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M Lepère R Gobeille V.Malathy Devi M.A.H Smith B Aoaeh A.W Mantz 《Journal of Molecular Spectroscopy》2004,224(1):7-12
We have analyzed the methyl fluoride RQ(J,0)Q branch lines located near 1475 cm−1 using a simultaneous multi-spectrum fitting technique. In this analysis we have used previously recorded diode-laser data in which we collected many data points covering only one or two Q branch lines in a particular run. The analysis consists of simultaneously fitting 57 spectra collected with numerous pressure and path length conditions for all absorption lines. The data are concatenated to create one continuous spectrum of the Q branch. We have determined the intensity and self-broadened widths at 296 K for 23 RQ(J,0) lines. 相似文献
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Lepère M Valentin A Henry A Camy-Peyret C Blanquet G Populaire JC Mantz AW 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(11):2413-2419
We studied the R(0) line profile in the CH4 v4 band from room temperature to 188 K with N2 as a perturber, to 100 K with O2 as perturber, and from room temperature to 15 K using He as a perturber. The N2 and O2 measurements were performed over a total pressure range of 15-110 mbar, and for the He measurements the maximum sample pressure at 15 K was 1.10 mbar. Broadening parameters were determined, taking into account the confinement narrowing (Dicke effect), and narrowing parameters, deduced from the soft or hard collision model, are compared with the dynamic friction coefficient calculated values. We also obtained preliminary values for the temperature dependence of the N2, O2 and He line broadening parameters for this transition. 相似文献
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ZINDO semiempirical calculations on the Ni(CN)(4)(2-) ion were performed, and ground-state energies for all 41 valence-orbital-based MOs and orbital transition components of the two lowest energy fully allowed electronic transitions are reported. Gaussian 94 was used to calculate ground-state energies as a comparison. The ground-state energies using ZINDO compare much more favorably with those found through ab initio techniques than with those from a reported INDO calculation. The found electronic transitions agree substantially with earlier assignments with the exception that several orbital transitions are required to adequately model the lowest energy allowed x,y-polarized experimental transition. Calculation parameters were optimized to give excellent agreement with experiment and may serve well for more complex arrangements of this ion. 相似文献
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Development of a stabilized low temperature infrared absorption cell for use in low temperature and collisional cooling experiments 总被引:1,自引:0,他引:1
Valentin A Henry A Claveau C Camy-Peyret C Hurtmans D Mantz AW 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(14):227-3482
We have constructed a stabilized low temperature infrared absorption cell cooled by an open cycle refrigerator, which can run with liquid nitrogen from 250 to 80K or with liquid helium from 80K to a few kelvin. Several CO infrared spectra were recorded at low temperature using a tunable diode laser spectrometer. These spectra were analyzed taking into account the detailed effects of collisions on the line profile when the pressure increases. We also recorded spectra at very low pressure to accurately model the diode laser emission. Spectra of the R(2) line in the fundamental band of 13CO cooled by collisions with helium buffer gas at 10.5K and at pressures near 1 Torr have been recorded. The He-pressure broadening parameter (gamma(0) = 0.3 cm(-1) atm(-1)) has been derived from the simultaneous analysis of four spectra at different pressures. 相似文献
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To clarify the role played by water in facilitating long-range DNA charge transport, carefully designed, state-of-the-art, self-interaction corrected density-functional quantum mechanical and molecular mechanical (SIC-QM/MM) simulations are performed for the first time on two ionized adenine:thymine bridge models in explicit water solvent at finite temperature. For random solvent configurations, the charge is partially delocalized. However, a charge localization on different, well-separated adenines can be induced and is correlated with a restructuring of their first solvation shells. Thus, the importance of water in the mechanism of long-range charge transport is explicitly demonstrated, and the microscopic conditions for a charge localization are revealed. 相似文献
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Mantz YA Gerard H Iftimie R Martyna GJ 《Journal of the American Chemical Society》2004,126(13):4080-4081
The cis-trans isomerization of N-methylacetamide, a molecular model of the polypeptide chain, is examined via umbrella sampling Car-Parrinello MD and classical MD, in both gas and solution phases at 300 K. A new analysis of the C(O)-N bond interconversion and a full examination of the solvent shell structure are presented. 相似文献
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D. Mondelain C. Camy-Peyret W. Deng S. Payan A.W. Mantz 《Applied physics. B, Lasers and optics》2008,90(2):227-233
The impact of precise spectroscopic measurements on the P(9) multiplet in the ν3 band of 12CH4, obtained using a newly developed cold Herriott cell coupled with a tunable diode laser spectrometer, is examined in the
context of remote sensing of methane in the atmosphere. More specifically, the influence of the air-broadening temperature
dependence, of line narrowing and of line-mixing effects is assessed when fitting high resolution atmospheric spectra recorded
from a balloon in the solar occultation mode. This is achieved by considering residuals and retrieved methane volume mixing
ratio profiles. By combining data from previous studies together with new measurements, the expression for the temperature
dependence of the broadening coefficient has been revisited. It is shown that a correcting factor applied to the usual law
gives better results, when considering all the available measurements from room temperature down to about 10–20 K, as compared
to the usual expression of the width versus temperature. These results clearly demonstrate that collision broadening is more
sensitive to long-range attractive forces when the temperature is decreased.
PACS 33.70.Jg; 34.20.-b 相似文献
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We formulate a holomorphic theory of gravity and study how the holomorphy symmetry alters the two most important singular
solutions of general relativity: black holes and cosmology. We show that typical observers (freely) falling into a holomorphic
black hole do not encounter a curvature singularity. Likewise, typical observers do not experience Big Bang singularity. Unlike
Hermitian gravity (Mantz and Prokopec in , 2008), holomorphic gravity does not respect the reciprocity symmetry and thus it is mainly a toy model for a gravity theory formulated
on complex space-times. Yet it is a model that deserves a closer investigation since in many aspects it resembles Hermitian
gravity and yet calculations are simpler. Our study of light bending and gravitational waves in weak holomorphic gravitational
fields strongly suggests that holomorphic gravity reduces to general relativity at large distance scales. 相似文献