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The infrared spectrum of cyanoacetylene (also called propynenitrile) has been investigated from 400 to 4000 cm−1 at a resolution of 0.5 cm−1. Integrated intensities of the main bands and a number of weaker bands have been obtained with an uncertainty better than 5%. Inaccurate values in previous studies have been identified in particular concerning the intensity of the strong ν5 stretching band at 663.2 cm−1. Former results on the temperature dependence of integrated intensities have also been revisited.Synthetic spectra calculation has been performed for the ν5 and ν6 bands on the basis of the best available high resolution data. It has been shown that the GEISA line parameters for HC3N are not sufficient to reproduce the band intensities and some hot band features observed in our experimental spectra at room temperature. As a first step, the model spectra has been improved by including a number of missing hot subbands and by calculating accurately the hot band relative intensities. Finally, a perfect agreement between calculated and observed spectra was achieved on the basis of a global analysis of HC3N levels up to 2000 cm−1 combined with the new integrated intensity measurements. A new extensive line list for the ν5 and ν6 bending modes of HC3N has been compiled. 相似文献
3.
B.V. Perevalov A. Campargue B. Gao S. Kassi V.I. Perevalov 《Journal of Molecular Spectroscopy》2008,252(2):190-197
Line intensities of 12C16O2 transitions have been measured by CW-Cavity Ring Down Spectroscopy in four wavenumber intervals near 1.6 μm. Intensity values of 952 transitions ranging from 1.10 × 10−28 to 4.94 × 10−25 cm/molecule were retrieved with an average accuracy of 4%. These transitions belong to a total of 30 bands corresponding to the ΔP = 9 series of transitions. The achieved sensitivity (noise equivalent absorption αmin ∼ 3 × 10−10 cm−1) allows lowering by more than two orders of magnitude the lower intensity values measured in the region. Comparison with the values included in the JPL database [R.A. Toth, L.R. Brown, C.E. Miller, V. Malathi Devi, D.C. Benner, J. Quant. Spectrosc. Radiat. Transf. 109 (2008) 906-921] shows residuals exceeding one order of magnitude for weak lines. The measured intensities together with a selection of experimental intensities available in the literature were used to extend and refine the set of effective dipole moment parameters for the ΔP = 9 series of transitions of the principal isotopologue of carbon dioxide. The refined parameters allow reproducing, within the experimental uncertainties, the whole set of intensity measurements which extends over nearly six orders of magnitude (1.10 × 10−28-6.12 × 10−23 cm/molecule). Combining the CW-CRDS line positions with the calculated line intensities, a line list has been generated for the whole 5851-7045 cm−1 region and is provided as Supplementary Material. The obtained effective dipole moment parameters have also been used to generate the ΔP = 9 series of transitions included in the new version of the CDSD database. The comparison of the CDSD line intensities with the values provided by the HITRAN-2004 database shows discrepancies up to 80% for some of the bands while discrepancies up to three orders of magnitude are noted for the weakest bands included in the JPL database. 相似文献
4.
B.V. Perevalov T. Deleporte S. Kassi J. Vander Auwera V.I. Perevalov 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(11):2009-2026
Line intensities of 13C16O2 have been measured between 5851 and 6580 cm−1 using CW-cavity ring down spectroscopy (CRDS) and in the 4700-5050 and 6050-6850 cm−1 regions using Fourier transform spectroscopy. As a result of the high sensitivity (noise equivalent absorption αmin∼3×10−10 cm−1) and high dynamics allowed by CW-CRDS, accurate line intensities of 2039 transitions ranging between 1.1×10−28 and 1.3×10−23 cm−1/(molecule cm−2) were measured with an average accuracy of 4%. These transitions belong to a total of 48 bands corresponding to the ΔP=9 series of transitions. Additionally, unapodized absorption spectra of 13C-enriched samples have been recorded using a high-resolution Bruker IFS125HR Fourier transform spectrometer. Spectral resolutions of 0.004 cm−1 (maximum optical path difference (MOPD)=225 cm) and 0.007 cm−1 (MOPD=128.6 cm), and pressure×path length products in the ranges 5.2-12 and 69-450 hPa×m have been used for the lower and higher energy spectral regions, respectively. Absolute line intensities have been measured in the 2001i−00001, 3001i−00001 (i=1, 2, 3) and 00031−00001 bands. An excellent agreement was achieved for the line intensities of the 3001i−00001 (i=1, 2, 3) bands measured by both FTS and CW-CRDS. The CW-CRDS and FTS experimental intensity data together with selected intensity information from the literature have been fitted simultaneously using the effective operators approach. Two sets of effective dipole moment parameters have thus been obtained, which reproduce the observed line intensities in the 2.0 and 1.6 μm regions within experimental uncertainties. 相似文献
5.
The high resolution absorption spectra of 13CH4 were recorded at 81 K by differential absorption spectroscopy using a cryogenic cell and a series of distributed feed back (DFB) diode lasers and at room temperature by Fourier transform spectroscopy. The investigated spectral region corresponds to the high energy part of the 13CH4 tetradecad dominated by the 2ν3 overtone near 5988 cm−1. Empirical line lists were constructed containing, respectively, 1629 13CH4 transitions detected at 81 K (5852-6124 cm−1) and 3481 features (including 85 lines of 12CH4) measured at room temperature (5850-6150 cm−1); the smallest measured intensities are about 3 × 10−26 and 4 × 10−25 cm/molecule at 81 and 296 K, respectively. The lower state energy values were derived for 1196 13CH4 transitions from the variation of the line intensities between 81 and 296 K. These transitions represent 99.2% and 84.6% of the total absorbance in the region, at 81 and 296 K, respectively. Over 400 additional weak features were measured at 81 K and could not be matched to lines observed at room temperature. The quality of the resulting empirical low energy values is demonstrated by the excellent agreement with the already-assigned transitions and the clear propensity of the empirical low J values to be close to integers. The two line lists at 81 and at 296 K provided as Supplementary material will enable future theoretical analyses of the upper 13CH4 tetradecad. 相似文献
6.
The spatial and temporal behavior of the tantalum plasma produced in air by third harmonic Nd:YAG laser (0.6 GW cm−2) has been studied using optical emission spectroscopy. Excitation temperature and electron density have been estimated from the analysis of spectral data as well as their spatio-temporal evolutions. As the delay time increases from 400 to 2000 ns, the excitation temperature has found to decrease from 10,000 K to 7900 K. The value of Ne decreases continuously from 4 × 1018 near the zero position to 5 × 1017 in a linear approach along with the propagation axe of the plasma plume. Laser-supported consumption wave regime has been proposed to explain the propagation of the plasma. 相似文献
7.
The high resolution absorption spectrum of methane has been recorded at liquid nitrogen temperature by direct absorption spectroscopy between 1.62 and 1.71 μm (5852-6181 cm−1) using a newly developed cryogenic cell and a series of distributed feedback (DFB) laser diodes. The minimum value of the measured line intensities is on the order of 3 × 10−26 cm/molecule The investigated spectral range corresponds to the high energy part of the tetradecad dominated by the 2ν3 band for which a theoretical treatment is not yet available. The positions and strengths at 81 K of 2187 transitions were obtained from the spectrum analysis. From the values of the line strength at liquid nitrogen and room temperatures, the low energy values of 845 transitions could be determined. The obtained results are discussed in relation with the previous work of Margolis and compared to the line list provided by the HITRAN database. 相似文献
8.
J.-M. Flaud A. Perrin H. Beckers 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(6):995-1003
The 10 μm region of thioformaldehyde (H2CS) has been recorded at high resolution (0.005 cm−1) using a Fourier transform spectrometer. H2CS was produced by low-pressure pyrolysis of a gas flow of C3H5SCH3 in Ar at 560 °C or CH3SCl at 1150 °C, which was introduced into a multipass White cell with an optical path length of 32 m. Forty scans were recorded for the range 750-1400 cm−1 at a total pressure of 0.15 mbar. A thorough analysis of the three lowest wavenumber fundamental bands, ν3, ν4 and ν6, which fall in this region, has been carried out using a Hamiltonian model, which takes explicitly into account the numerous resonances affecting the ro-vibrational energy levels; especially the massive A-type Coriolis resonance between the out-of-plane wagging mode, ν4, and the in-plane rocking mode, ν6. These two modes are only separated by 0.83 cm−1, and they are thoroughly mixed. From the fittings, the following band centers were derived: νo (ν4)=990.18213(40) cm−1, νo (ν6)=991.02021(50) cm−1 and νo (ν3)=1059.20476 (30) cm−1 where the uncertainties are one standard deviation. In addition, a number of relative line intensities were measured permitting the determination of relative values of the first-order transition moments and therefore relative band intensities for all three bands. Finally, a comprehensive list of line wavenumbers and relative intensities has been generated. 相似文献
9.
Over 8000 line positions and intensities of phosphine (PH3) at 3 μm have been measured at 0.0115 cm−1 resolution with the McMath-Pierce Fourier Transform spectrometer at Kitt Peak. The observed line intensities ranged from 4.13 × 10−6 to 4.69 × 10−2 cm−2 atm−1 at 296 K, for line positions between 2724.477 and 3601.652 cm−1. This region spans eight interacting vibrational states: 3ν2 (2940.8 cm−1), 2ν2 + ν4 (3085.6 cm−1), ν2 + 2ν4 (3214.9 cm−1), ν1 + ν2 (3307.6 cm−1), ν2 + ν3 (3310.5 cm−1), 3ν4 (∼3345 cm−1), ν1 + ν4 (3426.9 cm−1), and ν3 + ν4 (3432.9 cm−1). Assignments have been determined for all the bands except 3ν4 (a weak band in a highly congested area) for a total of 4232 transitions. The total integrated intensity for this region is 5.70 cm−2 atm−1 near 296 K, and assigned lines account for 79% of the observed absorption. The two strongest bands in the region are ν1 + ν4 and ν3 + ν4 with band strengths at 296 K of 1.61 and 2.01 cm−2 atm−1, respectively. An empirical database of PH3 line parameters (positions, intensities, and assignments) is now available. Lower state energies (corresponding to assignments from this study) and line widths from the literature are included; default values are used for unassigned features. 相似文献
10.
This paper presents an analytical and numerical investigation of an intense circularly polarized wave propagating along the static magnetic field parallel to oscillating magnetic field in magnetoactive plasma. In the relativistic regime such a magnetic field is created by pulse itself. The authors have studied different regimes of propagation with relativistic electron mass effect for magnetized plasma. An appropriate expression for dielectric tensor in relativistic magnetoactive plasma has been evaluated under paraxial theory. Two modes of propagation as extraordinary and ordinary exist; because of the relativistic effect, ultra-strong magnetic fields are generated which significantly influence the propagation of laser beam in plasma. The nature of propagation is characterized through the critical-divider curves in the normalized beam width with power plane For given values of normalized density (ωp/ω) and magnetic field (ωc/ω) the regions are namely steady divergence (SD), oscillatory divergence (OD) and self-focusing (SF). Numerical computations are performed for typical parameters of relativistic laser-plasma interaction: magnetic field B = 10-100 MG; intensity I = 1016 to 1020 W/cm2; laser frequency ω = 1.1 × 1015 s−1; cyclotron frequency ωc = 1.7 × 1013 s−1; electron density ne = 2.18 × 1020 cm−3. From the calculations, we confirm that a circularly polarized wave can propagate in different regimes for both the modes, and explicitly indicating enhancement in wave propagation, beam focusing/self-guiding and penetration of E-mode in presence of magnetic field. 相似文献
11.
E. Coetsee 《Physica B: Condensed Matter》2009,404(22):4431-4435
Three different gases (nitrogen (N2), oxygen (O2) and argon (Ar)) were used as background gases during the growth of pulsed laser deposition (PLD) Y2SiO5:Ce thin films. A Krypton fluoride laser (KrF), 248 nm was used for the PLD of the films on silicon (Si) (1 0 0) substrates. The effect of the background gases on the surface morphology, crystal growth and luminescent properties were investigated. All the experimental parameters, the gas pressure (455 mT), the substrate temperature (600 °C), the pulse frequency (8 Hz), the number of pulses (4000) and the laser fluence (1.6±0.2) J/cm2 were kept constant. The only parameter that was changed during the deposition was the ambient gas species. The surface morphology and average particle sizes were monitored with scanning electron microscopy (SEM) and atomic force microscopy (AFM). X-ray diffraction (XRD) and Auger electron spectroscopy (AES) were used to determine the crystal structure and composition, respectively. Cathodo- (CL) and photoluminescence (PL) were used to measure the luminescent intensities for the different phosphor thin films. The nature of the particles, ablated on the substrate, is related to the collisions between the ejected particles and the ambient gas particles. The CL and PL intensities also depend on the particle sizes. A 144 h (coulomb dose of 1.4×104 C cm−2) electron degradation study on the thin films ablated in the Ar gas environment resulted in a decrease in the main CL intensity peak at 440 nm and to the development of a new very broad luminescent peak spectra ranging from 400 to 850 nm due to the growth of a SiO2 layer on the surface. 相似文献
12.
The self-broadening coefficients and intensities of approximately 460 of the strongest water vapour lines (intensity S ? 1.5 × 10−23 cm molec−1) in the spectral region 5000-5600 cm−1 have been derived from new laboratory measurements. The derived line intensities are on average in a good agreement with those in HITRAN-2001 (v.11.0) (within 0.5% for total band intensity). Self-broadening coefficients are compared with values estimated from the HITRAN-2001 foreign-broadening coefficients. Comparison has been also made with the recent HITRAN-2004 (v.12.0) compilation, which revealed marked systematic differences in the self-broadening coefficients (up to 20%) and in the line intensities (up to 5%). The possible reasons for these deviations are discussed. 相似文献
13.
The r.f. discharge of sputtering silicon target using argon-oxygen-nitrogen plasma was investigated by optical emission spectroscopy. Electronic temperature (Te) and emission line intensity were measured for different plasma parameters: pressure (from 0.3 to 0.7 Pa), power density (0.6-5.7 W cm−2) and gas composition. At high oxygen concentration in the plasma, both Te and the target self-bias voltage (Vb) steeply decrease. Such behaviour traduces the target poisoning phenomenon. In order to control the deposition process, emission line intensity of different species present in the plasma were compared to the ArI (λ = 696.54 nm) line intensity and then correlated to the film composition analysed by Rutherford Backscattering Spectroscopy. 相似文献
14.
Raman spectra of bismuth ferrite (BiFeO3) over the frequency range of 100-1500 cm−1 have been systematically investigated with different excitation wavelengths. The intensities of the two-phonon modes are enhanced obviously under the excitation of 532 nm wavelength. This is attributed to the resonant behavior when incident laser energy closes to the intrinsic bandgap of BiFeO3. The Raman spectra of BiFeO3 excited at 532 nm were measured over the temperature range from 77 to 678 K. Besides the abnormal changes of the peak position and the linewidth of the A1 mode at 139 cm−1, the prominent frequency shift, the line broadening and the decrease of the intensity for the two-phonon mode at 1250 cm−1 were observed as the temperature increased to Néel temperature (TN). All these results indicate the existence of strong spin-phonon coupling in BiFeO3. 相似文献
15.
The absorption spectrum of dideuterated water, D2O, has been recorded between 8800 and 9520 cm−1 by intracavity laser absorption spectroscopy (ICLAS) based on a vertical external cavity system emitting laser (VeCSEL) and by high sensitivity Fourier Transform spectroscopy. The combined analysis of the spectra has allowed attributing 1223 transitions to the D2O species. The spectrum assignment was performed on the basis of the recent results of variational calculations based on an optimized potential energy surface of D2O. A set of 687 energy levels was derived from transitions assigned to eight upper vibrational states, 577 of them being reported for the first time. A detailed line list has been generated. The line intensities were retrieved mainly from the FTS spectrum and the absolute integrated intensities of the 2v1 + v2 + v3 and the v2 + 3v3 bands dominating the spectrum have been determined. 相似文献
16.
Silver nanoparticles have been prepared using hydrogen gas as the reducing agent for silver nitrate and poly(vinyl pyrrolidone) as the capping agent; the reaction was carried out at 70 °C for 3 h. The size of the nanoparticles was found to be about 20 nm as analyzed using transmission electron micrographs. The X-ray diffraction pattern revealed the face-centered cubic (fcc) structure of silver nanoparticles. The linear absorption of Ag nanoparticles, α, is obtained about 3.71 cm−1. The non-linear refractive indices of silver nanoparticles were defined by the z-scan technique using CW He-Ne laser (λ = 632.8 nm) at different incident intensities. The magnitude of non-linear refractive index (n2) was measured to be in the order of 10−7 (cm2/W) with a negative sign. Therefore self-defocusing phenomena is taking placed for Ag nanoparticles. 相似文献
17.
Very weak water vapor absorption lines have been investigated by intracavity laser absorption spectroscopy (ICLAS) in the 11 335-11 947 and 12 336-12 843 cm−1 spectral regions dominated by the ν1 + 3ν2 + ν3 and ν2 + 3ν3 bands, respectively. A detectivity on the order of αmin ∼ 10−9 cm−1 was achieved with an ICLAS spectrometer based on a Ti: Sapphire laser. It allowed detecting transitions with an intensity down to 5 × 10−28 cm/molecule which is about 10 times lower than the weakest line intensities previously detected in the considered region. A line list corresponding to 1281 transitions with intensity lower than 5 × 10−26 cm/molecule has been generated. A detailed comparison with the line lists provided by the HITRAN database and by recent investigations by Fourier transform spectroscopy associated with very long multi pass cell is presented. The rovibrational assignment performed on the basis of the ab initio calculations of Schwenke and Partridge, has allowed for determining 176 new energy levels belonging to a total of 16 vibrational states. 相似文献
18.
T. Le Barbu V. Zéninari B. Parvitte G. Durry 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,98(2):264-276
A diode laser spectrometer was used in the laboratory to study 13CO2 and 18O12C16O line intensities and self-broadening coefficients near 2.04 μm. The spectral region ranging from 4896 to 4903 cm−1, which is suitable for in situ laser sensing of both isotopologues in the lower Martian atmosphere, was investigated using a distributed feedback GaInSb diode laser. Five lines of the (2 00 1)II←(0 0 0) band of 13CO2 and seven lines of the (2 00 1)II←(0 0 0) band of 18O12C16O were carefully revisited. The measured intensities and self-broadening coefficients were thoroughly compared with relevant molecular databases. 相似文献
19.
Jamel Salem Jean-Pierre Bouanich Jacques Walrand 《Journal of Molecular Spectroscopy》2004,225(2):174-181
Using a tunable diode-laser spectrometer self-broadening coefficients and absolute intensities have been measured for 26 lines of PH3 at 298 K in the QR branch of the ν2 band and the PP and RP branches of the ν4 band. The recorded lines with J values ranging from 2 to 14 and K from 0 to 11 are located in the spectral range 995-1093 cm−1. Self-broadening coefficients have also been measured at 173.4 K for nine of these lines. The collisional widths and line strengths are obtained by fitting each spectral line with different theoretical profiles. The results obtained for the line intensities are in good agreement with recent measurements [J. Mol. Spectrosc. 215 (2002) 178]. The self-broadening coefficients are also calculated on the basis of a simple semiclassical model involving only the electrostatic interactions. A satisfactory agreement is obtained except for high J values or K values equal to J, for which the calculated results are notably underestimated. By comparing broadening coefficients at room and low temperatures, the temperature dependence of these broadenings has been determined both experimentally and theoretically. 相似文献
20.
M. Riaz 《Optics Communications》2006,263(2):267-274
We present first measurements on the resonance enhanced three-photon excitation in thallium, using a Nd:YAG laser pumped dye laser in conjunction with a thermionic diode ion detector. The even-parity 6s2ns2S1/2 (15 ? n ? 31) and nd 2D5/2 (13 ? n ? 42) Rydberg states have been observed. The measured level energies reveal a dynamic shift from the photoabsorption values, which is decreasing with increasing n, while the asymmetry in the line profile is observed to be increasing with increasing n. In addition, an autoionising level (sp24P3/2) adjacent to the ionization threshold has been observed and quantitatively analyzed using the Fano’s photoionization cross-section relation for an isolated autoionising resonance. 相似文献