Search results for "Photoluminescence"

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.

Photoluminescence and Electron Spin Resonance of Silicon Dioxide Crystal with Rutile Structure (Stishovite)

2018

This work was supported by ERANET MYND. Also, financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ/2017/2 realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. The authors express our gratitude to R.I. Mashkovtsev for help in ESR signal interpretation. The authors are appreciative to T.I. Dyuzheva, L.M. Lityagina, N.A. Bendeliani for stishovite single crystals and to K. Hubner and H.-J. Fitting for stishovite powder of Barringer Meteor Crater.

Tuning of Emission Wavelength of CaS:Eu by Addition of Oxygen Using Atomic Layer Deposition

2021

| openaire: EC/H2020/820423/EU//S2QUIP | openaire: EC/H2020/834742/EU//ATOP | openaire: EC/H2020/965124/EU//FEMTOCHIP Atomic layer deposition (ALD) technology has unlocked new ways of manipulating the growth of inorganic materials. The fine control at the atomic level allowed by ALD technology creates the perfect conditions for the inclusion of new cationic or anionic elements of the already-known materials. Consequently, novel material characteristics may arise with new functions for applications. This is especially relevant for inorganic luminescent materials where slight changes in the vicinity of the luminescent centers may originate new emission properties. Here, we studied the lumines…

Ag44(EBT)26(TPP)4 Nanoclusters with Tailored Molecular and Electronic Structure

2021

Although atomically precise metalloid nanoclusters (NCs) of identical size with distinctly different molecular structures are highly desirable to understand the structural effects on the intriguing optical and photophysical properties, their synthesis remains highly challenging. Herein, we employed phosphine and thiol capping ligands featuring appropriate steric effects and synthesized a charge‐neutral Ag NC with the formula, Ag 44 (EBT) 26 (TPP) 4 (EBT: 2‐ethylbenzenethiolate; TPP: triphenylphosphine). The single‐crystal X‐ray structure reveals that this NC has a hollow metal core of Ag 12 @Ag 20 and a metal‐ligand shell of Ag 12 (EBT) 26 (TPP) 4 . The presence of mixed ligands and long V‐…

UV-VISIBLE LUMINESCENCE OF SILICA NANOPARTICLES

Understanding the White-Emitting CaMoO4 Co-Doped Eu3+, Tb3+, and Tm3+ Phosphor through Experiment and Computation

2019

In this article, the synthesis by means of the spray pyrolysis method, of the CaMoO4 and rare-earth cation (RE3+)-doped CaMoO4:xRE3+ (RE3+ = Eu3+, Tb3+, and Tm3+; and x = 1, 2, and 4% mol) compounds, is presented. The as-synthesized samples were characterized using X-ray diffraction, Rietveld refinement, field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and photoluminescence (PL) spectroscopy. To complement and rationalize the experimental results, first-principles calculations, at the density functional theory level, have been performed to analyze the band structure and density of states. In addition, a theoretical method based on the calculations of surface energie…

Formation of Si/SiO2 Luminescent Quantum Dots From Mesoporous Silicon by Sodium Tetraborate/Citric Acid Oxidation Treatment

2019

We propose a rapid, one-pot method to generate photoluminescent (PL) mesoporous silicon nanoparticles (PSiNPs). Typically, mesoporous silicon (meso-PSi) films, obtained by electrochemical etching of monocrystalline silicon substrates, do not display strong PL because the silicon nanocrystals (nc-Si) in the skeleton are generally too large to display quantum confinement effects. Here we describe an improved approach to form photoluminescent PSiNPs from meso-PSi by partial oxidation in aqueous sodium borate (borax) solutions. The borax solution acts to simultaneously oxidize the nc-Si surface and to partially dissolve the oxide product. This results in reduction of the size of the nc-Si core …

Pressure-Dependent Tuning of Photoluminescence and Size Distribution of Carbon Nanodots for Theranostic Anticancer Applications

2020

Carbon nanodots (CDs) have recently attracted attention in the field of nanomedicine because of the biocompatibility, cost-effective nature, high specific surface, good near infrared (NIR) photothermal conversion into heat and tunable fluorescence properties, which have paved the way toward incorporating use of CDs into innovative anticancer theranostic platforms. However, a reliable synthesis of CDs with established and controlled physiochemical proprieties is precluded owing to the lack of full manipulation of thermodynamic parameters during the synthesis, thus limiting their use in real world medical applications. Herein, we developed a robust solvothermal protocol which allow fine contr…

Effect of thermal annealing on the luminescence of defective ZnO nanoparticles synthesized by pulsed laser ablation in water

2016

This work concerns ZnO nanoparticles (NPs), with sizes of tens of nm, produced by ablation with a pulsed Nd:YAG laser of a Zn plate in H2O. TEM images evidence the formation of nanoparticles with sizes of tens of nm. Moreover, HRTEM images and Raman spectra show that the distance between the crystalline planes and the vibrational modes are consistent with ZnO nanocrystal in wurtzite structure. Their optical properties are characterized by two emission bands both excited above the energy gap (3.4 eV): the first at 3.3 eV is associated with excitons recombination, the second at 2.2 eV is proposed to originate from a singly ionized oxygen vacancy. The green emission is independent of water pH,…

Gold Au(I)6 Clusters with Ligand-Derived Atomic Steric Locking: Multifunctional Optoelectrical Properties and Quantum Coherence

2023

Funding Information: This work was supported by the ERC Advanced grant (DRIVEN, ERC‐2016‐AdG‐742829), the ERC grant (834742), the EU H2020‐MSCA‐RISE‐872049 (IPN‐Bio), the Academy of Finland's Centre of Excellence in Molecular Engineering of Biosynthetic Hybrid Materials Research (HYBER, 2014–2019), and Life‐Inspired Hybrid Materials (LIBER, 346108), Academy of Finland project fundings (No. 352900, 314810, 333982, 336144, 352780, 352930 and 353364), FinnCERES and Photonics Research and Innovation (PREIN) flagship programs. The authors acknowledge the provision of facilities and technical support by Aalto University OtaNano – Nanomicroscopy Center (Aalto‐NMC). | openaire: EC/H2020/834742/EU//…