Page 5 - PR 2014 2016 07 Nuclear Science and Technology

Nuclear Science and Technology | Progress Report 147

Hyperfine interactions
in solids, nanoparticles,

and biomolecules

Zero-emission electric vehicles, data process-
ing and storage based on spin, mega magnets,
nanoparticles selectively delivering drugs to
tumor without interacting with the normal
body cells, all of these and much more new
achievements will be available in the near
future. Technological revolutions require
incredible new materials. Synthesis and
characterization of new materials requires Fig 1. Closed-cycle He refrigerator at the center of a six-detector PAC
unconventional techniques. Phenomena in spectrometer (left). He-vapor cryostat to cool samples down to 1.2
K (middle). Compact furnace at the center of a four-detector PAC
solid materials and other substances, in gen- spectrometer to measure samples in the range from 300 K to 1350 K.
eral, originate from small differences in their
electronic structure, which makes specifically
interesting to investigate new material and charge and spin structure around the probe.
compounds from an atomic view in order to This information makes possible to investi-
understand the origin of such phenomena. gate properties of the crystal structure and
Experimental measurements of hyperfine or the origin of magnetic interactions in the
interactions (interactions between the nuclear material as well as the electronic structure
moments and magnetic field or the electric around the probes. Due to the proximity of
field gradient) provide a very sensitive and ac- a nuclear research reactor, our laboratory
curate method to investigate condensed mat- can use a variety of special radioactive probe
140
ter phenomena in many different solids, as nuclei such as La, Ag, 111m Cd, that are pro-
111
well as dynamic parameters in biomolecules. duced by neutron irradiation in the IEA-R1
The hyperfine interactions laboratory of IPEN research reactor of IPEN, besides the usual
is using the nuclear technique of Perturbed ones like In and Hf. Three PAC spectrom-
181
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gamma-gamma Angular Correlation (PAC) to eters: two with 4-detectors setup and other
measure hyperfine interactions to investigate with 6-detectors are available in the Hyper-
a series of intermetallic compounds, metal fine Interactions laboratory. The facilities
oxides and nanostructured materials which for sample environment in the laboratory
present interesting properties like supercon- includes three closed-cycle He refrigerators,
ductivity, magnetic order, phase transitions, one specific He-vapor device to cool samples
etc. Biological materials like proteins and pep- down to 1.2 K, and a compact furnace capa-
tides are also a recent subject of investigation. ble to reach 1350 K. A new fully digital PAC
The PAC technique uses radioactive nuclei spectrometer is currently being set up with
implanted into the material to be studied six new LaBr detectors.
3
that can probe magnetic hyperfine field (mhf)
6
and electric field gradient (efg) in determined A methodology using the Li ion beam from
sites of crystalline structure of the material the Pelletron accelerator in the Physics Insti-
111
and provide information about the electronic tute of University of São Paulo to implant In