A5054871267- Luminescence Properties of Advanced Materials
- Advanced Frequency and Time Standards
- Solid State Laser Technologies
- Glass properties and applications
- Scientific Measurement and Uncertainty Evaluation
- Inorganic Fluorides and Related Compounds
- Radioactive Decay and Measurement Techniques
- Lanthanide and Transition Metal Complexes
- GNSS positioning and interference
- Sensor Technology and Measurement Systems
- Quantum optics and atomic interactions
- Solid-state spectroscopy and crystallography
- Inertial Sensor and Navigation
- Optical Coherence Tomography Applications
- Atomic and Subatomic Physics Research
- Advanced MRI Techniques and Applications
- Nuclear Physics and Applications
- Quantum Information and Cryptography
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced Fiber Laser Technologies
- Electrochemical sensors and biosensors
- Quantum Mechanics and Applications
- Photorefractive and Nonlinear Optics
- Optical properties and cooling technologies in crystalline materials
- Laser-induced spectroscopy and plasma
Instituto Nacional de Metrologia, Qualidade e Tecnologia
2011-2024
Hospital Nossa Senhora das Graças
2016
Instituto de Pesquisas Energéticas e Nucleares
1996-2012
National Nuclear Energy Commission
1996-2008
Brazilian Center for Research in Energy and Materials
2002
A method for estimating the microscopic probability rate of phonon-assisted energy transfer between rare-earth $(3+)$ ions in solids was developed based on Dexter's theory transfer. The proposed this paper enables one to calculate overlap integral from fundamental cross-section spectra nonresonant involving a multiphonon generation both donor and acceptor sites. translation emission spectrum towards absorption scaled with $N$-phonon represents $m$-phonon band which performs acceptor....
The mechanism of the Yb3+→Er3+ energy transfer as a function donor and acceptor concentration was investigated in Yb3+–Er3+ codoped fluorozirconate glass. luminescence decay curves were measured analyzed by monitoring Er3+(4I11/2) fluorescence induced Yb3+(2F5/2) excitation. microparameters determined used to estimate Yb–Er rate an process assisted excitation migration among donors state (diffusion model). experimental rates from best fitting obtained using theoretical approach analog that...
The cross-relaxation probability (${\mathrm{sec}}^{\mathrm{\ensuremath{-}}1}$) involving the $^{5}$${\mathit{S}}_{2}$ and $^{5}$${\mathit{I}}_{8}$ levels of holmium ions in ${\mathrm{LiYF}}_{4}$ was investigated its concentration dependence determined. By using a random distribution function crystal, it possible to determine nonradiative for ion-ion energy transfer by dipole-dipole, dipole-quadrupole, quadrupole-quadrupole electric interactions. applied model shows that between...
The mechanism involved in the Tm3+ (3F4)→Ho3+ (5I7) energy transfer and (3H4, 3H6)→Tm3+ (3F4, 3F4) cross relaxation as a function of donor acceptor concentrations was investigated Tm–Ho-codoped fluorozirconate glasses. experimental rates were determined for Tm→Ho from best fit luminescence decay using an expression which takes into account Inokuti–Hirayama model localized donor-to-acceptor interaction solution. original solution derived fits well transient only low-concentrated systems....
The deactivation effects of the lowest excited states Er3+ and Ho3+ introduced in Er-or Ho-LiYF4 (YLF) crystals, codoped with Nd ions, were observed by activator’s fluorescence decays. In case Er:Nd:YLF, I13/24→4I15/2 I11/24→4I13/2 transitions at 1.5 2.7 μm, respectively, analyzed. I75→5I8 I65→5I7 2.1 2.9 investigated for Ho:Nd:YLF system. Laser excitations generated a tunable optical parametric oscillator used this investigation. use resonant laser excitation to induce allowed accurate...
In this paper we present a comparison between YLiF4:Yb:Tm and YLiF4:Yb:Tm:Nd systems identifying the most important processes that lead to 20 times enhancement of thulium blue upconversion emission, under excitation around 792 nm, for double sensitized system. Analysis 483 nm 1030 emissions samples with different concentrations Nd3+ ions showed energy transfer Yb3+ is main mechanism responsible in upconversion.
This work presents a compositional characterization of 1939's Thousand "Réis" and 1945's One "Cruzeiro" Brazilian coins, forged on aluminum bronze alloy. The coins were irradiated by Q-switched Nd:YAG laser with 4 ns pulse width energy 25mJ emitting at 1064nm reaching 3.10<sup>10</sup>Wcm<sup>-2</sup> (assured condition for stoichiometric ablation), forming plasma in small fraction the coin. Plasma emission was collected an optical fiber system connected to Echelle spectrometer. capability...
Ultraviolet (UV) fluorescence of Nd3+ ions induced by multistep laser excitation was investigated in Nd-doped LiYF4 and LiLuF4 crystals using a technique time-resolved spectroscopy. The observed UV luminescence due to transitions between the bottom 4f25d configuration 4f3 states ions. first absorption band configuration, which starts around 56 700 cm−1, excited three stepwise absorptions photons green (500–535 nm) from short pulse leading broad emission bands range (180–280 nm). An blue...
This paper presents a methodology for providing traceability to OCT measurements linked Length SI unit. The link primary length standard is provided by an interference microscope (IM). chosen transfer was step height gauge block. results IM and showed good agreement standards, such that the will be able perform reliable of complex surface topographies ensure scale. main uncertainty components were evaluated system. In addition, also used measuring roughness -a depth - in order test this...
Lasers from nine national metrology institutes (NMIs) were compared as part of the CCL-K11 ongoing key comparison, initiated by 13th meeting Comité Consultative des Longeurs (CCL) in 2007. The absolute frequency f component R(127) 11–5 transition molecular iodine was measured for these lasers following technical protocol CCL-K11. results measurements are compiled present report.
Low-coherence interferometric setups in the Fourier domain can experience false structures after transform procedure due to signal saturation; fact, these are located at multiple frequencies of original signal, also referred as harmonics. This study aids a better understanding this phenomenon. The aim present work was show that features be used improve differential axial resolution highly reflective samples. Using an optical coherence tomography system and calibrated step height standards,...
Ionospheric refraction introduces significant delay and fading in the electromagnetic signals. This makes ionosphere most harmful layer of Earth’s atmosphere to signals emitted by satellites, impacting reliability GNSS services. Depending on ionization level plasma signal frequency, these errors can vary from a few meters unavailability. The main factors influencing plasma’s are intensity solar radiation magnetic field. parameter evaluate behavior is Total Electron Content (TEC), existing...
Abstract Quantum mechanics, characterized by its intrinsically probabilistic nature, offers a promising avenue for random number generation, which is essential applications such as cryptography and computational simulations. With the recent advancements in quantum computing simulation, numerous studies have emerged utilizing these methods generation of numbers. This research delves into exploration Ascella photonic computer developed Quandela, renowned implementation single-photon-based...
The tetracycline-europium (Tc-Eu) complex is known to show emission at 615 nm. On addition of hydrogen peroxide (HP), a strongly fluorescent formed. In this paper it reported that the europium fluorescence intensity increased when urea added aqueous solution. It was conceived enhancement could be used determine (UHP) levels. This method simple, practical, and relatively free interference from coexisting substances, can applied successfully assess in biological samples, for example, on human...
This paper presents the implementation of cybersecurity procedures in remote calibration for time and frequency dissemination to be used position, navigation timing services. The method uses a P3 algorithm that combines P1 P2 codes from satellite link turn it free ionosphere refraction compare distant timescales. proposed is also implemented calculation reference scale UTC (Coordinated Universal Time) on key comparison CCTF-KOOl.UTC. Results between UTC(INXE) UTC(OP) has been prove...