共查询到20条相似文献,搜索用时 31 毫秒
1.
N.N. Lavrentieva A.M. Solodov A.A. Solodov 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(15):2291-26067
The water vapor line broadening and shifting in the ν1+ν2+ν3 band induced by nitrogen pressure are measured with Bruker IFS 125 HR FTIR spectrometer at the spectral resolution of 0.01 cm−1 for the line with upper states angular momentum up to 11. Line contour parameters are calculated using a semi-empirical approach extended by the use of empirical data to determine some fitting model parameters. We use the complete set of high accuracy vibration-rotation dipole transition moments calculated for all possible transitions using wavefunctions determined from variational nuclear motion calculations and an ab initio dipole moment surface. Calculated values of line contour parameters are in a good agreement with observed parameters. 相似文献
2.
T.M. Petrova A.M. Solodov A.A. Solodov A.S. Dudaryonok N.N. Lavrentieva 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(18):2741-2749
Oxygen pressure induced broadening and shifting coefficients for water vapor absorption lines in the 8600–9010 cm−1 region have been measured and calculated. The spectra were recorded with a Bruker IFS 125HR spectrometer at a spectral resolution of 0.01 cm−1 for lines with angular moment of the upper states up to 10. Calculations of line broadening and shifting coefficients are performed using a semi-empirical approach. The method is based on the impact theory of broadening, and includes the correction factors whose parameters can be determined by fitting the broadening or shifting coefficients to the experimental data. The comparison of our calculations with the experimental values argues that the semi-empirical method is quite acceptable for the determination of the water vapor absorption line profile parameters. 相似文献
3.
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
4.
T. M. Petrova A. M. Solodov A. A. Solodov V. M. Deichuli V. I. Starikov 《Molecular physics》2018,116(10):1409-1420
The water vapour line broadening and shifting for 97 lines in the ν1 + ν2 + ν3 band induced by hydrogen pressure are measured with Bruker IFS 125 HR FTIR spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm?1 and in a wide pressure range of H2. The calculations of the broadening γ and shift δ coefficients were performed in the semi-classical method framework with use of an effective vibrationally depended interaction potential. Two potential parameters were optimised to improve the quality of calculations. Good agreements with measured broadening coefficients were achieved. The comparison of calculated broadening coefficients γ with the previous measurements is discussed. The analytical expressions that reproduce these coefficients for rotational, ν2, ν1, and ν3 vibrational bands are presented. 相似文献
5.
The linestrengths, self-pressure broadening and shifting coefficients have been measured for P3 (10)- R3 (12) lines in the second overtone band of hydrogen iodide. A dipole moment function in terms of the reduced nuclear displacement x = (R − Re)/Re is obtained using rotationless dipole matrix elements determined by the Herman-Wallis analysis of the (1, 2, 3 ← 0) HI bands: μ (x) = 0.4471(5) − 0.0770(2)x + 0.547(3)x2 − 1.93(2)x3, in a full agreement with the function proposed previously [J. Mol. Spectrosc. 223 (2004) 67]. A close match is demonstrated of the results of most recent relativistic calculations [Phys. Chem. Chem. Phys. 6 (2004) 3779] with the spectroscopically derived electric dipole parameters for HI. Line-mixing in the band head is observed, the self-pressure shifting and broadening coefficients for the (3 ← 0) band lines are determined. 相似文献
6.
The potential energy curve and theoretical dipole moment function of the a4Π state of NO have been determined using full-valence and first-order configuration interaction wavefunctions. Using these two different wavefunctions, the dipole moments of the a4Π, v = 3 level have been found equal, respectively, to 0.16 D and 0.30 D, with the polarity N+O?. These values compare well with the value of |0.20 ± 0.04| D determined by Lisy and Klemperer. The first derivative of the dipole moment has also been calculated to be equal to 1.25–1.73 D/bohr. 相似文献
7.
The pressure-induced shifting coefficients and line mixing parameters have been studied in the ν4 band of NH3 perturbed by CO2 and He at room temperature. Measurements have been made using a high-resolution Fourier transform spectrometer. The measurements cover the PP and RP branches of the ν4 band and are located in the spectral range 1470-1600 cm−1. The line shift and line mixing parameters have been derived from a non-linear least-squares multi-pressure fitting technique. The shift coefficients are compared to a semiclassical calculation based on the Robert-Bonamy formalism employing two types of intermolecular interactions. It is shown that the line shifts mainly originate from the vibrational dephasing effects. The observed interference parameters are compared with calculations based on state-to-state collisional cross sections calculated from the intermolecular potential with a semiclassical approach. The results of computation are in reasonable agreement with the experimental data. It is demonstrated also that the line mixing process mainly originates from the energy transfer between symmetric and antisymmetric components of the inversion doublets. 相似文献
8.
Gang Li Jeremy J. Harrison Ram S. Ram Colin M. Western Peter F. Bernath 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(1):67-74
Einstein A coefficients and absolute line intensities have been calculated for the E2Π–X2Σ+ transition of CaH. Using wavefunctions derived from the Rydberg–Klein–Rees (RKR) method and electronic transition dipole moment functions obtained from high-level ab initio calculations, rotationless transition dipole moment matrix elements have been calculated for all 10 bands involving v′=0,1 of the E2Π state and v″=0,1,2,3,4 of the X2Σ state. The rotational line strength factors (Hönl–London factors) are derived for the intermediate coupling case between Hund's case (a) and (b) for the E2Π–X2Σ+ transition. The computed transition dipole moments and the spectroscopic constants from a recent study [Ram et al., Journal of Molecular Spectroscopy 2011;266:86–91] have been combined to generate line lists containing Einstein A coefficients and absolute line intensities for 10 bands of the E2Π–X2Σ+ transition of CaH for J-values up to 50.5. The absolute line intensities have been used to determine a rotational temperature of 778±3 °C for the CaH sample in the recent study. 相似文献
9.
J.T. Hodges D. Lisak N. Lavrentieva L. Sinitsa R.J. Barber 《Journal of Molecular Spectroscopy》2008,249(2):86-94
We report N2 and air foreign pressure broadening coefficients of more than twenty rovibrational transitions of water vapor in the 935-nm spectral region, and these measurements are compared to new theoretical calculations. The data were obtained using the frequency-stabilized cavity ring-down spectroscopy method, yielding relative uncertainties for the broadening parameters in the range 0.4-2.2%. The sensitivity of measured broadening parameters to the choice of line shape functions is discussed, and systematic differences between experimentally determined collisional broadening coefficients are shown for the cases when the observed line narrowing is interpreted in terms of Dicke-narrowing or the speed-dependence of the collisional broadening and shifting. Theoretical models of pressure broadening for these transitions agree with the measurements to within 4% for most transitions with an average relative difference of 0.63%. 相似文献
10.
H. Tran J.-L. Domenech R.R. Gamache 《Journal of Quantitative Spectroscopy & Radiative Transfer》2007,108(1):126-145
This paper is devoted to the effects of velocity on the shapes of six R(J) lines of the ν3 band of water vapor diluted in N2. The experiments have been made at room temperature for total pressures between 0.1 and 1.2 atm using a tunable infrared laser frequency difference spectrometer. These measurements, which study broad and narrow lines of low and high J values, are first analyzed using the Voigt and the hard collision (HC) model. It is shown that both lead to unsatisfactory results, the Voigt profile being unable to account for the line narrowing whereas the friction (narrowing) parameter deduced using the HC approach has an unphysical dependence on pressure. Furthermore, at elevated pressure where Dicke narrowing and Doppler effects are negligible, deviations between experimental and fitted profiles are still observed, indicating inhomogeneous effects due to the speed dependence of collisional parameters. In order to go further, an approach based on the kinetic impact equation accounting for both the Dicke narrowing and the speed dependence has been applied. It uses velocity-dependent broadening and shifting coefficients calculated with a semi-classical approach and two parameters. The latter, which govern the memory functions of the modulus and orientation of the H2O velocity are considered as free parameters and determined from experiments. The results show that all profiles, regardless of pressure and of the transition, can be correctly modeled using a single set of memory parameters. This demonstrates the consistency of the approach, which is then used to analyze the different regimes that monitor velocity effects on the line profile. 相似文献
11.
J.-Y. Mandin J.-M. Flaud C. Camy-Peyret G. Guelachvili 《Journal of Quantitative Spectroscopy & Radiative Transfer》1980,23(4):351-370
The self-broadening coefficients of 150 lines belonging to the v2 band of H216O between 1770 and 2250 cm-1 have been measured using Fourier transform spectra (resolution ≈ 0.005 cm-1). The four different methods which have been used to deduce the self-broadening coefficients from experiment are described in detail. The estimated average uncertainty is about 15% and varies from 7 to 30%, depending on the method used and on the line involved. Two theoretical calculations, one based on the Anderson-Tsao-Curnutte method and the other on the recent method proposed by Davies, have been performed, retaining only the dipole-dipole interaction. For some lines of the v2 band and for some pure rotation lines, calculations based on other formalisms have also been performed. For all of these calculations, we have used accurate spectroscopic data: precise energy levels, realistic wavefunctions, and a complete dipole-moment operator expansion in order to compute the transition probabilities. As compared to the previously calculated values of the pioneering work of Benedict and Kaplan, where the Anderson-Tsao-Curnutte method was used, our calculations show improvements by about 14% in the agreement between measured and calculated self-broadening coefficients. 相似文献
12.
Anuradha Natarajan L. Natarajan 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(12-13):2281-2290
Relativistic calculations on the energies and electric dipole rates of Kβ X-rays from 1s3p(1P1,3P1)-1s2 (1S0) transitions for He-like ions in the range Z=14–54 are carried out using multi-configuration Dirac–Fock (MCDF) wave functions in the active space interaction approach. The contributions from Breit interaction and quantum electrodynamics have also been included in the calculation. An attempt has been made to find a scaling expression for Breit energy in terms of Zα .The scaled Breit energies are in good agreement with the earlier accurate relativistic results and this ensures the reliability of our scaling procedure. The behavior of MCDF wavefunctions for a given J in the non-relativistic limit has also been studied. The calculated Kβ X-ray energies and rates agree well with other available experimental and theoretical values. 相似文献
13.
We calculate vibronic transition moments for the A?2A1-X?2, electronic band system, and for the vibrational transitions within the à and [Xtilde] states, of the NH2 free radical with the purpose of assisting in the quantitative interpretation of cometary NH2 emission spectra. To do this it is necessary to use molecular wavefunctions, and electric dipole moment and transition moment surfaces. The wavefunctions are obtained using our program system RENNER after we have determined optimized à and [Xtilde] state potential energy surfaces in a fitting to data. We have obtained the electric dipole moment and transition moment surfaces by ab initio calculation. 相似文献
14.
W. F. Mahmoudi N. Ben Nessib S. Sahal-Bréchot 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):7-10
Owing to the increasing sensitivity of detectors,
accurate line profiles are needed for accurate stellar
atmospheres modelling and for laboratory and technological plasmas
as well. So, Stark broadening parameters of isolated lines of
complex atoms and ions within the impact and quasistatic
approximation are needed, even if the atomic abundance of the considered element is low.
Angular factors of the diagonal line strength entering the
quadrupole term appearing in the semi-classical expression of the
width of line broadened by electron or ion perturbers, are needed.
The aim of this paper is to extend the previous calculations of
this diagonal multiplet factor which were obtained for
configurations of the type ln and l1
nl2
m to
more complex configurations in LS coupling.
To study the Stark broadening of isolated lines in the impact and
quasistatic approximation, we use the semi-classical-perturbation
treatment, including both dipole and quadrupole contribution in
the expansion of the electrostatic interaction between the optical
electron and the perturber. We also use the Fano-Racah algebra.
Angular factors of the diagonal line strength entering the
quadrupole term appearing in the semi-classical expression of the
width of line broadened by electron or ion perturbers, are
calculated. New diagonal multiplet factor formulae for more
complicated configurations such as
(n1l1
n(LnSn)n2l2
m(LmSm)n3l3
p(LpSp))
are provided.
These formulae can enter the computer Stark semi-classical
perturbation codes. 相似文献
15.
H. Tran J.-M. Hartmann L.R. Brown T. Warneke F. Hase 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(10):1344-2112
This paper presents a study of absorption in N2-broadened P and R manifolds of the 2ν3 band of CH4 near 6000 cm−1 using high resolution laboratory and atmospheric spectra. This region is of prime importance for the retrieval of methane abundances in the Earth's atmosphere using ground-based or space-borne spectrometers. Recent laboratory investigations have been devoted to the methane spectroscopic parameters in this band, motivated by their previous poor knowledge and their increasing use by remote sensing experiments. In the absence of a better model, previous studies have used Voigt line shapes and thus purposely neglected line mixing (LM). In this paper, we first present direct comparisons between measured laboratory spectra and the results of a model which accounts for LM without adjusting any of the spectroscopic parameters. A good agreement is obtained and the results show that LM does have a significant influence on the shapes of P and R manifolds. Hence, most previously observed discrepancies were not due to improper broadening and shifting coefficients but to the neglect of this effect. This also confirms that widths and shifts derived in recent 2ν3 band studies neglecting LM are “effective” and lack physical meaning, as suggested in a previous work [17] (Frankenberg et al., 2008). In a second step, the conclusions from the laboratory data are tested using ground-based atmospheric solar absorption spectra. The fit residuals obtained confirm the quality of the proposed model and evidence the impact of line mixing on CH4 atmospheric spectra. The present results also confirm that laboratory and atmospheric spectra can alternatively be accurately modeled neglecting LM and using ad hoc broadening and shifting parameters. Conclusions of this exercise can be drawn from two perspectives. From the point of view of spectroscopy and understanding of processes, accurate line parameters will not be deduced from fits of laboratory measurements unless line-mixing effects are included in the spectral-shape model. In the meantime, and from the point of view of atmospheric retrievals, neglecting LM with suitable effective line parameters is convenient and accurate (within current retrieval uncertainties). Note that this is only true if this approach is not used for total pressures significantly above 1 atm (e.g. Jupiter). 相似文献
16.
F. Thibault K.A. Grabow C.I. Marcus L.A. Robertson M.C. Stoffel 《Journal of Molecular Spectroscopy》2009,256(1):17-2081
Theoretical and experimental values have been determined for the pressure broadening of the ν1 + ν3 band of acetylene by hydrogen and deuterium at 195 K, and experimental values of the pressure shifts have been determined. Theoretical values have been calculated on the basis of a recent potential energy surface using the close coupling scheme. We discuss the detailed contribution of the various rotational angular momenta of the perturbing gas and the ortho and para contribution to the total pressure broadening cross-sections. We give routes to circumvent the computational cost of such calculations. Experimental values have been measured using a tunable diode laser spectrometer assuming a Voigt line shape. These pressure broadening parameters are compared with measurements performed recently at room temperature and with present measurements performed at 195 K in the ν1 + ν3 band of acetylene. A satisfactory agreement is obtained with the present results and available ones at 295 K. 相似文献
17.
K.S. Bond N.D. Collett E.P. Fuller J.L. Hardwick E.E. Hinds T.W. Keiber I.S.G. Kelly-Morgan C.M. Matthys M.J. Pilkenton K.W. Sinclair A.A. Taylor 《Applied physics. B, Lasers and optics》2008,90(2):255-262
Pressure broadening and shift coefficients for the ν1+ν3 band of 12C2H2 have been measured for He, Ne, and Ar at a temperature of 195 K using high resolution diode laser spectroscopy. The pressure
broadening and shifts follow patterns with rotational assignment that are similar to those at room temperature but are generally
larger in magnitude. The change in magnitude is qualitatively described by assuming, for each transition, a constant cross
section for pressure broadening or shifting. Better agreement may be obtained for pressure broadening coefficients by using
empirically determined temperature exponents; better agreement still is obtained from close coupling calculations of the pressure
broadening cross sections.
PACS 33.70.Jg 相似文献
18.
A.W. Mantz F. Thibault B. Fernandez H. Koch C. Claveau D. Hurtmans 《Journal of Molecular Spectroscopy》2003,222(2):131-141
We present measurements of Ar-broadening parameters for the R(0) and R(7) lines in the fundamental band of 13CO at eight temperatures from 80 to 297 K. The broadening parameters are determined by simultaneous least-squares fitting of spectra recorded using a frequency stabilized diode laser spectrometer. The comparison of the broadening parameter values for R(7) derived at room temperature and different pressures from different line profiles shows that an empirical line profile, which takes into account narrowing effects (Dicke narrowing and absorber speed dependence) but neglects any correlation between collisions, is able to describe the observed lines with constant values of the narrowing and broadening parameters over a 10-500 Torr pressure range. Starting from a recent ab initio potential energy surface, theoretical thermally averaged close coupling values of the Ar broadening parameter are calculated for the same temperatures. The comparison between experimental and calculated values shows an overall agreement of 1.5%. 相似文献
19.
The coefficients of the water vapor line shifts induced by the pressure of oxygen, nitrogen, and argon are measured and calculated in the spectral range from 5000 to 5600 cm?1. The experimental data are obtained from the analysis of the absorption spectra of H2O-O2, H2O-N2, and H2O-Ar mixtures measured on a Fourier spectrometer with a resolution of 0.007 cm?1 in a wide pressure range of buffer gases at room temperature for an optical path length of 84.05 m. The calculations are performed according to the Anderson impact theory of broadening with the use of only one adjustable parameter—the effective mean dipole polarizability of the upper vibrational state. The shifts of one and the same lines induced by the pressure of different buffer gases are compared; the role played by different terms of the intermolecular potential in the formation of the shifts is analyzed. 相似文献
20.
Jean-Marcel Colmont François Rohart Georges Wlodarczak 《Journal of Molecular Spectroscopy》2007,241(2):119-123
We report on experimental collisional relaxation of the J = 24 ← 23 line of HC314N, located near 218.3 GHz, induced by nitrogen, hydrogen, and helium. The measurements were carried out at selected temperatures in the 235-350 K range using a video-type spectrometer. The foreign gas broadening parameters and their temperature dependences were determined assuming Voigt lineshape profiles and the usual T−n temperature law. The experimental broadening parameters are compared with results derived using the ATC collisional formalism. 相似文献