Inelastic Scattering of Thermal Neutrons by Liquid Sodium and Lead

Desai, Rashmi C.; Yip, Sidney

doi:10.1103/physrev.180.299

Cited by 12 publications

(6 citation statements)

References 28 publications

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“…Further, for large Q, B(Q) tends to zero so that equation (8) has the same limits at high Q as equation (7).…”

Section: Models For Normal Benzenementioning

confidence: 88%

“…The situation concerning coherent scatterers is much less well developed both experimentally and theoretically. Experimental measurements are available for argon [5], deuterated methane [6], liquid metals such as sodium [7] and lead [8] and the complex liquids selenium and tellurium [9]. Previously, however, the only material studied in both the coherent and incoherent form has been CH4/CD 4 [6] and in this case the considerable difference in the moment of inertia complicates the comparison.…”

Section: Ae(q T)= 2h'd'(t)q 2mentioning

confidence: 99%

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The quasi-elastic scattering of neutrons from C₆H₆and C₆D₆

Winfield

Ross

1972

Molecular Physics

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The quasi-elastic scattering of cold neutrons from liquid and solid C6H6 and C6D6 has been measured at temperatures between 260 K and 325 K for incident wavelengths between 4"07 ~_ and 7"05 A and for angles of scatter between 20 ~ and 90 ~ by means of a chopper time-of-flight apparatus. From the results, the total quasi-elastic intensity and the width of the corresponding broadening, presumed Lorentzian, were extracted. The broadening of the incoherent component in the scattering is discussed in terms of various models designed to combine the effects of centre of mass and jump rotational diffusion. All the models could be fitted to the results, using a root-meansquare jump length approximately equal to the nearest H-H distance. Using the 'effective mass approximation' the model can be extended to cover the coherent contributions to the scattering. When this is done, it is found that the fit is rather better if the rotational jumps are assumed not to contribute to the coherent broadening. The mean interval between jumps at 293 K was found to be 2"2 + 0'5 x 10 -*2 s with an activation energy of 2"1 ___ 0'6 kcal/mole, in good agreement with 1'4 • 10 -12 s and 1"8 kcal/mole obtained by N.M.R. techniques.

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“…Further, for large Q, B(Q) tends to zero so that equation (8) has the same limits at high Q as equation (7).…”

Section: Models For Normal Benzenementioning

confidence: 88%

Section: Ae(q T)= 2h'd'(t)q 2mentioning

confidence: 99%

The quasi-elastic scattering of neutrons from C₆H₆and C₆D₆

Winfield

Ross

1972

Molecular Physics

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“…In convolution approximation [12], it is given as where S(Q), the static structure factor, is the Fourier transform of the equilibrium pair-correlation function.…”

Section: (7)mentioning

confidence: 99%

“…where The coherent scattering function S(Q, o) as a function of Q attracts considerable attention since it gives information about the co-operative modes. In convolution approximation [12], it is given as where S(Q), the static structure factor, is the Fourier transform of the equilibrium pair-correlation function.…”

Section: (7)mentioning

confidence: 99%

Dynamical Correlations and Phonon Dispersion in a Liquid Binary Alloy

Bhandari

Pratap

Saxena

et al. 1992

Physica Status Solidi (b)

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Theory of Brownian motion of particles in static harmonic well approximation is applied to study the vibrational dynamics of liquid Na,Cs,-, (x = 0.5; 0.85) alloys. Dynamical variables like velocity autocorrelation function, power spectrum, and the mean square displacement are computed. The effective interatomic potential of the alloy used is obtained through the pair-potentials of individual components. The co-operative motion of atoms is described in terms of spectral functions of longitudinal current -current correlation functions which are obtained through the mean square displacement. These spectral functions of longitudinal current-current correlations are then used to get phonon dispersion in the alloy. The results are compared with the recently reported quasi-dispersion results of neutron inelastic scattering (NIS) experiments. Good qualitative agreement is observed.Um die Schwingungsdynamik der fliissigen Na,Cs, -x (x = 0,5; 0,85)-Legierungen zu untersuchen, wird die Theorie der Brownschen Bewegung auf Teilchen in statischer harmonischer Oszillatornaherung angewendet. Dynamische Variablen, wie Geschwindigkeits-Autokorrelationsfunktion, Leistungsspektrum und mittleres Verschiebungsquadrat werden numerisch berechnet. Das fur die Arbeit benutzte effektive interatomare Potential der Legierung wird aus den Paarpotentialen der individuellen Komponenten erhalten. Die kooperative Bewegung der Atome wird mit den Spektralfunktionen der longitudinalen Strom-Strom-Korrelationsfunktionen beschrieben, die aus dem mittleren Verschiebungsquadrat erhalten werden. Diese Spektralfunktionen der longitudinalen Strom-Strom-Korrelation werden dann benutzt, urn die Phononendispersion in der Legierung zu erhalten. Die Ergebnisse werden verglichen mit den kiirzlich veroffentlichten Quasidispersionsergebnissen von inelastischen Streuexperimenten (NIS) von Neutronen. Gute qualitative Ubereinstimmung wird beobachtet.

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“…The dynamical structure factor is then given as [7] where (r2(t)) is the mean-square displacement and S(q) the static structure factor.…”

Section: Theorymentioning

confidence: 99%

Dynamical Correlations in Liquid Metals K and Cs

Jain

Gupta

Saxena

1990

Physica Status Solidi (b)

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The theory of single particle motion in static harmonic well approximation is employed to study the dynamical correlations in potassium and cesium at their respective melting temperatures. Computation of dynamical variables like velocity autocorrelation function, power spectrum, and mean square displacement in both, potassium and cesium are made using the effective pair potential as obtained from the Ashcroft empty core model pseudopotential. The cooperative modes of motion of atoms is described in terms of the spectral functions of longitudinal current-current correlation which are obtained through the mean square displacement. Frequency corresponding to the peak positions in longitudinal current-current correlation functions are then plotted against the wave vector transfer.

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Inelastic Scattering of Thermal Neutrons by Liquid Sodium and Lead

Cited by 12 publications

References 28 publications

The quasi-elastic scattering of neutrons from C₆H₆and C₆D₆

The quasi-elastic scattering of neutrons from C₆H₆and C₆D₆

Dynamical Correlations and Phonon Dispersion in a Liquid Binary Alloy

Dynamical Correlations in Liquid Metals K and Cs

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Inelastic Scattering of Thermal Neutrons by Liquid Sodium and Lead

Cited by 12 publications

References 28 publications

The quasi-elastic scattering of neutrons from C6H6and C6D6

The quasi-elastic scattering of neutrons from C6H6and C6D6

Dynamical Correlations and Phonon Dispersion in a Liquid Binary Alloy

Dynamical Correlations in Liquid Metals K and Cs

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Product

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The quasi-elastic scattering of neutrons from C₆H₆and C₆D₆

The quasi-elastic scattering of neutrons from C₆H₆and C₆D₆