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This content will become publicly available on April 16, 2019

Title: Sharp Transition from Nonmetallic Au 246 to Metallic Au 279 with Nascent Surface Plasmon Resonance

Here, the optical properties of metal nanoparticles have attracted wide interest. Recent progress in controlling nanoparticles with atomic precision (often called nanoclusters) provide new opportunities for investigating many fundamental questions, such as the transition from excitonic to plasmonic state, which is a central question in metal nanoparticle research because it provides insights into the origin of surface plasmon resonance (SPR) as well as the formation of metallic bond. However, this question still remains elusive because of the extreme difficulty in preparing atomically precise nanoparticles larger than 2 nm. Here we report the synthesis and optical properties of an atomically precise Au 279(SR) 84 nanocluster. Femtosecond transient absorption spectroscopic analysis reveals that the Au 279 nanocluster shows a laser power dependence in its excited state lifetime, indicating metallic state of the particle, in contrast with the nonmetallic electronic structure of the Au 246(SR) 80 nanocluster. Steady-state absorption spectra reveal that the nascent plasmon band of Au 279 at 506 nm shows no peak shift even down to 60 K, consistent with plasmon behavior. The sharp transition from nonmetallic Au 246 to metallic Au 279 is surprising and will stimulate future theoretical work on the transition and many other relevant issues.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [2] ;  [2] ; ORCiD logo [3] ; ORCiD logo [1]
  1. Carnegie Mellon Univ., Pittsburgh, PA (United States)
  2. Univ. of Toledo, Toledo, OH (United States)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-207860-2018-JAAM
Journal ID: ISSN 0002-7863
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 140; Journal Issue: 17; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1460828