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1.
Periodica Mathematica Hungarica - 相似文献
2.
The rotational spectra of three low-energy conformers of thiodiglycol (TDG) (HOCH2CH2SCH2CH2OH) have been measured in a molecular beam using a pulsed-nozzle Fourier-transform microwave spectrometer. To determine the likely conformational structures with ab initio approach, conformational structures of 2-(ethylthio)ethanol (HOEES) (CH3CH2SCH2CH2OH) were used as starting points together with the consideration of possible intramolecular hydrogen bonding in TDG. Three lower-energy conformers have been found for TDG at the MP2=Full/6311G** level and ab initio results agree nicely with experimentally determined rotational constants. In addition, Stark measurements were performed for two of the three conformers for dipole moment determinations, adding to our confidence of the conformational structure matches between experimental observations and ab initio calculations. Of the three lower-energy conformers, one displays a compact folded-like structure with strong hydrogen bonding between the two hydroxyl groups and the central sulfide atom. Two other conformers have relatively open chain-like structures with hydrogen bonding between each of the hydroxyl groups to the central sulfur atom, of which one has pure b-type dipole moment according to the ab initio results. 相似文献
3.
V Correcher J Garcia-Guinea FJ Valle-Fuentes 《Journal of Thermal Analysis and Calorimetry》2006,83(2):439-444
In
this paper, novel results on the blue thermally stimulated luminescence (TSL)
emission of ulexite (NaCaB5O6(OH)6·5H2O)
have been studied. The four maxima appearing at 60, 110, 200 and 240°C
on the TSL glow curves of this borate could be respectively associated to:
(i) the first dehydration (NaCaB5O6(OH)6·5H2O→NaCaB5O6(OH)6·3H2O),
(ii) the creation-annihilation of the three-hydrated
phase, (iii) the Na-coordinated chains
dehydroxylation and the starting point of the alkali self-diffusion through
the lattice and (iv) the amorphisation
of the lattice. These results are fairly well correlated with the differential
thermal analyses (DTA), in situ thermal observations under environmental scanning
electron microscope (TESEM) and thermal X-ray diffraction (TXRD) techniques. 相似文献
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7.
R.D. SuenramF.J. Lovas D.F. PlusquellicA. Lesarri Y. KawashimaJ.O. Jensen A.C. Samuels 《Journal of Molecular Spectroscopy》2002,211(1):110-118
The rotational spectrum of dimethyl methylphosphonate (DMMP) has been studied using a pulsed molecular beam Fourier transform microwave spectrometer. The spectrum is complicated by the internal rotation motions of the three methyl tops in the molecule as well as an interconversion motion of the two methoxy groups. Here, we present the microwave spectrum, the ab initio calculations, and the assignment of the rigid-rotor A-symmetry state of the molecule. The rotational constants for this state are A=2828.753(2) MHz, B=1972.360(3) MHz, and C=1614.267(2) MHz. In the following paper, a group theoretical analysis is developed for DMMP. The observed conformation of the molecule has no point-group symmetry and all three electric-dipole selection rules are active, with c-type transitions being the most intense. Ab initio calculations were carried out at both the Hartree-Fock 6-31G* and MP2/6-311G* levels of theory. These calculations indicate that two low-energy conformations are possible separated by energies of less than 170 cm−1. Furthermore, the calculated lowest energy conformer is in agreement with the one observed experimentally. The relative energies of the two low-energy conformers rise from 34 cm−1 at the HF level to 170 cm−1 at the MP2 level. 相似文献
8.
The orthogonality-condition model (OCM), as an approximation method for calculating the overlap and potential overlap functions involved in the form factor of transfer reactions, is tested against microscopic cluster calculations for the 7Li = α + t system. The OCM overlap and potential overlap turn out to depend strongly on the OCM potential although the potentials are chosen so as to produce the same asymptotic phase. Excellent approximations to microscopic overlaps and potential overlaps are, however, obtained by optimizing the OCM potential, so that the OCM may reproduce the microscopic energy surface. In this way the dependence on the OCM potential is traced back to the underlying nucleon-nucleon force. 相似文献
9.
The low-temperature specific heat (LTSH) of the melt-quenched Ni81.5Px- B18.5?x amorphous alloy system, with 0 ? x ? 18.5, is presented. The decomposition of the LTSH into magnetic, lattice and electronic contributions shows that both Debye temperature θD and electronic specific heat coefficient decrease when the concentration of P increases.The electronic density of states N(EF), deduced from γ for various Ni-metalloid alloys, is plotted as a function of the average electronic concentration xZM, where x is the metalloid concentration and ZM is the chemical valence of M. Following Malozemoff et al.'s work, this plot is considered as a representation of the band structure and yields the change of the Fermi level with alloying. 相似文献
10.
Robert L. Kuczkowski Frank J. Lovas R.D. Suenram Robert P. Lattimer Kurt W. Hillig Arthur J. Ashe 《Journal of Molecular Structure》1981
The microwave spectra of 1,4-pentadiyne and 1,4-pentadiyne-1,5-d2 are assigned and rotational and centrifugal distortion constants obtained. A unique structure could not be determined. However, analysis of the moments of inertia indicates that the bond distances in C5H4 are close to typical values found in other related compounds. An interaction involving the acetylene moieties is evidenced by the derived bond angles. The data are consistent with either the central CCC angle being close to the tetrahedral value with the acetylene groups pushed away from linearity by approximately 3–4° or opening of the central CCC angle to about 113° along with linear acetylene groups. A range of structures between these two is also possible. The dipole moment is determined to be 0.516(5) D. 相似文献