The inelastic neutron scattering spectrum of chloroform in solution

1986 ◽  
Vol 42 (6) ◽  
pp. 721-723 ◽  
Author(s):  
Neil Everall ◽  
Joseph Howard ◽  
Clifford J. Ludman ◽  
Brian Boland ◽  
John Tomkinson
2000 ◽  
Vol 261 (1-2) ◽  
pp. 239-247 ◽  
Author(s):  
Francisco Partal ◽  
Manuel Fernández-Gómez ◽  
Juan J López-González ◽  
Amparo Navarro ◽  
Gordon J Kearley

1991 ◽  
Vol 187 (5) ◽  
pp. 455-458 ◽  
Author(s):  
Kosmas Prassides ◽  
T. John ◽  
S. Dennis ◽  
Jonathan P. Hare ◽  
John Tomkinson ◽  
...  

Author(s):  
PETER S. RISEBOROUGH

We have calculated the lowest energy quantized spectra of Intrinsically Localized Modes (ILMs) for the Fermi-Pasta-Ulam lattices. The quantized ILM spectra are composed of resonances in the two-phonon continuum and branches of infinitely long-lived excitations that are bound states formed from even numbers of phonons. For quartic anharmonicity and one atom per unit cell, the calculated ILMs are consistent with the results of previous calculations using the number conserving approximation. However, by contrast the ILM spectrum of the lattice with cubic interactions couples resonantly with the single-phonon spectrum and cannot be calculated within a number conserving approximation. Furthermore we argue that, by introducing a sufficiently strong cubic non-linearity, the quantized ILMs can be observed directly through the single-phonon inelastic neutron scattering spectrum. We compare our theoretical predictions with the recent experimental observation of breathers in NaI by Manley et al.


Author(s):  
R S Fishman ◽  
George Ostrouchov ◽  
Feng Ye

Abstract This work describes two methods to fit the inelastic neutron-scattering spectrum S(q, ω) with wavector q and frequency ω. The common and well-established method extracts the experimental spin-wave branches ωn(q) from the measured spectra S(q ,ω) and then minimizes the difference between the observed and predicted frequencies. When n branches of frequencies are predicted but the measured frequencies overlap to produce only m < n branches, the weighted average of the predicted frequencies must be compared to the observed frequencies. A penalty is then exacted when the width of the predicted frequencies exceeds the width of the observed frequencies. The second method directly compares the measured and predicted intensities S(q ,ω) over a grid {q i , ωj} in wavevector and frequency space. After subtracting background noise from the observed intensities, the theoretical intensities are scaled by a simple wavevector-dependent function that reflects the instrumental resolution. The advantages and disadvantages of each approach are demonstrated by studying the open honeycomb material Tb2Ir3Ga9.


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