共查询到20条相似文献,搜索用时 78 毫秒
1.
A. Predoi-Cross W. Liu C. Povey A.L. Laraia D.R. Hurtmans 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(9):1065-1079
Using a Fourier transform spectrometer setup we have measured the self-broadened half width, pressure shift, and line asymmetry coefficients for transitions in the 30012←00001 and 30013←00001 vibrational bands of carbon dioxide for four different temperatures. A total of 46 pure CO2 spectra were recorded at 0.008 and 0.009 cm−1 resolution and at pressures varying from a few Torr to nearly an atmosphere. The individual spectral line profiles have been fitted by a Voigt profile and a speed-dependent Voigt profile, to which we have added dispersion profiles to account for weak line mixing. A comparison of the sets of results obtained for each band showed no vibrational dependence of the broadening coefficients. The self-broadening and self-shift coefficients are compared to semiclassical calculations based on the Robert-Bonamy formalism and were found to be in good agreement. The line asymmetry results are compared to line mixing calculations based on the Energy Corrected Sudden (ECS) and Exponential Power Gap models. 相似文献
2.
A. Predoi-Cross A.V. Unni I. Schofield A.R.W. McKellar 《Journal of Molecular Spectroscopy》2007,245(1):34-51
Transitions of pure carbon dioxide have been measured using a Fourier transform spectrometer in the 30012 ← 00001 and 30013 ← 00001 vibrational bands. The room temperature spectra, recorded at a resolution of 0.008 cm−1, were analyzed using the Voigt model and a Speed Dependent Voigt line shape model that includes a pressure dependent narrowing parameter. Intensities, self-induced pressure broadening, shifts, and weak line mixing coefficients are determined. The results obtained are consistent with other studies in addition to the theoretically calculated values. Exponential Power Gap (EPG) and Energy Corrected Sudden (ECS) scaling laws were used to calculate the relaxation matrix elements. 相似文献
3.
V. Malathy Devi D. Chris Benner A. Predoi-Cross 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(16):2355-2369
The McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory (NSO) on Kitt Peak, Arizona, was used to record infrared high resolution absorption spectra of CO2 spectra broadened by O2. These spectra were analyzed to measure O2-broadened half-width coefficients, O2-induced pressure-shift coefficients and speed dependent parameters for transitions in the 30013←00001 and 30012←00001 bands of 16O12C16O located near 6227 and 6348 cm−1, respectively. All spectra were obtained at room temperature using the long path, 6 m base path White cell available at NSO. A multispectrum nonlinear least-squares fitting algorithm employing Voigt line shapes modified to include line mixing and speed dependence was used to fit simultaneously a total of 19 spectra in the 6120-6280 cm−1 (30013←00001) and 6280-6395 cm−1 (30012←00001) spectral regions. 16 of the 19 spectra analyzed in this work were self broadened and three spectra were lean mixtures of CO2 in O2. The volume mixing ratios of CO2 in the three spectra varied between 0.06 and 0.1. Lorentz half-width and pressure-induced shift coefficients were measured for all transitions in the P(50)-R(50) range in both vibrational bands. The results obtained from present analysis have been compared with measurements available in the literature for self-, air-, oxygen- and argon-broadening. No significant differences were observed between the broadening and shift coefficients of the two bands. The N2-broadened half-width and pressure-shift coefficients were computed from measured air- and O2-broadened width and shift coefficients. 相似文献
4.
J.S. Li K. Liu W.D. Chen 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(9):1575-1585
Pressure-induced foreign-broadening lineshape parameters of the carbon dioxide rovibrational transitions belonging to the (30012)←(00001) overtone band near the 1.573 μm wavelength region are measured by using a tunable diode laser photoacoustic spectrometer. The spectroscopic analysis has concerned the first 11 lines of the R branch. For these lines, the air- and Ar-broadening coefficients are measured at room temperature (∼298 K). The measured broadening coefficients of all the transitions of 12C16O2 are compared with those given in the HITRAN04 database and former measurements with a different spectroscopic method. Agreements and discrepancies are underlined and briefly discussed. The recorded lineshapes are fitted with standard Voigt line profiles in order to determine the collisional broadening coefficient of carbon dioxide transitions. 相似文献
5.
Previously we obtained self-broadened halfwidth and self-induced shift coefficients at room temperature for 15 near infrared CO2 bands between 4750 and 7000 cm−1 [R.A. Toth, L.R. Brown, C.E. Miller, V.M. Devi, D.C. Benner, J. Mol. Spectrosc., 239 (2006) 243-271]. The present study expands our work on the near infrared line parameters of CO2 to include air broadening coefficients. Here we report nearly 400 air-broadened half width and air-induced pressure shift coefficients spanning 11 different CO2 vibrational bands in the 4750-7000 cm−1 region. Retrievals have been performed using Voigt line profiles over three distinct spectral intervals: (a) 4750-5200 cm−1, covering the 20011 ← 00001, 20012 ← 00001, and 20013 ← 00001 Fermi Triad and three associated hot bands 21111 ← 01101, 21112 ← 01101, 21113 ← 01101; (b) 6100-7000 cm−1, covering the 30011 ← 00001, 30012 ← 00001, 30013 ← 00001 and 30014 ← 00001 Fermi Tetrad; (c) near 6950 cm−1 for the 00031 ← 00001 overtone band. The air-broadened halfwidth and air-induced pressure shift coefficients have been modeled with empirical expressions and compared to other measurements available in the literature. 相似文献
6.
G.D. Roston Z.F. Ghatass 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(18):2174-2179
The collision broadening and shift of the Hg intercombination spectral line 253.7 nm (61S0–63P1) perturbed by Kr has been investigated using a high-resolution scanning Fabry–Perot interferometer. The values of the pressure broadening and shift coefficients β and δ, respectively, for the studied line have been obtained. The obtained coefficients β and δ are compared with their corresponding published experimental values and also those calculated using Lindholm–Foley impact theory. 相似文献
7.
A. Predoi-Cross W. Liu A.V. Unni A.R.W. McKellar 《Journal of Molecular Spectroscopy》2007,246(1):98-112
In this work we present a line profile study for air-broadened carbon dioxide transitions in the 30012 ← 00001 and 30013 ← 00001 vibrational bands. The room temperature spectra were recorded at a resolution of 0.008 cm−1 using a Fourier Transform spectrometer. The air-broadening, air-shift, and air-line mixing coefficients were derived from a simultaneous fitting of spectra using the Voigt model and a Speed-Dependent Voigt lineshape model. The results obtained are consistent with other studies in addition to the theoretically calculated values. Exponential Power Gap (EPG) and Energy Corrected Sudden (ECS) scaling laws were used to calculate the relaxation matrix elements. 相似文献
8.
Line position, intensity and line shape parameters (Lorentz widths, pressure shifts, line mixing, speed dependence) are reported for transitions of the 30013 ← 00001 band of 16O12C16O (ν0 = 6227.9 cm−1). The results are determined from 26 high-resolution, high signal-to-noise ratio spectra recorded at room temperature with the McMath-Pierce Fourier transform spectrometer. To minimize the systematic errors of the retrieved parameters, we constrained the multispectrum nonlinear least squares retrieval technique to use quantum mechanical expressions for the rovibrational energies and intensities rather than retrieving the individual positions and intensities line by line. Self- and air-broadened Lorentz width and pressure-induced shift, speed dependence and line mixing (off-diagonal relaxation matrix elements) coefficients were adjusted individually. Errors were further reduced by simultaneously fitting the interfering absorptions from the weak 30012 ← 00001 band of 16O13C16O as well as the weak hot bands 31113 ← 01101, 32213 ← 02201, 40014 ← 10002 and 40013 ← 10001 of 16O12C16O in this spectral window. This study complements our previous work on line mixing and speed dependence in the 30012 ← 00001 band (ν0 = 6347.8 cm−1) [V.M. Devi, D.C. Benner, L.R. Brown, C.E. Miller, R.A. Toth, J. Mol. Spectrosc. 242 (2007) 90-117] and provides key data needed to improve atmospheric remote sensing of CO2. 相似文献
9.
The pressure broadening, pressure shift coefficients, and absolute intensities have been obtained for theJ= 6 ← 5 and theJ= 5 ← 4 absorption lines of acetonitrile CH3CN at 110 and 92 GHz, respectively. The absorption line shapes have been directly recorded modulating the radiation beam by an optical chopper. In addition to the self-effects, the foreign-broadening coefficients have also been measured for N2, O2, and Ar. 相似文献
10.
Hideo Sagawa Jana Mendrok Takamasa Seta Hiromichi Hoshina Philippe Baron Kodai Suzuki Iwao Hosako Chiko Otani Paul Hartogh Yasuko Kasai 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(18):2027-2036
Carbon dioxide (CO2) induced pressure broadening coefficients of water vapor (H2O) lines have been determined using a terahertz time-domain spectrometer (TDS). Thirty-two rotational transitions of H2O were observed in the spectral range of 18– (550–3050 GHz) for the first time. Using TDS allows one to measure absorption spectra with one order of magnitude better precision than Fourier transform spectrometer in this frequency region. The precision of our broadening coefficient measurements was 2.4% in average. The measured CO2 induced pressure broadening coefficients are compared to those calculated by the complex Robert–Bonamy formalism. The difference between the measurement and the theoretical estimation was in the range of -10.7% to +19.0% confirming the credibility of the theoretical approach. The impact on retrieval of water vapor abundance was examined by performing inversion analysis on H2O spectra of Venus atmosphere obtained with the Submillimeter Wave Astronomy Satellite. In this example case, the retrieved water vapor mixing ratio reduces by half at the altitude region of 70–85 km when applying the newly measured broadening coefficient compared to the air-broadening coefficient, and changes by 5% compared to that estimated by the complex Robert–Bonamy formalism. 相似文献
11.
Using a high-resolution tunable diode laser photoacoustic spectrometer, self-, N2 and O2 pressure broadening coefficients for the first 11 transitions of 12C16O2 in the R branch of the (30012) ← (00001) overtone band at the 6348 cm−1 have been revisited at room temperature (∼298 K). Air-broadening parameters have also been calculated from the N2 and O2 measurements. The dependence of the broadening on rotational quantum number m is discussed. The recorded lineshapes are fitted with standard Voigt line profiles in order to determine the collisional broadening coefficients of carbon dioxide transitions. The results are compared to our previous measurements and to the values reported in the HITRAN04 database and by other research group with a different spectroscopic technique. 相似文献
12.
O.S. Gulidova 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(15):2315-2320
The absorption spectra of carbon dioxide (isotope 626, natural abundance in air, ambient temperature) have been studied at total pressures 68-570 Torr with spectral resolution 0.003-0.005 cm−1. The spectra were measured in the spectral domain of 2273-2393 cm−1 by FTIR spectrometer Bruker IFS 125 HR equipped with White-type multipass cell (6.4-41.6 m) and with a cell having 10 cm optical path length. Pressure broadening and shift coefficients were obtained from a series of spectra by means of a nonlinear least-squares spectral fitting technique for the lines of the (00011)←(00001) band with rotational quantum number up to J=82. For fitting of the individual line shapes, we used the Voigt profile with pre-calculated Doppler broadening parameter. The experimental pressure broadening and shift coefficients are compared with the values available in spectroscopic databases HITRAN 2008 and Carbon Dioxide Spectroscopic Databank (CDSD-296) and with other experimental values reported in the literature. 相似文献
13.
Ayan Ray Amitava Bandyopadhyay Sankar De Biswajit Ray Pradip N. Ghosh 《Optics & Laser Technology》2007,39(2):359-367
A very simple and inexpensive tunable semiconductor diode laser controller is designed for stable operation of the diode laser. The diode laser controller is stable within +/−8 μA and +/−10 mK, respectively. The noise spectrum of the current controller is studied by FFT analysis. We have used our home-made diode laser system in a tunable diode laser absorption spectrometer (TDLAS) to probe weak overtone transitions of water vapour molecule. The diode laser wavelength is coarsely tuned by changing the operating temperature to probe (2, 1, 1)←(0, 0, 0) band overtone transitions of water vapour within 818–835 nm. To demonstrate line shape study, seven transitions are scanned by ramping the drive current of the diode laser (at constant operating temperature) under different perturber (laboratory air) pressures within the sample cell. A balanced detector and a lock-in amplifier are used for phase sensitive detection purpose. Small current modulation amplitude, balanced detection and proper adjustment of the lock-in amplifier help to obtain a S/N ratio ranging from 100 to 7 using a small sample path length of 1.5 m. Experimentally obtained derivative spectrum is numerically integrated to reveal the original line shape and fitted with a nonlinear least squares fitting program to extract air broadening coefficients and line strength parameters. The spectroscopic line parameters are compared with the results from HITRAN database. 相似文献
14.
H. Aroui H. Laribi J. Orphal P. Chelin 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(18):2037-2059
Using Fourier-transform spectra (Bruker IFS 120 HR, resolution ≈0.004 cm−1) of NH3 in nine branches of the ν2, 2ν2 and ν4 bands, self-broadening and self-shift as well as self-mixing coefficients have been determined at room temperature (T=295 K) for more than 350 rovibrational lines located in the spectral range 1000–1800 cm−1. A non-linear least-squares multispectrum fitting procedure, including line mixing effects, has been used to retrieve successively the line parameters from 11 experimental spectra recorded at different pressures of pure NH3. The accuracies of self-broadening coefficients are estimated to be better than 2% for most lines. The mean accuracies of line-mixing and line-shift data are estimated to be about 15% and 25%, respectively. The results are compared with previous measurements and with values calculated using a semiclassical model based upon the Robert–Bonamy formalism that reproduces rather well the systematic experimental J and K quantum number dependencies of the self-broadening coefficients.The results concerning line mixing demonstrate a large amount of coupling between the symmetric and asymmetric components of inversion doublets mainly in the ν4 band. The line mixing parameters are both positive and negative. More than two thirds of the lines studied here have a positive shift coefficient. However, for most of them the shift coefficients are negative in the 2ν2 band. They are positive for the R branch of the ν2 band and for the PR and RP branches of the ν4 band. For the other branches they are both positive and negative. Some components of inversion doublets illustrate a correlation between line mixing and shift phenomena demonstrated by a quadratic pressure dependence of line position. 相似文献
15.
M.A.H. Smith D. Chris Benner V. Malathy Devi 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(9):1152-1166
Accurate values for line positions, absolute line intensities, self-broadened half width and self-pressure-induced shift coefficients have been measured for over 400 allowed and forbidden transitions in the ν4 band of methane (12CH4). Temperature dependences of half width and pressure-induced shift coefficients were also determined for many of these transitions. The spectra used in this study were recorded at temperatures between 210 and 314 K using the National Solar Observatory's 1 m Fourier transform spectrometer at the McMath-Pierce solar telescope. The complete data set included 60 high-resolution (0.006-0.01 cm−1) absorption spectra of pure methane and methane mixed with dry air. The analysis was performed using a multispectrum nonlinear least squares curve fitting technique where a number of spectra (20 or more) were fit simultaneously in spectral intervals 5-15 cm−1 wide. In addition to the line broadening and shift parameters, line mixing coefficients (using the off-diagonal relaxation matrix element formalism) were determined for more than 50 A-, E-, and F-species transition pairs in J manifolds of the P- and R-branches. The measured self-broadened half width and self-shift coefficients, their temperature dependences and the line mixing parameters are compared to self-broadening results available in the literature and to air-broadened parameters determined for these transitions from the same set of spectra. 相似文献
16.
《Proceedings of the Combustion Institute》2023,39(1):735-743
We address the role of the linear mixing rule in the kinetics of the H2O2 decomposition system by reporting the rate constant for H2O2 + M = 2OH + M (M = Ar and CO2) in the temperature range of 1087–1234 K at low pressures in a mixture of 20% CO2 in Argon. The reaction rate constant was inferred from H2O concentrations monitored by using a laser-absorption spectroscopy-based water diagnostic. To the best of our knowledge, this is the first measurement of the rate constant of this reaction in a mixture to be reported in literature. A significant discrepancy was found between the rate constants derived using the traditional linear mixing rule and the reduced pressure linear mixing rule. This discrepancy can have serious implications on the predictive accuracy of these kinetic models, especially under conditions relevant to the operation of supercritical CO2 (sCO2) power cycles that rely on oxy-fuel combustion in a working fluid comprised almost entirely of CO2. 相似文献
17.
New sharp bands of formic acid have been observed in the near ultraviolet at the long wave-length end of the previously observed diffuse band system (2250–2500 Å) by considerably extending the absorption path length. Both the diffuse and sharp bands belong to the same vibrational system which is assigned to the π* ← n electronic transition in the carbonyl group. Extensive progressions are observed in the carbonyl stretching frequency which is greatly reduced in the excited state (fundamental ν3′ ≈ 1080 cm−1) and many intervals of about 400 cm−1 are assigned to the OCO bending frequency ν7′.A band contour analysis of the 2593 Å band shows that the molecule is nonplanar in the excited state because of the magnitude and sign of the inertial defect. From this analysis, the rotational constants for the excited state are S‘=1.8755, B‘0.4042, C‘=0.3378cm−1 By the plausible assumption that the important changes in the molecule are in the C=0 bond length, the OCO angle, and the nonplanarity due to the formyl hydrogen, the following excited state parameters are derived.rC=0 = 1.407A.The changes in formic acid are closely analogous to the changes in formyl fluoride as a result of the π* ← n transition. 相似文献
18.
Robert R. Gamache Julien Lamouroux Anne L. Laraia Jean-Michel Hartmann Christian Boulet 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(11):976-990
Calculations of the half-width, its temperature dependence, and the line shift are made for the rotational states J=0–120 for two of the Fermi-tetrad bands (30012←00001 and 30013←00001) of CO2 perturbed by N2. The calculations employ the semi-classical complex Robert–Bonamy method with no ad hoc scaling, J-dependent or otherwise, and an intermolecular potential (IP) comprised of an electrostatic part, an atom–atom part, and an isotropic London dispersion part. The averaging over the impact parameter b and relative speed v are explicitly carried out. Many interesting features about CO2 as the radiating molecule are elucidated. Effects of the trajectory model, the order of the expansion of the atom–atom component of the potential, and the inclusion of the imaginary terms are studied. It is shown that the results are very sensitive to the intermolecular potential. The final IP parameters give results that demonstrate excellent agreement with measurement for the three line shape parameters studied in this work. 相似文献
19.
M. Sanzharov J. Vander Auwera O. Pirali P. Roy J.-B. Brubach L. Manceron T. Gabard V. Boudon 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(15):1874-1886
Following our recent study devoted to measurements of intensities of pure rotation lines of methane, room temperature far infrared spectra of methane diluted in nitrogen at five total pressures between 100 and 800 hPa have been recorded at the AILES beamline of the SOLEIL synchrotron. One hundred and five N2 broadening coefficients of methane pure rotation lines have been measured in the 83–261 cm?1 spectral range using multi-spectrum non-linear least squares fitting of Voigt profiles. Pressure-induced line shifts were not needed to fit the spectra to the noise level and line mixing effects were neglected. One hundred and seventy-six self broadening coefficients have also been measured in the 59–288 cm?1 spectral range using the pure methane spectra recorded in our previous work. The measured N2 broadening coefficients were compared to semi-classical calculations. 相似文献
20.
A semi-empiric approach to the calculation of spectral line half-widths and shifts is proposed. This approach is based on the Anderson approximation and includes the correction factors, the parameters of which can be determined by fitting the broadening or shifting coefficients to the experimental data. This allows sufficiently accurate predictions of the parameters of line profiles that were not measured. The coefficients of CO2 and H2O spectral line broadening and shifting due to air and nitrogen pressure are calculated, as well as the coefficients of their temperature dependence. The calculated coefficients agree satisfactorily with measured values. 相似文献