TY - JOUR
T1 - Structural Evolution of Core-Shell Gold Nanoclusters
T2 - Aun- (n = 42-50)
AU - Pande, Seema
AU - Huang, Wei
AU - Shao, Nan
AU - Wang, Lei Ming
AU - Khetrapal, Navneet
AU - Mei, Wai Ning
AU - Jian, Tian
AU - Wang, Lai Sheng
AU - Zeng, Xiao Cheng
N1 - Funding Information:
The experiment done at Brown University was supported by the National Science Foundation (CHE-1632813 to L.S.W.). X.C.Z. was supported by a grant from Nebraska Center for Energy Sciences Research. The calculations were done in the Holland Computing Center at University of Nebraska-Lincoln.
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/11/22
Y1 - 2016/11/22
N2 - Gold nanoclusters have attracted great attention in the past decade due to their remarkable size-dependent electronic, optical, and catalytic properties. However, the structures of large gold clusters are still not well-known because of the challenges in global structural searches. Here we report a joint photoelectron spectroscopy (PES) and theoretical study of the structural evolution of negatively charged core-shell gold nanoclusters (Aun-) for n = 42-50. Photoelectron spectra of size-selected Aun- clusters are well resolved with distinct spectral features, suggesting a dominating structural type. The combined PES data and density functional calculations allow us to systematically identify the global minimum or candidates of the global minima of these relatively large gold nanoclusters, which are found to possess low-symmetry structures with gradually increasing core sizes. Remarkably, the four-atom tetrahedral core, observed first in Au33-, continues to be highly robust and is even present in clusters as large as Au42-. Starting from Au43-, a five-atom trigonal bipyramidal core appears and persists until Au47-. Au48- possesses a six-atom core, while Au49- and Au50- feature seven- and eight-atom cores, respectively. Notably, both Au46- and Au47- contain a pyramidal Au20 motif, which is stacked with another truncated pyramid by sharing a common 10-atom triangular face. The present study sheds light on our understanding of the structural evolution of the medium-sized gold nanoclusters, the shells and core as well as how the core-shell structures may start to embrace the golden pyramid (bulk-like) fragment.
AB - Gold nanoclusters have attracted great attention in the past decade due to their remarkable size-dependent electronic, optical, and catalytic properties. However, the structures of large gold clusters are still not well-known because of the challenges in global structural searches. Here we report a joint photoelectron spectroscopy (PES) and theoretical study of the structural evolution of negatively charged core-shell gold nanoclusters (Aun-) for n = 42-50. Photoelectron spectra of size-selected Aun- clusters are well resolved with distinct spectral features, suggesting a dominating structural type. The combined PES data and density functional calculations allow us to systematically identify the global minimum or candidates of the global minima of these relatively large gold nanoclusters, which are found to possess low-symmetry structures with gradually increasing core sizes. Remarkably, the four-atom tetrahedral core, observed first in Au33-, continues to be highly robust and is even present in clusters as large as Au42-. Starting from Au43-, a five-atom trigonal bipyramidal core appears and persists until Au47-. Au48- possesses a six-atom core, while Au49- and Au50- feature seven- and eight-atom cores, respectively. Notably, both Au46- and Au47- contain a pyramidal Au20 motif, which is stacked with another truncated pyramid by sharing a common 10-atom triangular face. The present study sheds light on our understanding of the structural evolution of the medium-sized gold nanoclusters, the shells and core as well as how the core-shell structures may start to embrace the golden pyramid (bulk-like) fragment.
KW - core-shell structures
KW - gold anion clusters
KW - gold nanoclusters
KW - photoelectron spectroscopy
KW - structural evolution
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U2 - 10.1021/acsnano.6b04330
DO - 10.1021/acsnano.6b04330
M3 - Article
C2 - 27794617
AN - SCOPUS:84997142661
VL - 10
SP - 10013
EP - 10022
JO - ACS Nano
JF - ACS Nano
SN - 1936-0851
IS - 11
ER -