Relaxation Dynamics of Electronically Coupled Au20(SC8H9)15-n-glyme-Au20(SC8H9)15 Monolayer-Protected Cluster Dimers

Patrick J. Herbert, Chongyue Yi, W. Scott Compel, Christopher J. Ackerson, Kenneth L. Knappenberger

Research output: Contribution to journalArticle

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Abstract

The electronic relaxation dynamics of photoexcited Au20(SC8H9)15-n-glyme and Au20(SC8H9)15-n-glyme-Au20(SC8H9)15 (n-= di-, tri-, and tetra-) dimers, where glyme refers to n-ethylene glycol dimethyl ether bridging molecules, were studied using pump-probe femtosecond time-resolved transient absorption spectroscopy (fsTAS). The utilization of n-glyme molecular bridging linkers provided a method to prepare Au20(SC8H9)15-n-glyme-Au20(SC8H9)15 dimers with control over intercluster spatial separation. A dimer-specific electronic absorption resonance was observed at 2.6 eV. Analysis of fsTAS differential spectra for dimer species revealed a pump-probe waiting time-dependent blue shift of the low energy excited-state absorption (ESA) feature, suggesting electronic relaxation into a dimer-specific excited-state. Single probe-energy differential signal amplitude analysis of the ESA feature yielded a distance-dependent growth component for the electronic relaxation dynamics with time constants of 130 ± 20, 60 ± 8, and 36 ± 6 ps for the diglyme, triglyme, and tetraglyme-bridged dimers, respectively. The increase in relaxation time was attributed to intercluster distance-dependent stabilization of dimer-specific electronic excited states. These results suggest a state-specific mechanism for intercluster electronic relaxation.

Original languageEnglish (US)
Pages (from-to)19251-19258
Number of pages8
JournalJournal of Physical Chemistry C
Volume122
Issue number33
DOIs
StatePublished - Aug 23 2018

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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