Page 151 - 00. Complete Version - Progress Report IPEN 2014-2016

Nuclear Science and Technology | Progress Report 151

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 in-
credible new materials. Synthesis and char-
acterization of new materials requires uncon- Fig 1. Closed-cycle He refrigerator at the center of a six-detector PAC
ventional techniques. Phenomena in solid spectrometer (left). He-vapor cryostat to cool samples down to 1.2 K
(middle). Compact furnace at the center of a four-detector PAC spec-
materials and other substances, in gener- trometer to measure samples in the range from 300 K to 1350 K.
al, originates from small differences in their
electronic structure, which makes specifically
interesting to investigate new material and electronic charge and spin structure around
compounds from an atomic view in order to the probe. This information makes possible to
understand the origin of such phenomena. investigate properties of the crystal structure
Experimental measurements of hyperfine in- and or the origin of magnetic interactions in
teractions (interactions between the nuclear the material as well as the electronic struc-
moments and magnetic field or the electric ture around the probes. Due to the proxim-
field gradient) provide a very sensitive and ity of a nuclear research reactor, our labora-
accurate method to investigate condensed tory can use a variety of special radioactive
matter phenomena in many different solids, probe nuclei such as 140La, 111Ag, 111mCd,
as well as dynamic parameters in biomole- that are produced by neutron irradiation in
cules. The hyperfine interactions laboratory the IEA-R1 research reactor of IPEN, besides
of IPEN is using the nuclear technique of Per- the usual ones like 111In and 181Hf. Three
turbed gamma-gamma Angular Correlation PAC spectrometers: two with 4-detectors set-
(PAC) to measure hyperfine interactions to in- up and other with 6-detectors are available
vestigate a series of intermetallic compounds, in the Hyperfine Interactions laboratory. The
metal oxides and nanostructured materials facilities for sample environment in the lab-
which present interesting properties like su- oratory includes three closed-cycle He refrig-
perconductivity, magnetic order, phase tran- erators, one specific He-vapor device to cool
sitions, etc. Biological materials like proteins samples down to 1.2 K, and a compact fur-
and peptides are also a recent subject of inves- nace capable to reach 1350 K. A new fully
tigation. The PAC techniques uses radioactive digital PAC spectrometer is currently being
nuclei implanted into the material to be stud- set up with six new LaBr3 detectors.
ied that can probe magnetic hyperfine field
(mhf) and electric field gradient (efg) in de- A methodology using the 6Li ion beam
termined sites of crystalline structure of the from the Pelletron accelerator in the Phys-
material and provide information about the ics Institute of University of São Paulo to im-