We present results on the photoluminescence (PL) properties of silicon nanocrystals as a function their size. The are synthesized by laser pyrolysis silane in gas flow reactor and deposited at low energy substrate after mechanical velocity size selection. Both spectroscopy yield have been studied well effect aging samples air. measurements show that PL nanocrystallites follows quantum confinement model very closely. apparent yields rather high (up to 18%). From evaluation distribution...

Silicon nanocrystals with diameters between 2.5 and 8 nm were prepared by pulsed CO2 laser pyrolysis of silane in a gas flow reactor expanded through conical nozzle into high vacuum. Using fast-spinning molecular-beam chopper, they size-selectively deposited on dedicated quartz substrates. Finally, the photoluminescence silicon their yield measured as function size. It was found that follows very closely quantum-confinement model. The shows pronounced maximum for sizes 3 4 nm.

Doubly luminescent core/shell structure nanoparticles were synthesized for biological detection. In the first step gadolinium oxide (Gd2O3) core doped with Tb3+ ions was obtained by applying, modifications, polyol route, which allows direct precipitation of in a polyalcohol medium. The presence Gd2O3 crystalline matrix confers attractive optical properties long-term studies and multilabeling such as high photostability narrow emission bands. water sensitivity these particles, is detrimental...

This work examines the initial growth and collapse stages of bubbles induced by laser ablation in liquids. First, bubble shape size are tracked using an ultrafast camera a shadowgraph imaging setup. The use ensures high control reproducibility, because thorough measurement each lifetime is performed. Next, analytical cavitation-based model developed to assess thermodynamic properties. study demonstrates that evolution adiabatic driven inertial forces. Surprisingly, it found consist...

Pulsed laser ablation has proved its reliability for the synthesis of nano-particles and nano-structured materials, including metastable phases complex stoichiometries. The possible nucleation nanoparticles in gas phase their growth been little investigated, due to difficulty following composition as well thermodynamic parameters. We show that such information can be obtained from optically active plasma during short lifetime, only a few microseconds each pulse, result quick quenching liquid...

Tb2O3 coated with a polysiloxane layer is biocompatible nanoscintillator that exhibits an appropriate pattern of biodistribution after injection. In this contribution, we combine nanosystem porphyrin molecules are able to generate singlet oxygen, major cytotoxic agent for photodynamic therapy application. Using time-resolved laser spectroscopy and oxygen probes, demonstrate combination suitable generation induced by X-ray provide physical study the energy transfer observed between porphyrin....

Abstract In this study, a reversible pressure‐sensing material with high sensitivity is presented. Mixed β‐diketonate complexes of Tb 3+ and Eu [(Ln)(acac) 3 phen] are synthesized phenanthroline as an ancillary ligand. The organic ligands provide the antenna effect to make Ln complex excitable at 405 nm. emission results from efficient energy transfer (ET) . Under nm excitation, intensity decreases whereas increases pressure, making potential pressure sensor based on...

Since the discovery of small diamond grains in meteorites, presence such interstellar medium has been suspected. Here we report what think to be first unambiguous evidence crystallites dusty envelopes surrounding stars. Thanks experimental results obtained different laboratories on growth process, identify two peculiar unidentified infrared emission bands at 3.43 and 3.53 μm as vibrational modes hydrogen-terminated crystalline facets diamond. The intensities these strong features observed...

The main objective of this contribution is to point out the potentialities cerium doped LuAG single crystal as pixels and fibers. We first show that after optimization growth conditions using Bridgman technology, composition exhibits very good performances for scintillating applications (up 26 000 photons/MeV). When grown with micropulling down fiber shapes can be obtained while intrinsic are preserved. For future high energy experiments requiring new detector concepts capable delivering...

To evaluate the efficiency of photodynamic effect induced by X-rays, we quantified fraction energy deposited in nanoscintillators after interactions with X or γ-rays, introducing <italic>η</italic>_nano as a new loss parameter.

Abstract Crystalline Si nanoparticles with diameters between 2.5 and 20 nm are prepared by CO 2 ‐laser‐induced decomposition of silane in a gas flow reactor. A small portion the products created reaction zone is extracted through nozzle into high‐acuum apparatus to form freely propagating molecular beam clusters that can be deposited on suitable substrates. The strong visible photoluminescence (PL) nanocrystals studied as function their size, time for which they exposed air. All observations...

Silicon nanocrystals were prepared by laser pyrolysis of silane in a gas flow reactor and deposited on substrates cluster beam deposition. The evolution the photoluminescence was measured as function time samples exposed to air. With gradual air exposure oxidation, increases intensity its peak wavelength shifts blue. At same time, band becomes wider. To remove oxide layer, hydrofluoric acid (HF) vapor. HF attack has no influence position but leads smaller width. observations can be explained...

Samples of silicon nanocrystals on various substrates were prepared by cluster beam deposition nanoparticles, obtained laser-induced pyrolysis silane in a flow reactor. Using optical ellipsometry, the properties (refractive index and extinction coefficient) as-prepared nanocrystal layers determined wavelength range from 240 to 700 nm. Two dispersion models used describe properties: Bruggeman effective medium approximation model Tauc–Lorentz model. The study showed that while simple could not...

The origin of the multiexponential photoluminescence (PL) decay Si quantum dots (QDs) has been debated for a long time. We present studies combining time-resolved PL experiments and tight binding calculations phonon-assisted optical transitions showing that distribution lifetimes its wavelength dependence are quantitatively predictable can be interpreted as intrinsic properties QDs due to indirect nature bandgap. This result generalized QD ensembles any gap semiconductor.

This contribution is a review of the luminescence and scintillation properties nanoparticles (NP), particularly doped insulators. Luminescence spectroscopy an appropriate tool to probe matter at nanoscale. also last stage process. Specific surface structural effects occurring in NP are reported. Their consequences on discussed. Parts related preparation method. On other hand some intrinsic nanostructures which can modify optical described: quantum confinement dielectric confinement. The...

We performed laser ablation of doped oxides, Y2O3:Eu3+, Gd2O3:Eu3+, and Y3Al5O12:Ce3+ (YAG:Ce), in an aqueous solution 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (MEEAA). Nanoparticles are produced characterized using electron microscopy luminescence spectroscopy. show that the polyether chain ensures stabilization objects formed medium while complexing group limits their size sharpens distribution. The nanoparticles from sesquioxide targets a "cubic disordered" phase as expected for very...

We investigate the origin of band at 3.31 eV (A band) commonly observed in emission spectra various ZnO samples. This is prime importance for confirmation $p$ doping nanostructures. check validity three main hypotheses generally evoked to explain it undoped ZnO, namely, surface states, 1LO phonon replica free exciton and a defect-related transition. Using samples structured different scales, from macro nano through meso (i.e., single crystal, nanoparticles assembly, microcrystalline pellet),...

New barium–organic derivatives are introduced as countercations in the iodocuprates and -argentates to yield novel hybrids with unique structural motifs bonding modes, many of them also showing vivid fluorescence on exposure UV light. The tetrahedral MX4/trigonal-coplanar MX3 unit these [Ba2(DMSO)12Cu8I12] (1) [Ba(tetraglyme)2]2[Ag8I12]·EtOH (7) can be replaced by M′I4/M′I3 without compromising their basic motifs, thus leading formation rare mixed Cu–Ag iodometalates [Ba2(DMSO)12Cu4Ag4I12]...

The first structure elucidation of a lamellar gold thiolate coordination polymer is described. [Au(p-SPhCO2Me)]n obtained from the simultaneous esterification mercaptobenzoic acid and reduction Au(iii) precursor. Despite presence aurophilic interactions, intense phosphorescence (QY ∼ 70%) originates intra-ligand metal-to-ligand transitions.

Obtaining transparent glasses made of functional coordination polymers (CPs) represents a tremendous opportunity for optical applications. In this context, the first and red-emissive gold thiolate CPs have been obtained by simply applying mechanical pressure to amorphous powders CPs. The three gold-based CP are composed either thiophenolate [Au(SPh)] n , phenylmethanethiolate [Au(SMePh)] or phenylethanethiolate [Au(SEtPh)] . presence longer alkyl chain between phenyl ring led formation glass...