Identification of parameters through which surface chemistry determines the lifetimes of hot electrons in small Au nanoparticles

Kenneth O. Aruda, Mario Tagliazucchi, Christina M. Sweeney, Daniel C. Hannah, George C. Schatz, Emily A. Weiss

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

This paper describes measurements of the dynamics of hot electron cooling in photoexcited gold nanoparticles (Au NPs) with diameters of ∼3.5 nm, and passivated with either a hexadecylamine or hexadecanethiolate adlayer, using ultrafast transient absorption spectroscopy. Fits of these dynamics with temperature-dependent Mie theory reveal that both the electronic heat capacity and the electron-phonon coupling constant are larger for the thiolated NPs than for the aminated NPs, by 40% and 30%, respectively. Density functional theory calculations on ligand-functionalized Au slabs show that the increase in these quantities is due to an increased electronic density of states near the Fermi level upon ligand exchange from amines to thiolates. The lifetime of hot electrons, which have thermalized from the initial plasmon excitation, increases with increasing electronic heat capacity, but decreases with increasing electron- phonon coupling, so the effects of changing surface chemistry on these two quantities partially cancel to yield a hot electron lifetime of thiolated NPs that is only 20% longer than that of aminated NPs. This analysis also reveals that incorporation of a temperature-dependent electron-phonon coupling constant is necessary to adequately fit the dynamics of electron cooling.

Original languageEnglish
Pages (from-to)4212-4217
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume110
Issue number11
DOIs
Publication statusPublished - Mar 12 2013

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Keywords

  • Dissipation
  • Two-temperature model

ASJC Scopus subject areas

  • General

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