Optical properties of directly excited erbium $\left({\text{Er}}^{3+}\right)$ ions have been studied in silicon rich silicon oxide materials codoped with ${\text{Er}}^{3+}$ . The spectral dependence of the direct excitation cross section $\left({\sigma }_{\text{dir}}\right)$ of the ${\text{Er}}^{3+}$ atomic ${{}^{4}I}_{15/2}\to {{}^{4}I}_{11/2}$ transition (around $0.98\mu \text{m}$ ) has been measured by time resolved $\mu$ -photoluminescence measurements. We have determined that ${\sigma }_{\text{dir}}$ is $9.0\pm 1.5\times {10}^{-21}{\text{cm}}^2$ at 983 nm, at least twice larger than the value determined on a stoichiometric ${\text{SiO}}_2$ matrix. This result, in combination with a measurement of the population of excited ${\text{Er}}^{3+}$ as a function of the pumping flux, has allowed quantifying accurately the amount of optically active ${\text{Er}}^{3+}$ . This concentration is, in the best of the cases, 26% of the total Er population measured by secondary ion mass spectrometry, which means that only this percentage could provide optical gain in an eventual optical amplifier based on this material.

The temperature and chemical dependence of the melt viscosity are ubiquitous in the model development of the volcanic dynamics, as well as in the glass production and design. We focussed on the yet-explored relationship between the bulk and shear moduli ratio and boson peak with the melt fragility of their parental glasses. Here, we explored the extension of the observed trend by testing the conventional binary system Na₂O-SiO₂, thus providing new evidence supporting the link between the flow of melts and supercooled liquids and the vibrational dynamics of their parental glasses. This was accomplished by integrating new low-frequency Raman measurements and integrating data from the literature on Brillouin light scattering and viscometry. This approach allows us to feed the MYEGA equation with reliable input parameters to quantitatively predict the viscosity of the Na₂O-SiO₂ system from the liquid up to the glass transition.

X-ray absorption measurements in total electron yield mode have been carried out on Si nanodots embedded in amorphous silica produced by plasma enhanced chemical vapor deposition (PECVD). The amount of Si atoms composing the Si nanodots and the chemical composition of the amorphous host matrix has been determined thanks to the comparison with Rutherford backscattering spectrometry data. The influence of nitrogen, incorporated during the PECVD procedure, on the structure of the host silica matrix has been discussed.

Porous silicon (pSi), a sponge-like material, was coated by ALD with a TiO ₂ layer to stabilize photoluminescence in biological media. In vitro results open the way to promising applications in nanomedicine.

Over the last decade, the CO₂ reduction reaction (CO₂RR) has been increasingly exploited for the synthesis of high‐value raw materials in gaseous or liquid form, although no examples of CO₂ fixation in nanoparticle systems have been demonstrated. Herein, CO₂ fixation into solid nanomaterials by laser synthesis and processing of gold colloids in water, traditionally considered a green approach leading to ligand‐free nanoparticles without the formation of by‐products, is reported. If carbon monoxide‐rich gold nanoparticles are observable even after synthesis in deionized water, the presence of CO₂ derivatives in alkaline water environment leads to C₂ and C₃ coupling with the production of carboxylic acids as a typical CO₂RR fingerprint. While laser processing of preformed gold colloids is selective for C₂ coupling, both C₂ and C₃ coupling to lactic acid are observed during pulsed laser ablation of a gold target. In the latter case, it is demonstrated that it is possible to synthesize photoluminescent organometallic nanocomposites in the blue spectral region with a quantum yield of about 20% under adequate experimental conditions. In this research, new pathways are offered to be explored in energetics, photonics, catalysis, and synthesis at the nanoscale.