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1.
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Structural formation yield of GeV centers from implanted Ge in diamond
/ Wahl, Ulrich (IST, Lisbon (main)) ; Correia, João Guilherme (IST, Lisbon (main)) ; Costa, Ângelo (Leuven U.) ; Lamelas, Afonso (Aveiro U.) ; Amaral, Vítor (Aveiro U.) ; Johnston, Karl (CERN) ; Magchiels, Goele (Leuven U.) ; Tunhuma, Shandirai Malven (Leuven U.) ; Vantomme, André (Leuven U.) ; Pereira, Lino M C (Leuven U.)
In order to study the structural formation yield of germanium-vacancy (GeV) centers from implanted Ge in diamond, we have investigated its lattice location by using the β$^{−}$ emission channeling technique from the radioactive isotope $^{75}$Ge (t$_{1/2}$ = 83 min) produced at the ISOLDE/CERN facility. $^{75}$Ge was introduced via recoil implantation following 30 keV ion implantation of the precursor isotope $^{75}$Ga (126 s) with fluences around 2 × 10$^{12}$–5 × 10$^{13}$ cm$^{−2}$. [...]
2024 - 16 p.
- Published in : Mat. Quant. Tech. 4 (2024) 025101
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Free Molecule Studies by Perturbed $\gamma - \gamma$ Angular Correlation: A New Path to Accurate Nuclear Quadrupole Moments
/ Haas, Heinz (CERN ; U. Aveiro (main)) ; Röder, Jens (CERN ; U. Aveiro (main)) ; Correia, Joao G (CERN ; IST, Lisbon (main)) ; Schell, J (CERN ; U. Duisburg-Essen) ; Fenta, Abel S (U. Aveiro (main)) ; Vianden, Reiner (Bonn U., HISKP) ; Larsen, Emil M H (U. Copenhagen (main)) ; Aggelund, Patrick A (U. Copenhagen (main)) ; Fromsejer, Rasmus (U. Copenhagen (main)) ; Hemmingsen, Lars B S (U. Copenhagen (main)) et al.
Accurate nuclear quadrupole moment values are essential as benchmarks for nuclear structure models
and for the interpretation of experimentally determined nuclear quadrupole interactions in terms of
electronic and molecular structure. Here, we present a novel route to such data by combining perturbed γ-γ
angular correlation measurements on free small linear molecules, realized for the first time within this
work, with state-of-the-art ab initio electronic structure calculations of the electric field gradient at the
probe site. [...]
2021 - 6 p.
- Published in : Phys. Rev. Lett. 126 (2021) 103001
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3.
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Quantum colour centers in diamond studied by emission channeling with short-lived isotopes (EC-SLI) and radiotracer photoluminescence
/ Pereira, Lino (KU Leuven, Quantum Solid State Physics (QSP), Belgium) ; Wahl, Ulrich (Instituto Superior Técnico, Universidade de Lisboa, Portugal) ; Correia, João Guilherme (Instituto Superior Técnico, Universidade de Lisboa, Portugal) ; Costa, Ângelo (CERN-TE, Geneva, Switzerland) ; David Bosne, Eric (Instituto Superior Técnico, Universidade de Lisboa, Portugal) ; Lima, Tiago (KU Leuven, Quantum Solid State Physics (QSP), Belgium) ; Moens, Janni (KU Leuven, Quantum Solid State Physics (QSP), Belgium) ; da Silva, Manuel (CICECO- Instituto de Materiais de Aveiro, Universidade de Aveiro, Portugal) ; Tunhuma, Malven (KU Leuven, Quantum Solid State Physics (QSP), Belgium) ; Vantomme, André (KU Leuven, Quantum Solid State Physics (QSP), Belgium) et al.
CERN-INTC-2020-037 ; INTC-P-562.
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2020.
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4.
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Ultra sensitive quantification of Hg$^{2+}$ sorption by functionalized nanoparticles using radioactive tracker spectroscopy
/ Amorim, Carlos O (Aveiro U. ; U. Aveiro (main)) ; Gonçalves, João N (Aveiro U.) ; Tavares, Daniela S (U. Aveiro (main)) ; Fenta, Abel S (Aveiro U. ; CERN ; Leuven U.) ; Lopes, Cláudia B (U. Aveiro (main) ; CIIMAR, Porto) ; Pereira, Eduarda (U. Aveiro (main)) ; Trindade, Tito (U. Aveiro (main)) ; Correia, João G (CERN ; IST, Lisbon (main)) ; Amaral, Vítor S (Aveiro U.)
/Isolde
We present an ultra sensitive method to quantify the uptake of Hg by dithiocarbamate functionalized magnetic nanoparticles using radioactive tracker spectroscopy. We show a lower limit of detection of about 10 fg L-1, much lower than any other known techniques used to determine the uptake of Hg (about 104 more sensitive), without the need of digesting or processing the sorption agent. [...]
2018 - 6 p.
- Published in : Microchem. J. 138 (2018) 418-423
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5.
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Perturbed Angular Correlation Study of the Static and Dynamic Aspects of Cadmium and Mercury Atoms Inside and Attached to a C60 Fullerene Cage
/ Das, Satyendra K (Bhabha Atomic Res. Ctr.) ; Guin, Rashmohan (Bhabha Atomic Res. Ctr.) ; Banerjee, Debasish (Bhabha Atomic Res. Ctr.) ; Johnston, Karl (CERN) ; Das, Parnika (Calcutta, VECC) ; Butz, Tilman (Leipzig U.) ; Amaral, Vitor S (U. Aveiro (main) ; Aveiro U.) ; Correia, Joao G (CERN ; ITN, Sacavem) ; Barbosa, Marcelo B (CERN ; ITN, Sacavem)
30 keV Cd-111m and 50 keV Hg-199m beams from ISOLDE were used to implant on preformed targets of C-60 with a thickness of 1 mg cm(-2). Endofullerene compounds, viz. [...]
2014 - 8 p.
- Published in : Z. Naturforsch. A 69 (2014) 611-618
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6.
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Perturbed angular correlations investigations on YMnO$_3$ multiferroic manganite
/ Mendonca, Tania Melo (Porto U.) ; Lopes, Armandina (Lisbon U., CFNUL) ; Goncalves, Joao Nuno (U. Aveiro) ; Correia, Joao (ITN, Sacavem) ; Tavares, Pedro (UTAD, Vila Real) ; Amaral, Vitor (U. Aveiro) ; Daries, Celine (Neel Lab, Grenoble) ; Araujo, Joao Pedro (Porto U.)
The Perturbed Angular Correlation (PAC) technique was applied to study the yttrium local environment in YMnO$_3$ multiferroic manganite. The electric field gradients (EFG) at the Y site have been measured as function of temperature, covering both ferroelectric and magnetic transitions. [...]
CERN-OPEN-2014-020.-
Geneva : CERN, 2010 - 6 p.
- Published in : Hyperfine Interact. 197 (2010) 83-88
Preprint: PDF;
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7.
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Dynamic off-centering of Cr$^{3+}$ ions and short-range magneto-electric clusters in in CdCr$_2$S$_4$
/ Oliveira, Gonçalo Nuno (Porto U.) ; Pereira, André Miguel (Porto U.) ; Lopes, Armandina Lima (Lisbon U., CFNUL) ; Amaral, João Sequeira (Aveiro U.) ; dos Santos, António (Oak Ridge) ; Ren, Yan (ANL, APS) ; Mendonca, Tania Manuela (Porto U.) ; Sousa, Célia Tavares (Porto U.) ; Amaral, Vitor Sequeira (Aveiro U.) ; Correia, João Guilherme (IST/ITN, Lisbon) et al.
The cubic spinel CdCr$_2$S$_4$ gained recently a vivid interest, given the relevance of relaxor-like dielectric behavior in its paramagnetic phase. By a singular combination of local probe techniques namely Pair Distribution Function and Perturbed Angular Correlation we firmly establish that the Cr ion plays the central key role on this exotic phenomenon, namely through a dynamic off-centering displacement of its coordination sphere. [...]
CERN-OPEN-2014-019.-
Porto : IFIMUP-IN, 2012 - 7 p.
- Published in : Phys. Rev. B 86 (2012) 224418
Preprint: PDF;
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8.
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Magnetic hyperfine field at Cr site in AgCrO$_2$ given by perturbed angular correlations
/ Oliveira, Gonçalo Nuno (Porto U.) ; Lopes, Armandina Lima (Lisbon U., CFNUL) ; Mendonca, Tania Manuela (Porto U.) ; Araújo, João Pedro (Porto U.) ; Moreira, Joaquim Agostinho (Porto U.) ; Almeida, Abílio (Porto U.) ; Amaral, Vitor Sequeira (Aveiro U.) ; Correia, João guilherme (IST/ITN, Lisbon)
This work presents an electric field gradient and magnetic hyperfine field study, in the AgCrO$_2$ multiferroic with triangular spin lattice. The temperature dependence of the electric field gradient (EFG) and magnetic hyperfine field (MHF) at Cr site was studied at ISOLDE via perturbed angular correlation measurements with the $^{111}$In probe, at room temperature and below the Neel temperature (T=21 K) down to presence of two distinct local environments. [...]
CERN-OPEN-2014-012.-
Porto : U., 2010 - 5 p.
- Published in : Hyperfine Interact. 197 (2010) 123-128
Preprint: PDF;
In : 3rd Joint International Conference on Hyperfine Interactions and International Symposium on Nuclear Quadrupole Interactions, CERN, Geneva, Switzerland, 12 - 17 Sep 2010, pp.123-128
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9.
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Atomic ordering of the fluorine dopant in the $HgBa_{2}CuO_{4+\delta}high-T_{c}$ superconductor
/ Correia, João Guilherme ; Amaral, Vitor S ; Araújo, João Pedro ; Bordet, P ; Haas, Heinz ; Le Floc'h, S ; Lopes, A M L ; Rita, E ; Carvalho-Soares, João
Lattice sites and collective ordering of fluorine atoms in oxygen- reduced samples of HgBa/sub 2/CuO/sub 4/ were investigated with the perturbed angular correlation technique by measuring the electric field gradients induced at /sup 199m/Hg nuclei. The experimental data were interpreted with the help of ab initio calculations of charge distributions for different fluorine configurations in Hg/sub m/Ba /sub 2m/Cu/sub m/O/sub 4m/F/sub n/, supercells. [...]
2005
- Published in : Phys. Rev. B 72 (2005) 144523-1-10
APS Published version, local copy: PDF;
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