Analysis of neutron diffraction data in the case of high-scattering cells

Petrillo, C.; Sacchetti, F.

doi:10.1107/s0108767389013000

Cited by 42 publications

(24 citation statements)

References 3 publications

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“…[3] for the He-Xe inwhere y, rn, and A are smooth functions of Q, calculated following Ref. [8] and reported in Table I for some selected Q values. As far as the neutron-beam profile impinging on the sample is concerned, it has been found to be quite well represented by a Gaussian shape.…”

Section: Methodsmentioning

confidence: 99%

Structure of the He-Xe mixture near the 30-MPa demixing curve atT=294 K

et al. 1992

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We report measurements of the neutron-scattering differential cross section for the He-Xe mixture in the two coexisting states at T=294 K on the 30-MPa isobaric section of the demixing surface corresponding to Xe molar concentration of 0.78 and 0.48, respectively, and for pure orthobaric liquid Xe having the same number density as in the 0.78 mixture. From these data, the total structure factors have been extracted. For the same thermodynamic states we also performed molecular-dynamics simulations using different interatomic potentials. Analyzing the partial pair-correlation functions, we find that, as already found at lower pressure, in this case, where the He concentration is noticeably higher, the partial structure factor of Xe is also essentially unaffected by the presence of He. This supports a simple picture of the He-Xe gas-gas dernixing transition in terms of the liquid-gas transition of pure Xe. Analyzing the He-Xe correlations in the mixture, we also discuss the role played by He in the gas-gas immiscibility transition.PACS number(s): 61.12.q, 61.20.Ja, 61.25.Bi

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Section: Methodsmentioning

confidence: 99%

Structure of the He-Xe mixture near the 30-MPa demixing curve atT=294 K

et al. 1992

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“…The functions ? :(Q), m~(Q) and A:(Q) occurring in the previous analysis have been calculated using a program [25] that generalizes [22] to the case of a nonhomogeneous scatterer (cryostat, cell and sample). We evaluate numerically all the different single-and double-scattered intensities, and from them we obtain y:(Q) and m:(Q) [21].…”

Section: {I-ic5mentioning

confidence: 99%

Orientational correlations in liquid CO: neutron-diffraction measurements

et al. 1990

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The structure factors for saturated liquid CO have been measured at 83.5 K and 121.9 K by neutron diffraction over a range of momentum transfer 0.5 ~< Q ~< 16 A-1. The data were analysed to derive information about orientational correlations. No evidence was found for such correlations. Moreover, a new analysis of previous data on liquid N 2 at 77 K showed that in this case also the orientational correlations are undetectable.

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“…To derive the appropriate scattering from the sample, it is necessary to subtract the multiple scattering contribution. The multiple scattering contribution is obtained using an appropriate simulation procedure 22 which is used also to determine the appropriate sample transmission T s . The final results for the coherent intensity, measured at two temperatures just below and just above the glass transition temperature, were found to be temperature independent within the experimental errors.…”

Section: Methodsmentioning

confidence: 99%

Neutron scattering investigation of high-frequency dynamics in glassy glucose

et al. 2012

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The vibrational dynamics of vitreous glucose has been investigated by means of inelastic neutron scattering experiments, exploiting the coherent scattering cross section of deuterium in a fully deuterated sample and the high incoherent scattering cross section of hydrogen in a hydrogenated sample. The first part of the experiment allowed a rather detailed investigation of the collective dynamics in the THz range. The second part of the experiment was used to derive some information on the vibrational density of states of the system. The experiment confirms the presence of a propagating vibrational mode which is the natural extension at THz frequencies of the lower frequencies longitudinal sound mode. In addition, a second mode is also observed at a lower and almost constant frequency, showing an increasing intensity on reducing the wavelength. By comparing the dispersion relations of these collective modes to the experimental density of states, a possible relation between the low frequency mode and the well known excess of low frequency modes, that is, the boson peak, is identified.

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Analysis of neutron diffraction data in the case of high-scattering cells

Cited by 42 publications

References 3 publications

Structure of the He-Xe mixture near the 30-MPa demixing curve atT=294 K

Structure of the He-Xe mixture near the 30-MPa demixing curve atT=294 K

Orientational correlations in liquid CO: neutron-diffraction measurements

Neutron scattering investigation of high-frequency dynamics in glassy glucose

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