A5030720602- Photochemistry and Electron Transfer Studies
- Spectroscopy and Quantum Chemical Studies
- Fullerene Chemistry and Applications
- Luminescence and Fluorescent Materials
- Molecular Sensors and Ion Detection
- Advanced Chemical Physics Studies
- X-ray Diffraction in Crystallography
- Carbon Nanotubes in Composites
- Crystallization and Solubility Studies
- Molecular Junctions and Nanostructures
- Analytical Chemistry and Sensors
- Organic Light-Emitting Diodes Research
- Diamond and Carbon-based Materials Research
- Spectroscopy and Laser Applications
- Laser-induced spectroscopy and plasma
- Advanced Fluorescence Microscopy Techniques
- Graphene research and applications
- Quantum optics and atomic interactions
- Synthesis and Properties of Aromatic Compounds
- Laser Design and Applications
- Mass Spectrometry Techniques and Applications
- Various Chemistry Research Topics
- Advanced Thermodynamics and Statistical Mechanics
- Kidney Stones and Urolithiasis Treatments
- Optical Imaging and Spectroscopy Techniques
Institute for Biotechnology and Bioengineering
2018-2024
University of Lisbon
2015-2024
Instituto Superior de Tecnologias Avançadas
2022
Instituto Superior Técnico
2007-2018
Instituto Politécnico de Lisboa
1999-2018
Universidad de Huelva
2013
Instituto de Estructura de la Materia
1996-2012
Consejo Superior de Investigaciones Científicas
1979-2010
Instituto de Engenharia de Sistemas e Computadores Microsistemas e Nanotecnologias
2009
University of Regensburg
2008
Here, a comprehensive photophysical investigation of the emitter molecule
Fluorescence and phosphorescence are two forms of photoluminescence used in modern research practical applications. The early observations these phenomena, before the emergence quantum theory, highlight investigation into mechanism light emission. In contrast to incandescence, does not require high temperatures usually produce noticeable heat. Such a "cold light" was object an interesting controversy 19th century: it fit thermodynamics? applications, such as fluorescent tube, fluorescence...
An optical dual sensor for oxygen and temperature is presented that highly sensitive covers a broad range. Dual sensing based on luminescence lifetime measurements. The novel contains two luminescent compounds incorporated into polymer films. temperature-sensitive dye (ruthenium tris-1,10-phenanthroline) has temperature-dependent in poly(acrylonitrile) to avoid cross-sensitivity oxygen. Fullerene C70 was used as the oxygen-sensitive probe owing its strong thermally activated delayed...
C70 (like other fullerenes) is known to have a very weak fluorescence (ΦF ≅ 5 × 10-4), owing the high efficiency of triplet formation. In this work we show that, under appropriate conditions, quantum yield increases by one or two orders magnitude (up an estimated maximum value ΦF = 0.08), through mechanism delayed thermal fluorescence. We also report new estimate singlet−triplet gap (26 ± 2 kJ mol-1), obtained from temperature dependence This shown be in agreement with phosphorescence...
Dual luminescence (RTP and TADF) is observed in a series of donor–acceptor–donor molecules.
The barometric formula, relating the pressure p(z) of an isothermal, ideal gas molecular mass m at some height z to its p(0) z=0, is discussed. After a brief historical review, several derivations are given. Generalizations formula for nonuniform gravitational field and vertical temperature gradient also presented.
In efficient thermally activated delayed fluorescence (TADF) the excited chromophore alternates randomly between singlet and triplet manifolds a large number of times before emission occurs. this work, average cycles n is obtained shown to have simple experimental meaning: n+1 intensification factor prompt intensity, owing occurrence TADF. A new method data analysis for determination quantum yield formation, combining steady-state time-resolved in single plot, also presented. Application...
A new diethylenetriamine-derived macrocycle known as L, bearing 2-methylquinoline arms and containing m-xylyl spacers, was prepared in good yield by a one-pot [2 + 2] Schiff base condensation procedure, followed reduction with sodium borohydride. Up to now this is the first hexaazamacrocycle appended fluorophore units. Single-crystal X-ray diffraction determination of dinuclear zinc(II) complex L showed that metal centers are located at about 7.20(2) Å from one another. This exhibits only...
Tuning of photophysical properties by conformational control with dual RT phosphorescence in metal-free organic emitters.
A β-cyclodextrin labeled with seven naphthoyloxy chromophores was studied by steady-state and time-resolved fluorescence spectroscopy in order to get information on the dynamics of energy hopping between chromophores. The anisotropy recorded as a function excitation wavelength mixture methanol ethanol at 110 K (rigid glass). decay obtained under same conditions multifrequency phase-modulation technique upon 290 nm. data were analyzed interpreted basis theoretical model involving unique rate...
A sensitive and broad-ranged optical thermometer, based on the thermally activated delayed fluorescence of fullerene C70, is presented. It consists C70 molecularly dispersed in a polymer film. Several matrices were investigated. In absence oxygen intensity increases markedly with temperature. At 25 degrees C maximally by factor between 17 22, depending polymer, whereas at 100 can be 79 times higher. for temperatures above 20 C, red films so intense that it easily perceived naked eye. For...
Ultratrace quantities of oxygen can be determined at single spots as well spatially resolved, and over a temperature range more than 100 K, by exploiting the extremely efficient quenching delayed fluorescence fullerene C70 incorporated into matrices organosilica or ethyl cellulose.
Large-scale plasma produced in nitrogen gas at room temperature and pressures ranging from 4 × 10 3 to 1.2 5 Pa by high-power laserinduced dielectric breakdown (LIDB) has been investigated.Time-integrated optical spectra excited a CO 2 laser have measured analysed.The spectrum of the generated is dominated emission strong N + very weak 2+ atomic lines molecular features ofand B g -A u .The relative intensities 0-0 band heads (C-B) (B-X) systems are as compared with chemiluminescence formed...
Functionalized polymer nanoparticles react and store molecular oxygen for several weeks in the form of endoperoxides. On-demand controlled release singlet by particles is achieved thermolysis.
A model for long-range dipole–dipole energy transfer in spherical geometry is presented which, from steady-state or time-resolved fluorescence measurements, enables the determination of relative positions donor and acceptor inside sphere. Its application to micelles (sodium dodecyl sulphate, SDS, Triton X-100) did not lead a quantitative position probes [n-(9-anthroyloxy) stearic acids, n-AS, (n= 2, 3, 6, 9, 12) functional rhodamine cyanine dyes], this fact attributed probe-induced...
The optoelectronic and structural properties of hydrogenated amorphous silicon-carbon alloys (a-SiC:H) are studied over the entire compositional range carbon content. films prepared using low-power electron-cyclotron resonance (ECR) plasma-enhanced chemical vapor deposition. content was varied by different methane (or ethylene-)-to-silane gas phase ratios introducing ethylene) either remotely into plasma stream or directly through ECR source, together with excitation (hydrogen). Regardless...
Fluorescence depolarization by energy transfer resulting from dipole–dipole interaction (Förster type) is studied in donor–acceptor pairs of like and unlike chromophores at a fixed distance with random uncorrelated static orientations. For chromophores, the acceptor anisotropy decay shown to display three different extreme types behavior. When intrinsic rate much faster than both donor rate, decays positive value, then rises passes through maximum, finally tends negative limiting yielding...