I. Measurement of Diamagnetic Anisotropy in Single Crystals. II. The Crystal Structure of Monomethylurea

Citation

Gordon, Derck Alexander (1958) I. Measurement of Diamagnetic Anisotropy in Single Crystals. II. The Crystal Structure of Monomethylurea. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/WHH0-JE78. https://resolver.caltech.edu/CaltechETD:etd-10072004-143941

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. A method of determining the magnetic anisotropy of single crystals by measuring the torque exerted by a homogeneous magnetic field has been studied. Particular attention was paid to the overcoming of errors in the method of measurement, to the determination of the torsion constants of thin quartz fibers used as torque-measuring devices and to the method of mounting and orienting crystals for use in the investigation. It is believed that the newly devised procedures greatly increase the precision, accuracy and convenience of the measurements. Measurements of diamagnetic anisotropy in crystals of several simple organic and inorganic compounds and in two protein samples were made and are discussed in terms of crystal and molecular structure. Some time was spent in an effort to determine the crystal structure of monomethylurea using X-ray diffraction data in the literature and a trial structure suggested by the results of diamagnetic anisotropy measurements. A serious error in the published data was discovered, necessitating the rejection of much of the work. The intensities of the[...] [...] and [...] diffraction maxima were redetermined, and some conclusions about the crystal structure were drawn. Sufficient work has not been done to permit assignment of parameters to the individual atoms.

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