Search results for "luminescence."

Programmatūras izstrāde elementāro procesu noteikšanai no eksperimentāliem datiem

2019

Darba gaitā tika izveidota uz C++ bāzēta programmatūra, kura analizē zinātniskās iekārtas izvaddatus, iegūtus mērot cieto vielu fotoluminiscences no ātrām dzišanas kinētikām. Tiek izmantotas divas metodes datu aproksimācijai ar vienu un divām dilstošām eksponentēm. Lietotāja izvēlētie lokāli uzglabātie faili, kuri ir iegūti eksperimenta laikā, tiek apstrādāti ar dažādām darbībām pēc kurām rezultāti tiek uzrādīti kā vienādojuma mainīgās vērtības un atkarībā no metodes var būt izrakstīti failā kā datu punkti. Kvalifikācijas darbā tiek iekļauta programmatūras prasību specifikācija un programmatūras projektējuma apraksts ar testēšanas dokumentāciju.

Synthesis, Electrochemistry, and Photophysics of Aza-BODIPY Porphyrin Dyes

2016

International audience; The synthesis of dyad and triad aza-BODIPY-porphyrin systems in two steps starting from an aryl-substituted aza-BODIPY chromophore is described. The properties of the resulting aza-BODIPY-porphyrin conjugates have been extensively investigated by means of electrochemistry, spectroelectrochemistry, and absorption/emission spectroscopy. Fluorescence measurements have revealed a dramatic loss of luminescence intensity, mainly due to competitive energy transfer and photoinduced electron transfer involving charge separation followed by recombination.

Photoluminescent Detection of Human T-Lymphoblastic Cells by ZnO Nanorods.

2020

The precise detection of cancer cells currently remains a global challenge. One-dimensional (1D) semiconductor nanostructures (e.g., ZnO nanorods) have attracted attention due to their potential use in cancer biosensors. In the current study, it was demonstrated that the possibility of a photoluminescent detection of human leukemic T-cells by using a zinc oxide nanorods (ZnO NRs) platform. Monoclonal antibodies (MABs) anti-CD5 against a cluster of differentiation (CD) proteins on the pathologic cell surface have been used as a bioselective layer on the ZnO surface. The optimal concentration of the protein anti-CD5 to form an effective bioselective layer on the ZnO NRs surface was selected. …

Visible luminescence of nanosilica: slow and fast contributions

2010

The structural disorder of a silica network probed by site selective luminescence of the nonbridging oxygen hole centre

2011

We studied the inhomogeneous distribution of the luminescence band associated with the nonbridging oxygen hole centre in silica through site selective excitation/detection of the zero phonon line by a tunable laser source. Defects induced in the bulk of synthetic samples by γ and β exposure exhibit an increase of the inhomogeneous width from 0.071 to 0.086 eV on increasing the irradiation dose from 2 × 10(6) to 5 × 10(9) Gy. We also investigated two defect variants stabilized at the surface of the silica nanoparticles, (≡ Si-O)3 Si–O* and (≡ Si-O)2(H-O)Si-O*, whose inhomogeneous width was measured to be 0.042 eV and 0.060 eV, respectively. These results can be accounted for by the structura…

Bright blue emission of synthesized silica nanoparticles conferred by surface defects

2013

Phonon Coupling Properties of Non Bridging Oxygen Hole Centers at a Silica Surface Probed by Site-Selective Luminescence Excitation

2008

Photoluminescence properties of point defects in Ge-doped fibers and preforms

2008

International audience; The optical properties of Ge-related point defects are often the most important parameter for the performances of silica based optical fibers. On one side their presence is often detrimental for the light transmission, on the other side some defect typologies exhibit modifications under radiation exposure thus offering the peculiar property of photosensitivity that is exploited to build technologically relevant devices such as fiber Bragg gratings.

Time resolved emission at 1.3 μm of a single InAs quantum dot by using a tunable fibre Bragg grating

2013

Photoluminescence and time resolved photoluminescence from single metamorphic InAs/GaAs quantum dots (QDs) emitting at 1.3 mu m have been measured by means of a novel fibre-based characterization set-up. We demonstrate that the use of a wavelength tunable fibre Bragg grating filter increases the light collection efficiency by more than one order of magnitude as compared to a conventional grating monochromator. We identified single charged exciton and neutral biexciton transitions in the framework of a random population model. The QD recombination dynamics under pulsed excitation can be understood under the weak quantum confinement potential limit and the interaction between carriers at the …

Energy Transport in SiO2 Crystals: Luminescence Excitation Spectra of Stishovite and α-Quartz

2022

The financial support of the Latvian Science Council Grant No lzp-2021/1-0215 and the funding of the University of Latvia as the Centre of Excellence within the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2, are greatly acknowledged.