The precise crystal and molecular structure of melampodin, C(21)H(24)O(9), was determined from three-dimensional neutron diffraction data collected by counter techniques and phases by direct statistical methods. Crystals are orthorhombic, P2(1)2(1)2(1), a = 8,990(9), b = 14.352(14), c = 16.294(16) A, V = 2102 A(3), d(calc.) = 1.328 g.cm(-3), Z = 4 molecules per unit cell. The structural model w...

Subtle structural features such as disorder and anharmonic motion may be accurately characterized from nuclear density distributions (NDDs). As a viable alternative to neutron diffraction, this paper introduces a new approach named the nuclear-weighted X-ray maximum entropy method (NXMEM) for reconstructing pseudo NDDs. It calculates an electron-weighted nuclear density distribution (eNDD), exp...

This work presents the results for identification of chemical phases obtained by several laboratories as a part of an international nuclear forensic round-robin exercise. In this work powder X-ray diffraction (p-XRD) is regarded as the reference technique. Neutron diffraction produced a superior high-angle diffraction pattern relative to p-XRD. Requiring only small amounts of sample, µ-Raman sp...

Neutron diffraction has been used for engineering applications for nearly three decades. The basis of the technique is powder diffraction following Bragg’s Law. The measured diffraction patterns provide information about internal strains, texture and microstructure, which can be deduced from the peak positions, peak intensities, and peak widths, respectively. Most structural materials are aniso...

High real-space-resolution atomic pair distribution functions of La12xCaxMnO3 (x50.12, 0.25, and 0.33! have been measured using high-energy x-ray powder diffraction to study the size and shape of the MnO6 octahedron as a function of temperature and doping. In the paramagnetic insulating phase we find evidence for three distinct bond lengths which we ascribe to Mn-O, Mn-O-short, and Mn-O-long bo...