We present a detailed experimental investigation of the carrier recombination dynamics in CsPbBr 3 films by means of picosecond time-resolved photoluminescence. Temperaturedependent measurements show that carrier capture and release from the nanocrystals (NCs) surfaces determine the observed increase of the recombination lifetime with the increase of temperature. This result opens the way to probe the surface of the NCs, which is of the utmost relevance for optoelectronic applications, and to eventually give feedback for surface treatments of NCs.

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The role of phosphate additives on the hydration process of magnesium silicate cement pastes was investigated through a multi-technique approach. A MgO/SiO 2 mixture was hydrated for 28 days either in the absence or in the presence of sodium hexametaphosphate, trimetaphosphate or orthophosphate. Information on the kinetics of the hydration reaction was acquired by monitoring the free water index by means of differential scanning calorimetry, while the hydration products were thoroughly investigated by X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and 29 Si solid-state nuclear magnetic resonance spectroscopy. The overall results provide new insight into the effect of phosphates on the hydration reaction and on the structure of magnesium silicate hydrate cements. All additives showed a plasticizing effect and promoted the formation of the binding phase magnesium silicate hydrate (M-S-H), without significantly altering its structure. Sodium orthophosphate was found to be by far the bestperforming additive, even better than sodium hexametaphosphate, which is commonly used in these cementitious formulations. For the first time, 31 P solid-state NMR investigation allowed orthophosphate ion to be identified as the effective species. Keywords Magnesium silicate hydrate Á Orthophosphate Á Plasticizer Á Hydration kinetics Á Thermal analysis Á MAS NMR A1 Monica Tonelli and Francesca Martini have contributed A2 equally to this work.

The stabilization of the optical properties of anisotropic plasmonic particles upon thermal annealing and laser irradiation is an important issue in many biomedical applications. Here, we address the effect of small thiols on the thermal and photostability of gold nanorods. As-synthesized colloids were treated with mixtures of thiolated polyethylene glycol and methylbenzenethiol with molar ratios ranging from 0, for pure PEG, to 20 and then incubated in an oven at sub-boiling conditions. We found that small thiols dramatically enhance the thermal stability of gold nanorods. For instance, after 1 h at 90 °C samples with pure PEG lost more than 70% of optical absorbance at their initial peak position, while particles coated with a thicker layer of methylbenzenethiol remained nearly unchanged. We ascribe this effect to a modulation of the activation barrier for surface diffusion of gold atoms. Additionally, we addressed the translation of this effect to the photostability of gold nanorods irradiated under conditions of interest in photoacoustic imaging and found that small thiols delay relevant damage thresholds by as much as a factor of 2. Our findings will help researchers design novel tags that overcome the limitations related to thermal and photoinstabilities in a broad variety of applicative contexts.