Redox and Organic Post-Annealing Chemical Processes Impacting the Fluorescence of N V - Centers into Nanodiamonds : A Competitive Process Between Exfoliation and Functionalisation.

Among the several aspects involved into the synthesis of monocharged nitrogene-vacancy N V - colored centers produced into nanodiamonds ND, the post-annealing cleaning process, such as sulfo-nitric acid cleaning or thermal oxidation under acid conditions, can be seen as a factor impacting the optical response of these N V - colored centers. A significative difference of optical response is in fact noticed modifying the post-annealing treatment conditions, between a pure oxidative treatment at room temperature and a mixed-process including oxidation and thermal activation. Specific chemical processes and surface chemical aspects are proposed to explain the optical signals obtained by fluorescence. Some chemical pathways are then found more efficient than others to limit the fluorescence quenching of these colored N V - emitters.

Picosecond pulse radiolysis of the liquid diethyl carbonate.

The diethyl carbonate, DEC, is an ester that is used as a solvent in Li-ion batteries, but its behavior under ionizing radiation was unknown. The transient optical absorption spectra, the decay kinetics, and the influence of various scavengers have been studied by using the picosecond laser-triggered electron accelerator ELYSE. In neat DEC, the intense near-IR (NIR) absorption spectrum is assigned to the solvated electron. It is overlapped in the visible range by another transient but longer-lived and less intense band that is assigned to the oxidized radical DEC(-H). The solvated electron molar absorption coefficients and radiolytic yield evolution from 25 ps, the geminate recombination kinetics, and the rate constants of electron transfer reactions to scavengers are determined. The radiolytic mechanism, indicating a certain radioresistance of DEC, is compared with that for other solvents.

Impact of the concentration in polymer on the dynamic behavior of Polymer Stabilized Ferroelectric Liquid Crystal using Snap-shot Mueller Matrix Polarimetry.

Experimental results are presented related to the dynamic behaviour of Polymer Stabilized Ferro-electric Liquid Crystal (PSFLC) samples under external applied electric field, using Snap-shot Mueller Matrix Polarimetry (SMMP) and Mueller Matrix (MM) formalism. Different polarimetric coefficients are simultaneously extracted from each channeled spectrum measured with this full-optical SMMP technique. The impact of the concentration of polymer present into the liquid crystal cell on this dynamic behaviour is studied, permitting a direct and quick characterisation of the material. The results obtained for PSFLC are compared with those already measured for pure Surface Stabilized Ferro-electric Liquid Crystal (SSFLC) samples, which correspond to a 0% concentration in polymer.

Mueller matrix polarimetry for improved liver fibrosis diagnosis.

An experimental Mueller matrix polarimeter is used to quantify human liver fibrosis by measuring retardance and depolarization of thin biopsies. The former parameter is sensitive to fibrillar collagen, the latter is specifically sensitive to fibrillar collagen around blood vessels, which is not significant for liver fibrosis diagnosis. By using depolarization like a filter, retardance distribution enables distinguishing between disease stages and limits the high degree of observer discrepancy.

Jones matrix formalism for the theory of picosecond shear acoustic pulse detection.

A theoretical analysis of the transient optical reflectivity of a sample by a normalized Jones matrix is presented. The off-diagonal components of the normalized matrix are identified with the complex rotation of the polarization ellipse. Transient optical polarimetry is a relevant technique to detect shear acoustic strain pulses propagating normally to the surface of an optically isotropic sample. Moreover, polarimetry has a selective sensitivity to shear waves, as this technique cannot detect longitudinal waves that propagate normally to the sample surface.