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Fast-Beam Laser Spectroscopy of Helium-like Silicon |
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| Authors: | Myers E. G. Redshaw M. Roeder B. |
| Affiliation: | 1.Departamento de Física, IFLP, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C.67, 1900, La Plata, Argentina ;2.Departamento de Química, Facultad de Ciencias Exactas, CINDECA (CONICET, CIC), 47 N○ 257, 1900, La Plata, Argentina ; |
| Abstract: | We have characterized a system of maghemite, γ-Fe2O3, nanosized particles prepared by a microemulsion method using an ionic surfactant. The Mössbauer spectra from 21 to 298 K evolve from a totally magnetically split signal at low temperatures to a single superparamagnetic (sp) doublet at 298 K with a blocking temperature of ≈150 K. The real component of the AC susceptibility (5≤ν≤104 Hz) displays a behavior characteristic of a system of interacting particles. A broad distribution of the particle sizes is revealed by the much higher average energy barrier obtained by AC susceptibility than Mössbauer. |
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