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Title: First-Principles Study of Fluorescence in Silver Nanoclusters

Abstract

Mechanisms of efficient fluorescence from biocompatible, ligand-protected silver nanoclusters (AgNC) are explored with an atomistic model of an icosahedral shaped AgNC passivated with 12 cytosine molecules representing single-stranded DNA. Spin-resolved density-functional theory with varying constraints to the total charge was used as a simulation probe to explore the electronic structure and photoluminescence of AgNCs. Visible photoemission in AgNCs is modeled through a synergy of radiative and nonradiative photoinduced dynamics computed by a combination of density matrix and density functional methods with explicit treatment of spin polarization. The ab initio computed charge-to-total energy correlation, Etot(ΔN), of the modeled AgNC shows an approximate 2.2 eV discontinuity at a charge of ΔN = 5, which correlates with the DFT calculated band gap and with concept of superatom with closed shell valence electron count [PNAS 2008, 105, 9157]. UV photoexcitation of this cationic model followed by cascade thermalizations toward the band edges is modeled using Redfield theory, and the corresponding time-integrated emission is calculated. Peak emission near 610 nm is found, consistent with experimentally reported PL in AgNCs. This work gives further insight into the recombination kinetics of AgNC and can be used to aid in tailoring their optical properties to maximize fluorescence efficiencymore » and tunability.« less

Authors:
 [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]
  1. Materials and Nanotechnology Program, North Dakota State University, Fargo, North Dakota 58108, United States
  2. Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, United States
  3. Materials and Nanotechnology Program, North Dakota State University, Fargo, North Dakota 58108, United States; Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1480497
DOE Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 43; Journal ID: ISSN 1932-7447
Country of Publication:
United States
Language:
English

Citation Formats

Brown, Samuel L., Hobbie, Erik K., Tretiak, Sergei, and Kilin, Dmitri S.. First-Principles Study of Fluorescence in Silver Nanoclusters. United States: N. p., 2017. Web. doi:10.1021/acs.jpcc.7b04870.
Brown, Samuel L., Hobbie, Erik K., Tretiak, Sergei, & Kilin, Dmitri S.. First-Principles Study of Fluorescence in Silver Nanoclusters. United States. doi:10.1021/acs.jpcc.7b04870.
Brown, Samuel L., Hobbie, Erik K., Tretiak, Sergei, and Kilin, Dmitri S.. Mon . "First-Principles Study of Fluorescence in Silver Nanoclusters". United States. doi:10.1021/acs.jpcc.7b04870.
@article{osti_1480497,
title = {First-Principles Study of Fluorescence in Silver Nanoclusters},
author = {Brown, Samuel L. and Hobbie, Erik K. and Tretiak, Sergei and Kilin, Dmitri S.},
abstractNote = {Mechanisms of efficient fluorescence from biocompatible, ligand-protected silver nanoclusters (AgNC) are explored with an atomistic model of an icosahedral shaped AgNC passivated with 12 cytosine molecules representing single-stranded DNA. Spin-resolved density-functional theory with varying constraints to the total charge was used as a simulation probe to explore the electronic structure and photoluminescence of AgNCs. Visible photoemission in AgNCs is modeled through a synergy of radiative and nonradiative photoinduced dynamics computed by a combination of density matrix and density functional methods with explicit treatment of spin polarization. The ab initio computed charge-to-total energy correlation, Etot(ΔN), of the modeled AgNC shows an approximate 2.2 eV discontinuity at a charge of ΔN = 5, which correlates with the DFT calculated band gap and with concept of superatom with closed shell valence electron count [PNAS 2008, 105, 9157]. UV photoexcitation of this cationic model followed by cascade thermalizations toward the band edges is modeled using Redfield theory, and the corresponding time-integrated emission is calculated. Peak emission near 610 nm is found, consistent with experimentally reported PL in AgNCs. This work gives further insight into the recombination kinetics of AgNC and can be used to aid in tailoring their optical properties to maximize fluorescence efficiency and tunability.},
doi = {10.1021/acs.jpcc.7b04870},
journal = {Journal of Physical Chemistry. C},
issn = {1932-7447},
number = 43,
volume = 121,
place = {United States},
year = {2017},
month = {10}
}