In situ observation of synthesized nanoparticles in ultra-dilute aerosols via X-ray scattering

In-air epitaxy of nanostructures (Aerotaxy) has recently emerged as a viable route for fast, large-scale production. In this study, we use small-angle X-ray scattering to perform direct in-flight characterizations of the first step of this process, i.e., the engineered formation of Au and Pt aerosol nanoparticles by spark generation in a flow of N₂ gas. This represents a particular challenge for characterization because the particle density can be extremely low in controlled production. The particles produced are examined during production at operational pressures close to atmospheric conditions and exhibit a lognormal size distribution ranging from 5–100 nm. The Au and Pt particle production and detection are compared. We observe and characterize the nanoparticles at different stages of synthesis and extract the corresponding dominant physical properties, including the average particle diameter and sphericity, as influenced by particle sintering and the presence of aggregates. We observe highly sorted and sintered spherical Au nanoparticles at ultra-dilute concentrations (< 5 × 10⁵ particles/cm³) corresponding to a volume fraction below 3 × 10^–10, which is orders of magnitude below that of previously measured aerosols. We independently confirm an average particle radius of 25 nm via Guinier and Kratky plot analysis. Our study indicates that with high-intensity synchrotron beams and careful consideration of background removal, size and shape information can be obtained for extremely low particle concentrations with industrially relevant narrow size distributions.

     

Distribution-free uncertainty quantification for kernel methods by gradient perturbations

Machine Learning - We propose a data-driven approach to quantify the uncertainty of models constructed by kernel methods. Our approach minimizes the needed distributional assumptions, hence,...     

High-Alumina Mixes Based on Molded Bauxite Suspensions

Refractories and Industrial Ceramics - Results of studying the rheotechnological properties of moldable refractory mixes based on bauxite suspensions plasticized with refractory clay are presented....     

Results from Survey and Geotechnical Monitoring on Test Site No. 3 of the Zagorsk PSP-2

Power Technology and Engineering - The major results from the survey and geotechnical monitoring during the leveling of the model foundation of the Zagorsk PSP-2 in test site No. 3 are presented....     

Concerning the Data of Numerical and Physical Experiments in Studying the Adsorption of Gas and Vapors in Micropores of Active Carbons

Protection of Metals and Physical Chemistry of Surfaces - The conditions for carrying out molecular dynamics calculations of adsorption isotherms of gases and vapors in micropores of active carbons...