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I am a PhD Researcher that focuses on characterising the microstructural behaviour of superalloys.

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Follow this pinboard to discover the research within the field of photoluminescence

In 10 Seconds? Photoluminescence belongs to the family of luminescent materials - bodies that emit light due to an excitation. In this particular case, as the name suggests the excitation is photons. Over the past decade or so, they have found a dramatic rise in popularity due to LCD and plasma screens. However, ongoing research is looking at applications of carbon Nano-dots that exhibit photoluminescent properties.

Don’t believe it? Review the article ‘Carbon Nano-dots: Mechanisms of photoluminescence and principles of application’ – they discuss that potential applications lie within solar cells, bioimaging and sensors.

The science behind photoluminescence

As previously stated, the excitation source for photoluminescence is photons. Consequently, from absorbing the photons the pigment molecules within the material become excited and emit photons back out at a lower energy.

8 ITEMS PINNED

Nanoscale influence on photoluminescence and third order nonlinear susceptibility exhibited by ion-implanted Pt nanoparticles in Silica.

Abstract: The authors describe a systematic study about photoluminescence and third order nonlinear ultraviolet properties exhibited by platinum nanoparticles nucleated in a high-purity silica matrix. The modification in the characteristic photoluminescence spectra of the nanocomposites, range between 400 to 600 nm, was obtained by the assistance of a thermal annealing process that changed the average size of the platinum nanoparticles. The influence of temperature between 200-1100 °C during the thermal treatment of the nanostructures was analyzed. UV-VIS spectroscopy studies corroborated changes in the optical absorption resonances of the ion-implanted samples after annealing than can be correlated with the average size of the nanoparticles. The estimated averaged size was also corroborated by Transmision Electron Microscopy. For temperatures below 600 °C the system is mainly composed of ultra-small photoluminescent platinum nanoparticles. Larger platinum nanoparticles were formed at higher annealing temperatures but photoluminescence quenching was observed, as the typical plasmonics response of larger metal nanoparticles started to emerge. The photoluminescence emission for samples with particle size less than 2 nm is about 12 fold enhanced with respect to the samples with particle size in the range of 3-7 nm. Differences in the resulting photoluminescence spectra were revealed by substituting the participation of argon, hydrogen or nitrogen, as environmental gases for thermal annealing. A weak PL emission, featuring 1.5 nW at a laser excitation power of 800 µW, related to larger platinum nanoparticle was observed. New emission peaks emerging from the larger platinum nanoparticles were associated with a possible hydrogen adsorption on the nanoparticles surface. Third order nonlinear ultraviolet measurements were conducted by a time-resolved two-wave mixing method with self-diffraction at 355 nm wavelength. The observed self-diffraction decay time is less than 25 ps; regardless of the average size of the nanoparticles studied. The evolution of the self-diffracted intensities derived from temperature was also linked to nanoparticles mean size in the samples. Comparative two-wave mixing evaluations also validated a modification in third order nonlinear susceptibility exhibited by annealed samples. An important role of the Localized Surface Plasmon Resonance phenomena associated to the platinum nanoparticles for photoluminescence and optical nonlinearities was identified. A proposed hypothetical electronic mechanism that may explain the exceptional optical transitions related to low-dimensional platinum systems was discussed.

Pub.: 19 Apr '17, Pinned: 26 Apr '17

Programmable Colloidal Approach to Hierarchical Structures of Methylammonium Lead Bromide Perovskite Nanocrystals with Bright Photoluminescent Properties

Abstract: Systematic tailoring of nanocrystal architecture could provide unprecedented control over their electronic, photophysical, and charge transport properties for a variety of applications. However, at present, manipulation of the shape of perovskite nanocrystals is done mostly by trial-and-error-based experimental approaches. Here, we report systematic colloidal synthetic strategies to prepare methylammonium lead bromide quantum platelets and quantum cubes. In order to control the nucleation and growth processes of these nanocrystals, we appropriately manipulate the solvent system, surface ligand chemistry, and reaction temperature causing syntheses into anisotropic shapes. We demonstrate that both the presence of chlorinated solvent and a long chain aliphatic amine in the reaction mixture are crucial for the formation of ultrathin quantum platelets (∼2.5 nm in thickness), which is driven by mesoscale-assisted growth of spherical seed nanocrystals (∼1.6 nm in diameter) through attachment of monomers onto selective crystal facets. A combined surface and structural characterization, along with small-angle X-ray scattering analysis, confirm that the long hydrocarbon of the aliphatic amine is responsible for the well ordered hierarchical stacking of the quantum platelets of 3.5 nm separation. In contrast, the formation of ∼12 nm edge-length quantum cubes is a kinetically driven process in which a high flux of monomers is achieved by supplying thermal energy. The photoluminescence quantum yield of our quantum platelets (∼52%) is nearly 2-fold higher than quantum cubes. Moreover, the quantum platelets display a lower nonradiative rate constant than that found with quantum cubes, which suggests less surface trap states. Together, our research has the potential both to improve the design of synthetic methods for programmable control of shape and assembly and to provide insight into optoelectronic properties of these materials for solid-state device fabrication, e.g., light-emitting diodes, solar cells, and lasing materials.

Pub.: 05 Apr '17, Pinned: 26 Apr '17

A highly bioactive poly (amido amine)/70S30C bioactive glass hybrid with photoluminescent and antimicrobial properties for bone regeneration

Abstract: The field of tissue engineering constantly calls for novel biomaterials that possess intrinsically multifunctional properties such as bioactivity, bioimaging ability and antibacterial properties. In this paper, Poly (amido amine) generation 5/bioactive glass inorganic-organic hybrids have been developed through direct hybridization by 3-glycidoxypropyltrimethoxysilane (GPTMS) as coupling agent. Results indicated that the degree of covalent coupling by GPTMS and the weight percent of inorganic and organic constituents highly influence hybrids properties. It was found that nanoscale integration of inorganic and organic chains by GPTMS significantly endows hybrids with high thermal stability. Furthermore, hybrids exhibited photoluminescent ability (emission 400–600 nm and 700 nm) without incorporating of any organic dyes or quantum dots. In addition, hydrophilicity of our hybrids indicated good cell/material interaction. The biological apatite was formed on the surface of calcium containing hybrids when soaked in simulated body fluid (SBF) for 1 week. Hybrids also showed linear biodegradation behavior in SBF that could be controlled by the degree of covalent crosslinking which was indicative of their stable biodegradation ability. High inherent antibacterial properties against Staphylococcus aureus was also observed from poly (amido amine)/silica hybrids. No adverse cytotoxicity for human gingival fibroblast cell lines (HGF) was detected after 4 days. It is envisaged that our novel multifunctional hybrid system will confer intriguing potential in advancing the field of tissue engineering.

Pub.: 23 Apr '17, Pinned: 26 Apr '17