Analysis of the atomic structure of CdS magic-size clusters by X-ray absorption spectroscopy

Abstract

A methodology to construct atomistic models of magic-size clusters from X-ray absorption spectroscopy for subsequent simulations and in-depth analysis.

Quantifying intuition: Bayesian approach to figures of merit in EXAFS analysis of magic size clusters

“…The result is almost identical for DFT-based optimisation with ZB structure coming slightly on top in the ranking. For MSC 322 the results show the β-Sn-like structure being ranked the highest in both UFF and DFT cases (this is consistent with the results of our recent work 6 ). We can also conclude, that both UFF and DFT-based geometry optimisations, although show small quantitative differences in model ranking, ultimately yield very similar results.…”

“…These MSCs exhibit a sharp UV-vis absorption peak at 311 nm (MSC 311) but when heated to 60 °C (ref. 4) this peak shifts to 322 nm (MSC 322) 6 and the shift is accompanied by atomic structure rearrangement as indicated by X-ray pair distribution function (xPDF) and XAS analysis. 5,6 Due to their small size leading to the lack of long-range order, establishing the atomic-level structure of MSCs is challenging 41 and in this work we examine the sensitivity of our new EXAFS BFI-based FoM to the structural model selection.…”

Semiconductor Quantum Dots as Target Analytes: Properties, Surface Chemistry and Detection

“…An analysis of the nearest coordination shells around a photoabsorber can be performed using conventional methods of analysis to determine the local structure parameters and degree of disorder. The combination of XANES and EXAFS analyses has proved to be a robust methodology for the characterisation of complex systems [ 164 , 165 ], even when only EXAFS measurements are obtained and XANES spectra are used only for comparison purposes [ 166 , 167 ]. This approach can provide both local symmetry information (through XANES), as well as structural and stoichiometry information (through EXAFS), which can be used as an input for the subsequent analysis of scattering data and computer modelling [ 165 ] or as a support to density functional theoretical (DFT) calculations [ 168 ].…”

Temperature Dependence of the CdS Bandgap in the Extreme Confinement Regime

“…In this study, the wurtzite Cd 37 S 20 cluster structure is utilized, which is widely accepted as one of the most representative models for these clusters. ,− To simplify the model, we used acetate ions to represent the experimental oleate ligands. Excess ligands were initially placed near the semiconductor core to replicate the ligand-rich environment of the experiments, followed by geometry optimization using DFT with the PBE functional .…”