@article{ZamponiPenfoldNachtegaaletal.2014, author = {Zamponi, Flavio and Penfold, Thomas J. and Nachtegaal, Maarten and L{\"u}bcke, Andrea and Rittmann, Jochen and Milne, Chris J. and Chergui, Majed and van Bokhoven, Jeroen A.}, title = {Probing the dynamics of plasmon-excited hexanethiol-capped gold nanoparticles by picosecond X-ray absorption spectroscopy}, series = {physical chemistry, chemical physics : PCCP}, volume = {2014}, journal = {physical chemistry, chemical physics : PCCP}, number = {16}, issn = {1463-9076}, doi = {10.1039/c4cp03301a}, pages = {23157 -- 23163}, year = {2014}, 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.}, language = {en} } @misc{ZamponiPenfoldNachtegaaletal.2014, author = {Zamponi, Flavio and Penfold, Thomas J. and Nachtegaal, Maarten and L{\"u}bcke, Andrea and Rittmann, Jochen and Milne, Chris J. and Chergui, Majed and van Bokhoven, Jeroen A.}, title = {Probing the dynamics of plasmon-excited hexanethiol-capped gold nanoparticles by picosecond X-ray absorption spectroscopy}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-74492}, pages = {23157 -- 23163}, year = {2014}, 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.}, language = {en} } @article{HerzogLeitenbergerShayduketal.2010, author = {Herzog, Marc and Leitenberger, Wolfram and Shayduk, Roman and van der Veen, Renske Marjan and Milne, Chris J. and Johnson, Steven Lee and Vrejoiu, Ionela and Alexe, Marin and Hesse, Dietrich and Bargheer, Matias}, title = {Ultrafast manipulation of hard x-rays by efficient Bragg switches}, issn = {0003-6951}, doi = {10.1063/1.3402773}, year = {2010}, abstract = {We experimentally demonstrate efficient switching of the hard x-ray Bragg reflectivity of a SrRuO3 /SrTiO3 superlattice by optical excitation of large-amplitude coherent acoustic superlattice phonons. The rocking curve changes drastically on a 1 ps timescale. The (0 0 116) reflection is almost extinguished (Delta R/R-0=-0.91), while the (0 0 118) reflection increases by more than an order of magnitude (Delta R/R-0=24.1). The change of the x-ray structure factor depends nonlinearly on the phonon amplitude, allowing manipulation of the x-ray response on a timescale considerably shorter than the phonon period. Numerical simulations for a superlattice with slightly changed geometry and realistic parameters predict a switching-contrast ratio Delta R/R-0 of 700 with high reflectivity.}, language = {en} } @article{ZamponiPenfoldNachtegaaletal.2014, author = {Zamponi, Flavio and Penfold, Thomas J. and Nachtegaal, Maarten and Luebcke, Andrea and Rittmann, Jochen and Milne, Chris J. and Chergui, Majed and van Bokhoven, Jeroen A.}, title = {Probing the dynamics of plasmon-excited hexanethiol-capped gold nanoparticles by picosecond X-ray absorption spectroscopy}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {42}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c4cp03301a}, pages = {23157 -- 23163}, year = {2014}, 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 similar to 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.}, language = {en} }