Influence of confined fluids on nanoparticle-to-surroundings energy transfer

Anne Marie Dowgiallo, Kenneth Knappenberger

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Energy transfer from photoexcited nanoparticles to their surroundings was studied for both hollow and solid gold nanospheres (HGNs and SGNs, respectively) using femtosecond time-resolved transient extinction spectroscopy. HGNs having outer diameters ranging from 17 to 78 nm and fluid-filled cavities were synthesized by a sacrificial galvanic replacement method. The HGNs exhibited energy transfer half times that ranged from 105 ± 10 ps to 1010 ± 80 ps as the total particle surface area increased from 1005 to 28 115 nm 2. These data showed behaviors that were categorized into two classes: energy transfer from HGNs to interior fluids that were confined to cavities with radii <15 nm and ≥15 nm. Energy transfer times were also determined for solid gold nanospheres (SGNs) having radii spanning 9-30 nm, with a similar size dependence where the relaxation times increased from 140 ± 10 to 310 ± 15 ps with increasing nanoparticle size. Analysis of the size-dependent energy transfer half times revealed that the distinct relaxation rate constants observed for particle-to-surroundings energy transfer for HGNs with small cavities were the result of reduced thermal conductivity of confined fluids. These data indicate that the thermal conductivity of HGN cavity-confined fluids is approximately one-half as great as it is for bulk liquid water. For all HGNs and SGNs studied, energy dissipation through the solvent and transfer across the particle/surroundings interface both contributed to the energy relaxation process. The current data illustrated the potential of fluid-filled hollow nanostructures to gain insight into the properties of confined fluids.

Original languageEnglish (US)
Pages (from-to)19393-19400
Number of pages8
JournalJournal of the American Chemical Society
Volume134
Issue number47
DOIs
StatePublished - Nov 28 2012

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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