X-ray Absorption Spectroscopy as Process Analytical Technology: Reaction Studies for the Manufacture of Sulfonate-Stabilized Calcium Carbonate Particles

Process analytical technologies are widely used to inform process control by identifying relationships between reagents and products. Here, we present a novel process analytical technology system for operando XAS on multiphase multicomponent synthesis processes based on the combination of a conventional lab-scale agitated reactor with a liquid-jet cell. The preparation of sulfonate-stabilized CaCO3 particles from polyphasic Ca(OH)2 dispersions was monitored in real time by Ca K-edge XAS to identify changes in Ca speciation in the bulk solution/dispersion as a function of time and process conditions. Linear combination fitting of the spectra quantitatively resolved composition changes from the initial conversion of Ca(OH)2 to the Ca(R–SO3)2 surfactant to the ultimate formation of nCaCO3·mCa(R− SO3)2 particles. The system provides a novel tool with strong chemical specificity for probing multiphase synthesis processes at a molecular level, providing an avenue to establishing the relationships between critical quality attributes of a process and the quality and performance of the product

Structural, Spectroscopic, and Excitonic Dynamic Characterization in Atomically Thin Yb3+‐Doped MoS2, Fabricated by Femtosecond Pulsed Laser Deposition

The large area deposition and synthesis of 10 mm × 10 mm atomically thin Yb³⁺‐doped MoS₂ films by femtosecond pulsed laser deposition on a silica glass optical platform for device applications are demonstrated for the first time. The presence of Yb³⁺‐ion doping is confirmed using photoluminescence (PL), X‐ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The Yb³⁺‐doped MoS₂ films, when excited with a 976 nm laser, exhibit room temperature PL with a peak at 1002 nm. The XPS and Raman spectroscopic analyses of the Yb³⁺‐doped and undoped films show that the deposited films are a mixture of 2H‐ and 1T‐MoS₂ after postdeposition annealing at 500 °C. The density functional theory analysis shows that the 1T phase is metastable by +77 kJ (≈0.8 eV) mol‐1, when compared with the 2H state at 0 K. Ultrafast transient nonlinear optical spectroscopic measurements prove that the saturable absorption of undoped MoS₂ is significantly modified after Yb³⁺‐ion doping, by displaying dopant‐host structure charge transfer. The complex transient absorption line shape shows a combination of bleach (negative) signals at the A (670 nm) and B (630 nm) exciton energies, and a strong induced absorption below the A exciton level. The results presented herein provide critical insight in designing novel rare‐earth‐ion doped 2D materials and devices

Augmentation de l'incidence de la tuberculose dans un Centre Hospitalier périphérique de Lyon entre 2001 et 2006

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF