A multiple ion cluster source is a fabrication technique based on the ion-spattering of a target material, which is placed into a vacuum chamber. The sputtered atoms aggregate forming nanoparticles in the gas phase that can be collected on arbitrary surfaces (soft landing) for different uses. In the case of a multiple ion-cluster source, up to three different elements can be combined to form nanoparticles with different structure.
Our infrastructure includes a scaled up multiple ion cluster source to have larger production rates and an ultra-high vacuum (UHV) environment to ensure high purity (no-capping), controlled size (can be tuned from 5 nm to 20 nm) and stoichiometry (e.g., different oxides can be made). This machine combines three different targets and allows to include gases in the reaction zone, in such a way that nanoparticles comprising up to three elements can be designed with complex architectures (core-shell, core-shell-shell, alloys, oxides…) and collected, with high throughput, on arbitrary surfaces. Substrates where nanoparticles are collected can be up to 80 mm x 20 mm. For smaller samples (typically 10 mm x 10 mm) it is possible to investigate the nanoparticles’ properties in-situ, e.g, catalytic activity. To this aim, the substrate can be annealed in UHV up 700ºC and the nanoparticles can be in-situ characterized by XPS, UPS, Auger, thermal desorption and Infrared spectroscopy. Moreover, formed nanoparticles can be annealed in-flight (i.e. in the gas phase, before landing) to achieve metastable atomic structures. These nanoparticles can be of interest for a large number of researchers requiring new materials for energy, health, optical or magnetic applications. In principle, all materials that can be sputtered (either DC or RF) can be used as source of nanoparticle elements. [Martinez et al. Sci. Rep. 8, 7250 (2018)]
XPS is a surface spectroscopic technique for quantitative measurements of the elemental composition or stoichiometry and the chemical state of the present elements, like their oxidation state and chemical bonds. XPS is highly surface sensitive, giving chemical and binding energy information from the a narrow region close to the surface.
IR spectroscopy is based on the absorption of infrared radiation by matter. This leads to energetic transitions in the vibrational state of concrete chemical bonds. Since the frequencies that are absorbed by the molecules are characteristic of their structure, this technique is a powerful tool for qualitative and quantitative molecular analysis.
VUV/UV/Vis/NIR spectroscopy is the measurement of the attenuation of a beam of light after it passes through a sample or after reflection from a sample surface. It is useful to characterize absorption, transmission, and reflectivity of a variety of technologically important materials, such as gases, film, pigments, coatings, windows, and filters.
XAS is sensitive to the local bonding environment of the atom absorbing the X-rays, providing information on oxidation states, local orbital symmetry, molecular orientation and chemically selective density of states. It is widely used in molecular and condensed matter physics, material science, engineering, chemistry, earth science and biology.
Ultraviolet photoelectron spectroscopy (UPS), also described as photoemission spectroscopy (PES) if applied to measurements on solid surfaces, is suitable for measuring spectral features close to the Fermi level for surfaces or adsorbates, and particularly useful for determining work function and electronic properties of valence band of a material.
