenced by non-Lorentzian effects including finite-duration collisions which
perturb far-wing absorption, and an empirical χ-function correction to the Voigt line shape is shown to greatly reduce error in the spectral model. WMS-2f spectra are shown
to be at least a factor of four less-influenced by non-Lorentzian effects in this region, making this approach more resistant
to errors in the far-wing line shape model and allowing a comparison between the spectral parameters of HITRAN and a new database
which includes pressure-induced shift coefficients. The implications of these measurements on practical, high-pressure CO2 sensor design are discussed. 相似文献
12.
M. Stanislawki J. Meister T. Mitra M.M. Ivanenko K. Zanger P. Hering 《Applied physics. B, Lasers and optics》2001,72(1):115-120
The Er:YAG and the CO2 laser are competitors in the field of hard tissue ablation. The use of Er:YAG lasers (2.94 μm, pulse length
L of 100 to 200 μs) show smaller areas of thermal defects then ‘‘superpulsed’’ CO2 lasers with pulse lengths of approximately 100 μs. Only the development of a Q-switched CO2 laser (9.6 μm, τL=250 ns) allowed for similar results. In this paper new results for the Er:YAG and the Q-switched CO2 laser under the influence of water spray will be presented. Several parameters are of special interest for these investigations:
the specific ablation energy, which shows a minimum for the CO2 laser at an energy density of 9 J/cm 2 and a broad shallow minimum in the range of 10 to 70 J/cm2 for the Er:YAG laser, and comparison of the cut-shape and depth. Surface effects and cutting velocity are discussed based
on SEM pictures.
Received: 19 July 2000 / Revised version: 1 November 2000 / Published online: 30 November 2000 相似文献
13.
T. Le Barbu B. Parvitte V. Zéninari I. Vinogradov O. Korablev G. Durry 《Applied physics. B, Lasers and optics》2006,82(1):133-140
A diode laser spectrometer was used in the laboratory to study H2O and CO2 line intensities and self-broadening coefficients around 1.877 μm. The spectral region ranging from 5327 cm-1 to 5329 cm-1, which is suitable for the in situ sensing of water vapor and carbon dioxide in the Martian atmosphere, was studied using
a distributed feedback GaInSb diode laser from Nanoplus GmbH. We have studied one line from the (011)←(000)band of H2O and two lines from the (0112)I←(000) band of CO2. The results of intensity and self-broadening measurements are compared to available databases, ab initio calculations and
previous experimental determinations. Finally, we discuss the current development of the tunable diode laser absorption spectrometer
instrument, a laser diode sensor devoted to the in situ measurement of H2O and CO2 in the Martian atmosphere.
PACS 07.57.Ty; 07.87.+v 相似文献
14.
J.C.S. Moraes O.P. Pizoletto A. Scalabrin M.D. Allen K.M. Evenson 《Applied physics. B, Lasers and optics》2001,72(2):241-244
We have reinvestigated 13CH3OH as a source of far-infrared (FIR) laser emission using a CO2 laser as a pumping source. Thirty new FIR laser lines in the range 36.5 μm to 202.6 μm were observed and characterized. Five
of them have wavelengths between 36.5 and 75 μm and have sufficient intensity to be used in LMR spectroscopy. Using Fourier-transform
spectroscopic data in the infrared (IR) and FIR regions we have determined the assignment for 10 FIR laser transitions and
predict nine frequencies for laser lines which have yet to be observed.
Received: 17 July 2000 / Published online: 6 December 2000 相似文献
15.
J. Reid J. Shewchun B. K. Garside 《Applied Physics A: Materials Science & Processing》1978,17(4):349-353
We report the first accurate measurements of the transition strengths and linewidths of the 00o2 9.4 μm sequence lines of CO2. This sequence band is found to be very similar to the regular 00o1 laser band, except for an experimentally determined factor of 1.89±0.12 increase in transition strength (if the CO2 molecule is treated as a simple harmonic oscillator the theoretical increase in transition strength is 2.0). The laser absorption
spectrometer used for these measurements can detect absorption coefficients in CO2 of ≈10−7 m−1, and we discuss the feasibility of using this sensitivity to monitor rare isotopic forms of CO2.
Work supported by the Department of National Health and Welfare, Environment Canada, Ontario Ministry of the Environment,
and Atmospheric Environment Service, Environment Canada. 相似文献
16.
《Applied physics. B, Lasers and optics》1981,24(1):33-38
We report infrared laser emission in the region of 3 to 5 μm from sodium vapour optically pumped by a pulsed dye laser with
wavelengths ranging from 585 to 610nm. Twophoton excitation processes are believed to be responsible for the primary excitation.
Both molecular transitions (4 to 5 μm) between high lying states, and atomic transitions (52
S
1/2−42
P
3/2,1/2 at 3.41 μm) have been identified. 相似文献
17.
In this paper we describe the construction of a monochromatic and frequency stabilized continuous wave (cw) source in the
5 μm region. It is built up by a cw single line, single-mode frequency and amplitude stabilized CO2 laser. This primary CO2 laser source is then frequency-doubled in a tellurium crystal using second harmonic generation (SHG). The obtained emission
is monochromatic (half-width 50 kHz). The frequency can be varied discreetly from 4.6 μm to 5.5 μ depending on the CO2 laser line chosen.
Equipe de recherche associée au CNRS No. 541 相似文献
18.
V. P. Zharov V. S. Letokhov E. A. Ryabov 《Applied Physics A: Materials Science & Processing》1977,12(1):15-17
A new detection method for absorption from excited vibrational states is suggested, based on optoacoustic detection of weak
absorption in a heated gas. Using this method CO2 laser radiation (λ=9.6 μm) absorption was investigated from excited vibrational states of CO2, BCl3, and BF3 molecules. 相似文献
19.
R. Peeters G. Berden A. Apituley G. Meijer 《Applied physics. B, Lasers and optics》2000,71(2):231-236
A compact open-path optical ammonia detector is developed. A tunable external-cavity diode laser operating at 1.5 μm is used
to probe absorptions of ammonia via the cavity-enhanced absorption (CEA) technique. The detector is tested in a climate chamber.
The sensitivity and linearity of this system are studied for ammonia and water at atmospheric pressure. A cluster of closely
spaced rovibrational overtone and combination band transitions, observed as one broad absorption feature, is used for the
detection of ammonia. On these molecular transitions a detection limit of 100 ppb (1 s) is determined. The ammonia measurements
are calibrated independently with a chemiluminescence monitor. Compared to other optical open-path detection methods in the
1–2 μm region, the present result shows an improved sensitivity for contactless ammonia detection by over one order of magnitude.
Using the same set-up, a detection limit of 100 ppm (1 s) is determined for the detection of water at atmospheric pressure.
Received: 19 January 2000 / Revised version: 6 March 2000 / Published online: 7 June 2000 相似文献
20.
S. Banerjee K. Miyata K. Kato N. Saito S. Wada 《Applied physics. B, Lasers and optics》2007,87(1):101-103
AgGa1-xInxS2 with x=0.14±0.01 was found to be 90° phase-matchable for type-I difference-frequency generation (DFG) by mixing the dual-wavelength
pulses emitted from an electronically tuned Ti:sapphire laser. Infrared radiation continuously tunable over the range of 4.80–6.98 μm
was generated by independently varying the two wavelengths in the 705–932 nm spectral range, and 4.04 μm radiation by mixing
a Nd:YAG laser with the Ti:sapphire laser. In addition, this material was found to be noncritically phase-matchable for the
second harmonic generation (SHG) of CO2 laser radiation at 10.591 μm at 203 °C. Sellmeier equations that reproduce well these experimental data are presented.
PACS 42.65.-k; 42.65.ky 相似文献