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J Am Chem Soc. 2019 Apr 3;141(13):5314-5325. doi: 10.1021/jacs.8b13558. Epub 2019 Mar 25.

A Mono-cuboctahedral Series of Gold Nanoclusters: Photoluminescence Origin, Large Enhancement, Wide Tunability, and Structure-Property Correlation.

Author information

1
Department of Chemistry , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States.
2
State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science , Fudan University , Shanghai 200438 , China.
3
Center for Functional Nanomaterials , Brookhaven National Laboratory , Upton , New York 11973 , United States.
4
National Energy Technology Laboratory (NETL), Department of Energy , Pittsburgh , Pennsylvania 15236 , United States.

Abstract

The origin of the near-infrared photoluminescence (PL) from thiolate-protected gold nanoclusters (Au NCs, <2 nm) has long been controversial, and the exact mechanism for the enhancement of quantum yield (QY) in many works remains elusive. Meanwhile, based upon the sole steady-state PL analysis, it is still a major challenge for researchers to map out a definitive relationship between the atomic structure and the PL property and understand how the Au(0) kernel and Au(I)-S surface contribute to the PL of Au NCs. Herein, we provide a paradigm study to address the above critical issues. By using a correlated series of "mono-cuboctahedral kernel" Au NCs and combined analyses of steady-state, temperature-dependence, femtosecond transient absorption, and Stark spectroscopy measurements, we have explicitly mapped out a kernel-origin mechanism and clearly elucidate the surface-structure effect, which establishes a definitive atomic-level structure-emission relationship. A ∼100-fold enhancement of QY is realized via suppression of two effects: (i) the ultrafast kernel relaxation and (ii) the surface vibrations. The new insights into the PL origin, QY enhancement, wavelength tunability, and structure-property relationship constitute a major step toward the fundamental understanding and structural-tailoring-based modulation and enhancement of PL from Au NCs.

PMID:
30860834
DOI:
10.1021/jacs.8b13558

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