title: Probing the dynamics of plasmon-excited hexanethiol-capped gold nanoparticles by picosecond X-ray absorption spectroscopy.
abstract: Picosecond X-ray absorption spectroscopy (XAS) is used to investigate the electronic and structural dynamics initiated by plasmon excitation of 1.8 nm diameter Au nanoparticles (NPs) functionalised with 1-hexanethiol. We show that 100 ps after photoexcitation the transient XAS spectrum is consistent with an 8% expansion of the Au-Au bond length and a large increase in disorder associated with melting of the NPs. Recovery of the ground state occurs with a time constant of ∼1.8 ns, arising from thermalisation with the environment. Simulations reveal that the transient spectrum exhibits no signature of charge separation at 100 ps and allows us to estimate an upper limit for the quantum yield (QY) of this process to be <0.1.
authors.affiliation: Department of Chemistry and Applied Biosciences, ETH Zurich, Switzerland. jeroen.vanbokhoven@chem.ethz.ch.
authors.forename: Flavio
authors.initials: F
authors.lastname: Zamponi
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Penfold
authors.forename: Maarten
authors.initials: M
authors.lastname: Nachtegaal
authors.forename: Andrea
authors.initials: A
authors.lastname: Lübcke
authors.forename: Jochen
authors.initials: J
authors.lastname: Rittmann
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Milne
authors.forename: Majed
authors.initials: M
authors.lastname: Chergui
authors.forename: Jeroen A
authors.initials: JA
authors.lastname: van Bokhoven