A Time-Dependent Density Functional Theory Study of the Impact of Ligand Passivation on the Plasmonic Behavior of Ag Nanoclusters

Adam P. Ashwell, Mark A Ratner, George C Schatz

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

We present a detailed study of the impact of ligand passivation on the electronic structures and optical properties of plasmonic Ag nanoclusters using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The clusters studied are Ag135+, Ag25SH18-, Ag25NH218-, Ag3214+, and Ag44SH304-We find that the highest occupied ligand orbitals from S (3p) and N (2p) appear just above the conduction band, and this leads to significant ligand-to-metal charge transfer transitions at high energies. Dielectric screening associated with ligand passivation results in reduced HOMO-LUMO gaps and in an increased gap between the HOMO and the valence band associated with the Ag 4d orbitals. Ligand field effects result in splitting of plasmonic peaks, leading to reduced mixing between nearby single-particle excitations. The magnitude of these effects is found to decrease when thiolate ligands are replaced with amine ligands. We also find that, in the case of the Ag44SH304- cluster, the ligands localize plasmonic excitations into the core of the cluster.

Original languageEnglish
JournalAdvances in Quantum Chemistry
DOIs
Publication statusAccepted/In press - 2017

Fingerprint

Nanoclusters
nanoclusters
Passivation
passivity
Density functional theory
density functional theory
Ligands
ligands
orbitals
Valence bands
Conduction bands
excitation
Electronic structure
Amines
Charge transfer
amines
Screening
conduction bands
screening
Optical properties

Keywords

  • Ligand-protected
  • Nanocluster
  • Optical response
  • Plasmon
  • Time-dependent density functional theory

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

@article{f7a5e1b232424ed1841f946750fb128b,
title = "A Time-Dependent Density Functional Theory Study of the Impact of Ligand Passivation on the Plasmonic Behavior of Ag Nanoclusters",
abstract = "We present a detailed study of the impact of ligand passivation on the electronic structures and optical properties of plasmonic Ag nanoclusters using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The clusters studied are Ag135+, Ag25SH18-, Ag25NH218-, Ag3214+, and Ag44SH304-We find that the highest occupied ligand orbitals from S (3p) and N (2p) appear just above the conduction band, and this leads to significant ligand-to-metal charge transfer transitions at high energies. Dielectric screening associated with ligand passivation results in reduced HOMO-LUMO gaps and in an increased gap between the HOMO and the valence band associated with the Ag 4d orbitals. Ligand field effects result in splitting of plasmonic peaks, leading to reduced mixing between nearby single-particle excitations. The magnitude of these effects is found to decrease when thiolate ligands are replaced with amine ligands. We also find that, in the case of the Ag44SH304- cluster, the ligands localize plasmonic excitations into the core of the cluster.",
keywords = "Ligand-protected, Nanocluster, Optical response, Plasmon, Time-dependent density functional theory",
author = "Ashwell, {Adam P.} and Ratner, {Mark A} and Schatz, {George C}",
year = "2017",
doi = "10.1016/bs.aiq.2017.01.001",
language = "English",
journal = "Advances in Quantum Chemistry",
issn = "0065-3276",
publisher = "Academic Press Inc.",

}

TY - JOUR

T1 - A Time-Dependent Density Functional Theory Study of the Impact of Ligand Passivation on the Plasmonic Behavior of Ag Nanoclusters

AU - Ashwell, Adam P.

AU - Ratner, Mark A

AU - Schatz, George C

PY - 2017

Y1 - 2017

N2 - We present a detailed study of the impact of ligand passivation on the electronic structures and optical properties of plasmonic Ag nanoclusters using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The clusters studied are Ag135+, Ag25SH18-, Ag25NH218-, Ag3214+, and Ag44SH304-We find that the highest occupied ligand orbitals from S (3p) and N (2p) appear just above the conduction band, and this leads to significant ligand-to-metal charge transfer transitions at high energies. Dielectric screening associated with ligand passivation results in reduced HOMO-LUMO gaps and in an increased gap between the HOMO and the valence band associated with the Ag 4d orbitals. Ligand field effects result in splitting of plasmonic peaks, leading to reduced mixing between nearby single-particle excitations. The magnitude of these effects is found to decrease when thiolate ligands are replaced with amine ligands. We also find that, in the case of the Ag44SH304- cluster, the ligands localize plasmonic excitations into the core of the cluster.

AB - We present a detailed study of the impact of ligand passivation on the electronic structures and optical properties of plasmonic Ag nanoclusters using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The clusters studied are Ag135+, Ag25SH18-, Ag25NH218-, Ag3214+, and Ag44SH304-We find that the highest occupied ligand orbitals from S (3p) and N (2p) appear just above the conduction band, and this leads to significant ligand-to-metal charge transfer transitions at high energies. Dielectric screening associated with ligand passivation results in reduced HOMO-LUMO gaps and in an increased gap between the HOMO and the valence band associated with the Ag 4d orbitals. Ligand field effects result in splitting of plasmonic peaks, leading to reduced mixing between nearby single-particle excitations. The magnitude of these effects is found to decrease when thiolate ligands are replaced with amine ligands. We also find that, in the case of the Ag44SH304- cluster, the ligands localize plasmonic excitations into the core of the cluster.

KW - Ligand-protected

KW - Nanocluster

KW - Optical response

KW - Plasmon

KW - Time-dependent density functional theory

UR - http://www.scopus.com/inward/record.url?scp=85012886290&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85012886290&partnerID=8YFLogxK

U2 - 10.1016/bs.aiq.2017.01.001

DO - 10.1016/bs.aiq.2017.01.001

M3 - Article

AN - SCOPUS:85012886290

JO - Advances in Quantum Chemistry

JF - Advances in Quantum Chemistry

SN - 0065-3276

ER -