Composition-dependent electronic energy relaxation dynamics of metal domains as revealed by bimetallic Au144−xAgx(SC8H9)60 monolayer-protected clusters. Issue 22 (23rd May 2017)

• Record Type: Journal Article
• Authors: Zheng, Hongjun; Tofanelli, Marcus A.; Ackerson, Christopher J.; Knappenberger, Kenneth L.
• Is Part Of: Physical chemistry chemical physics. Volume 19:Issue 22(2017)
• Page Start: 14471
• Page End: 14477
• Publication Date: 2017-05-23
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c7cp00884h
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : The influence of nanoscale composition on electronic relaxation is determined using monolayer-protected clusters as structurally precise model systems. Abstract : We examined the electronic relaxation dynamics for mono and bimetallic Au144− x Ag x (SC8 H9 )60 monolayer-protected clusters (MPCs) using femtosecond time-resolved transient extinction spectroscopy. MPCs provide compositionally well-defined model systems for structure-specific determination of nanoscale electronic properties. Based on pulse-energy-dependent transient extinction data, we quantified electron–phonon coupling constants for three distinct Au144− x Ag x (SC8 H9 )60 MPC samples, where x = 0, 0 < x < 30, and x ∼ 30, as G x =0 = (1.61 ± 0.1) × 10 16 W m −3 K −1, G x <30 = (1.74 ± 0.1) × 10 16 W m −3 K −1 and G x ∼30 = (2.07 ± 0.15) × 10 16 W m −3 K −1, respectively. These results reflect a trend of greater electron–phonon coupling efficiency with increasing silver content. Based on these data, we conclude that gold-atom replacement by silver occurs at surface sites of the 114-atom metal core of the MPC. Definitive determinations of functional response to nanoscale "alloy" formation and dopant inclusion are critical to establishing predictive models for the development of materials that feature nanoparticles as active components.