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Analysis of the atomic structure of CdS magic-size clusters by X-ray absorption spectroscopy
Authors:
Ying
Liu
(Diamond Light Source)
,
Lei
Tan
(Queen Mary University of London)
,
Giannantonio
Cibin
(Diamond Light Source)
,
Diego
Gianolio
(Diamond Light Source)
,
Shuo
Han
(Sichuan University)
,
Kui
Yu
(Sichuan University)
,
Martin T.
Dove
(Queen Mary University of London; Wuhan University of Technology; Sichuan University)
,
Andrei
Sapelkin
(Queen Mary University of London)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
Nanoscale
, VOL 34
State:
Published (Approved)
Published:
September 2020

Abstract: Magic-size clusters are ultra-small colloidal semiconductor systems that are intensively studied due to their monodisperse nature and sharp UV-vis absorption peak compared with regular quantum dots. However, the small size of such clusters (<2 nm), and the large surface-to-bulk ratio significantly limit characterisation techniques that can be utilised. Here we demonstrate how a combination of EXAFS and XANES analyses can be used to obtain information about sample stoichiometry and cluster symmetry. Investigating two types of clusters that show sharp UV-vis absorption peaks at 311 nm and 322 nm, we found that both samples possess approximately 2[thin space (1/6-em)]:[thin space (1/6-em)]1 Cd[thin space (1/6-em)]:[thin space (1/6-em)]S ratio and have similar nearest-neighbour structural arrangements. However, both samples demonstrate a significant departure from the tetrahedral structural arrangement, with an average bond angle determined to be around 106.1° showing a bi-fold bond angle distribution. Our results suggest that both samples are quasi-isomers – their core structures have identical chemical compositions, but different atomic arrangements with distinct bond angle distributions.
Subject Areas:
Materials,
Chemistry
Instruments:
B18-Core EXAFS
Documents:
d0nr05186a.pdf