Search results for "SPECTRA"
showing 10 items of 3542 documents
High resolution study of the and “hot” bands and ro-vibrational re-analysis of the polyad of the 32SO2 molecule
2011
Abstract The weak “hot” absorption bands, ν 1 + 2 ν 2 − ν 2 and 2 ν 2 + ν 3 − ν 2 , were analysed with high resolution using the Fourier transform interferometer Bruker IFS-120 HR. In order to make possible an analysis of the ν 1 + 2 ν 2 − ν 2 and 2 ν 2 + ν 3 − ν 2 bands, as the first step, we re-analysed considerably the stronger “cold” bands, ν 1 + ν 2 and ν 2 + ν 3 , which are located in the same spectral regions. As the result of analysis we obtained about 2650 and 2050 transitions (1069 and 1001 upper state ro-vibrational energy values) with Jmax. = 78, Kamax. = 27 and Jmax. = 68, Kamax. = 24 for the bands ν 1 + ν 2 and ν 2 + ν 3 , respectively, that is considerably higher than in the …
Global frequency and intensity analysis of the / / / band system of 12 C 2 H 4 at 10 μm using the D 2h Top Data System
2016
Abstract A global frequency and intensity analysis of the infrared tetrad of 12C2H4 located in the 600 – 1500 cm − 1 region was carried out using the tensorial formalism developed in Dijon for X2Y4 asymmetric-top molecules. It relied on spectroscopic information available in the literature and retrieved from high-resolution Fourier transform infrared spectra recorded in Brussels in the frame of either the present or previous work. In particular, 645 and 131 line intensities have been respectively measured for the weak ν10 and ν4 bands. Including the Coriolis interactions affecting the upper vibrational levels 101, 71, 41 and 121, a total of 10 757 line positions and 1645 line intensities ha…
Influence of the time-coherence of light on the absorption lineshapes of low-pressure gases
2001
Abstract A property of ultrashort laser pulses, their redshift by interaction with matter, is extended to ordinary time-incoherent light by a change of the scale of time. It appears that the matter must be a gas at a pressure uncommonly low in the labs, and that the gas must have a hyperfine structure. The relative frequency shift is constant as a Doppler shift; the images are not blurred because the interaction is space-coherent. In the presence of a redshift, the absorption lines cannot be seen because they are as wide as the shift. This interaction may produce a part of the cosmological redshift, the energy lost at high frequencies being transferred to the 2.7 K radiation. The interactio…
A direct study of the vibrational bending effect in line mixing: The hot degenerate 1110 ← 0110 transition of CO2
1997
Abstract The study of the isotropiv Raman Q -branch of a hot band Π ← Π allows one to establish a direct connection between the vibration-rotation angular momentum coupling and the resulting spectra. Due to the l -doubling, the Q -branch is split into two subbranches characterized by either even or odd rotational quantum number j . The vibrational bending reduces the rotational transfer rates inside each of these subbranches by a factor of about two and induces an inter-subbranch coupling. The expected propensity rule towards conservation of the parity index for high rotational levels is well observed. Calculated spectra are in excellent agreement with CARS experiments for the v 1 + v 2 ← v…
Computer simulations of hydrogen spectral line shapes in dense plasmas
2002
A new formalism has been elaborated for calculations of hydrogen line profiles emitted by dense plasmas. The main equation of this formalism has a similar form to a set of close-coupled, time-dependent partial differential equations. Calculated line shapes are broadened, shifted and asymmetrical. The formalism yields both shifts and widths of a line calculated within the same theoretical approach. A new basis of the appropriate subspace of the Hilbert space has been built. This basis gives an accurate description of the quadratic Stark effect, and the interaction of the emitter with field gradients. The computer simulation has been used to determine the emitter perturbations by electrons an…
Feasibility of photoelectron sources with sharp lines of stable energy between 20 and 80 keV.
2011
Photo-absorption of γ-rays in thin Al, Co, Ti, and Mo convertors was examined with the aim to produce quasi monoenergetic photoelectrons having an energy spread of 0.5-4.7eV about mean kinetic energies at discrete values between 18632 and 80321eV. The photoelectron rates were estimated for commercial photon sources of (241)Am, (119m)Sn, (125m)Te and (109)Cd with activities of 0.55-3.7GBq. Photoelectrons ejected by (241)Am γ- and X-rays from Co convertors were measured with two different electron spectrometers and obtained energy spectra were compared with Monte Carlo predictions.
New assignments in the 2μm transparency window of the 12CH4 Octad band system
2013
Abstract This paper reports new assignments of rovibrational transitions of 12 CH 4 bands in the range 4600–4887 cm −1 which is usually referred to as a part of the 2 μm methane transparency window. Several experimental data sources for methane line positions and intensities were combined for this analysis. Three long path Fourier transform spectra newly recorded in Reims with 1603 m absorption path length and pressures of 1, 7 and 34 hPa for samples of natural abundance CH 4 provided new measurements of 12 CH 4 lines. Older spectra for 13 CH 4 (90% purity) from JPL with 73 m absorption path length were used to identify the corresponding lines. Most of the lines in this region belong to th…
Collisional broadening and shifting parameters of the RamanQbranch ofH2perturbed byN2determined from speed-dependent line profiles at high temperatur…
1996
The broadening and shifting of the {ital Q} branch of H{sub 2} diluted in N{sub 2} are studied at temperatures between 300 and 1200 K. (i) In order to account for the observed anomalies (asymmetric profiles and nonlinearity of the linewidth versus perturber concentration), the results are interpreted using a speed-dependent model in its general form. This model introduces the speed dependence of the shift and the broadening. In contrast with the previous H{sub 2}{endash}rare-gas studies, the high-temperature measurements prove the necessity to include speed-dependent broadening that was ignored in the previous studies. (ii) Concomitantly, we report as well pure H{sub 2} results including Ra…
The complex behaviour of the microquasar GRS 1915+105 in theρclass observed withBeppoSAX
2011
BeppoSAX observed GRS 1915+105 on October 2000 with a long pointing lasting about ten days. During this observation, the source was mainly in the rho class characterized by bursts with a recurrence time of between 40 and 100 s. We identify five segments in the burst structure and accumulate the average spectra of these segments during each satellite orbit. We present a detailed spectral analysis aimed at determining variations that occur during the burst and understanding the physical process that produces them. We compare MECS, HPGSPC, and PDS spectra with several models. Under the assumption that a single model is able to fit all spectra, we find that the combination of a multi-temperatur…
Microscopic Dynamics of Hard Ellipsoids in their Liquid and Glassy Phase
2001
To investigate the influence of orientational degrees of freedom onto the dynamics of molecular systems in its supercooled and glassy regime we have solved numerically the mode-coupling equations for hard ellipsoids of revolution. For a wide range of volume fractions $\phi$ and aspect ratios $x_{0}$ we find an orientational peak in the center of mass spectra $\chi_{000}^{''}(q,\omega)$ and $\phi_{000}^{''} (q,\omega)$ about one decade below a high frequency peak. This orientational peak is the counterpart of a peak appearing in the quadrupolar spectra $\chi_{22m}^{''}(q,\omega)$ and $\phi_{22m}^{''}(q,\omega)$. The latter peak is almost insensitive on $\phi$ for $x_{0}$ close to one, i.e. f…