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Stapleton, H.J. Brower, Keith LaMar 2011-05-20T16:40:29Z 2011-05-20T16:40:29Z 10000-01-01 1966 Measurements of the electron spin resonance spectra of first- and second-neighbor Nd3+ pairs in LaC13 and LaBr3 were made at 4, 20K and 9 kMc/sec, These studies were made on crystals doped from 0,1 to 2, a atomic percent with enriched even-even isotopes of neodymium, The observed spectra can be described in terms of a spin Hamiltoniam containing a Zeeman term and a traceless coupling tensor A .. between two effective spins each of magnitude 1J 1/20 This latter term represents an anisotropic effective spin interaction within the triplet levels of the system, About 5, 000 resonances due to allowed and forbidden transitions within these triplet levels were observed and fit to this Hamiltonian for various orientations of the magnetic field with respect to these crystals, Although a perturbation treatment was adequate for the analysis of the second -neighbor Nd3+ pair spectra, it was necessary to diagonalize the spin Hamiltonian in order to analyze the spectra associated with the first-neighbor Nd3+ pairs, The observed symmetry of the second-neighbor interaction tensors in these two salts suggests that the halide ions play an important role, By removing the dipolar contributions to A.. , quantitative 1J results regarding the nature of the nondipolar spin -spin interaction are obtained, No resonances attributable to pairs were detected at X-band in LaC13 doped with either Ce3+ or er3+ Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-05-20T16:40:29Z No. of bitstreams: 1 1966_brower.pdf: 3529572 bytes, checksum: 94480ae9d7a8b6dde26013013d2fd424 (MD5) Made available in DSpace on 2011-05-20T16:40:29Z (GMT). No. of bitstreams: 1 1966_brower.pdf: 3529572 bytes, checksum: 94480ae9d7a8b6dde26013013d2fd424 (MD5) Previous issue date: 1966 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-05-20T16:40:29Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:14:31-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Thesis U of I Only 6179038 http://hdl.handle.net/2142/23989 en 1966 Keith LaMar Brower electron spin resonance trivalent neodymium anhydrous lanthanum trichloride lanthanum tribromide doped crystals spin Hamiltoniam Zeeman term Electron spin resonance of trivalent neodymium pairs in anhydrous lathanum trichloride and lanthanum tribromide Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.