Interpretation of the extended continuous diffuse regions of x-ray thermal diffuse scattering of molecular crystals*

Diffuse X-Ray scattering from molecular crystals

“…However, as Amoro´s has pointed out (Amoro´s, Canut and De Acha, 1960), there are serious discrepancies between diffuse scattering domains and the molecular Fourier transform. Amoro´s introduced a new function, the difference Fourier function (DFT) , to correct for this (see Section 3.3 below).…”

“…Amoro´s and co-workers (Amoro´s and Amoro´s, 1968;Amoro´s, Canut and De Acha, 1960;Canut and Amoro´s, 1960) have studied X-ray diffuse scattering from molecular crystals such as hexamine, naphthalene and adipic acid (Amoro´s, Canut and De Acha, 1960). Using the molecular rigid body approximation and making the assumption of independent molecular motion, i.e.…”

“…Using the molecular rigid body approximation and making the assumption of independent molecular motion, i.e. no correlation between independent displacements in different unit cells, they introduced a new function, DFT, the difference between the scattered intensity of the molecules at rest and corrected for thermal motion (Amoro´s, Canut and De Acha, 1960;Canut and Amoro´s, 1960).…”

“…(34)) is valid only for molecules with independent translational vibrations. Amoro´s, Canut and De Acha (1960) used the DFT to calculate isodiffusion lines, corresponding to the diffuse continuous regions (bonds, sheets, almost spherical regions or columns). The position and shape of the continuous diffuse regions are related (in a reciprocal manner) to the shape and orientations of the individual molecules.…”

Correlation of intensity measurements of the diffuse scattering of X-rays

“…S~indor & Wooster (1963a, b) have surveyed the background work in this field and have described their detailed investigation of the thermal diffuse scattering from anthracene, comparing it with the scattering theoretically predicted on the basis of the differenceFourier-transform model of Amords, Canut & de Acha (1960). A more complete account of the whole subject is to be found in a recent book by Amords & Canut de Amords (1965), unfortunately not yet available in English translation.…”