Trends in anomalous small-angle X-ray scattering in grazing incidence for supported nanoalloyed and core-shell metallic nanoparticles

Abstract

Abstract. As atomic structure and morphology of particles are directly correlated to their functional properties, experimental methods probing local and average features of particles at the nanoscale elicit a growing interest. Anomalous small-angle X-ray scattering (ASAXS) is a very attractive technique to investigate the size, shape and spatial distribution of nanoobjects embedded in a homogeneous matrix or in porous media. The anomalous variation of the scattering factor close to an absorption edge enables element specific investigations. In the case of supported nano-objects, the use of grazing incidence is necessary to limit the probed depth. The combination of grazing incidence with the anomalous technique provides a powerful new method, anomalous grazing incidence small-angle X-ray scattering (AGISAXS), to disentangle complex chemical patterns in supported multi-component nano-structures. Nevertheless, a proper data analysis requires accurate quantitative measurements associated to an adapted theoretical framework. This paper presents anomalous methods applied to nanoalloys phase separation in the 1-10 nm size range, and focuses on the application of AGISAXS in bimetallic systems: nanocomposite films and core-shell supported nanoparticles.

Ru-core/Cu-shell bimetallic nanoparticles with controlled size formed in one-pot synthesis

“…18 Therefore, the differential intensity, ΔI NP (q) = I NP (q, E 1 ) − I NP (q, E 2 ), is only dependent on S RuRu (q) and S RuCu (q) and its behaviour with q provides interesting information. 19 Fig. 4(a-c) show the total intensities I NP (q) measured at 22.1 keV for the three Cu atomic fractions together with their corresponding differential intensities calculated between 21.6 and 22.1 keV after rescaling.…”

“…Based on the ASAXS extracted parameters and the proposed mechanism of RuCuNPs formation relying on the rapid 19 3.4 ± 0.8 nucleation of Ru followed by the agglomeration of Cu on the Ru cores, the mean size and concentration of the bimetallic NPs can be estimated using a rather simple structural description. Let us assume that the metallic NPs adopt a nested icosahedral structure.…”

Determination of the electronic and structural configuration of coordination compounds by synchrotron-radiation techniques

“…These improvements have recently enabled, for several favourable cases, applications of the technique also to powdered samples [229,547,548] and short-range ordered systems (e.g. anomalous SAXS, ASAXS [521,549,550] and anomalous WAXS, AWAXS [313]). The idea of exploiting anomalous scattering (in particular the phase-shift term Δf ") to elegantly solve the phase problem in crystallography, was firstly proposed by Bijvoet, in an article dating back to 1949 [551].…”

Anomalous grazing-incidence small-angle X-ray scattering of Ga2O3-based nanoparticles

“…According to the specific constituents, the scattering experiments are performed at K or L edges of the considered elements. The variations of the scattering factor are usually from a few percent for K edges up to 20% in the best cases for L edges (Andreazza et al, 2012). Below 2 keV, the scattering technique called resonant soft X-ray scattering can access K edges of elements up to Si (Z = 14) and L edges of elements up to Sr (Z = 38).…”