4 research outputs found
Melting, bubble-like expansion and explosion of superheated plasmonic nanoparticles
We report on time-resolved coherent diffraction imaging of gas-phase silver
nanoparticles, strongly heated via their plasmon resonance. The x-ray
diffraction images reveal a broad range of phenomena for different excitation
strengths, from simple melting over strong cavitation to explosive
disintegration. Molecular dynamics simulations fully reproduce this behavior
and show that the heating induces rather similar trajectories through the phase
diagram in all cases, with the very different outcomes being due only to
whether and where the stability limit of the metastable superheated liquid is
crossed.Comment: 17 pages, 8 figures (including supplemental material
Three-dimensional femtosecond snapshots of isolated faceted nanostructures
The structure and dynamics of isolated nanosamples in free flight can be directly visualized via single-shot coherent diffractive imaging using the intense and short pulses of x-ray free-electron lasers. Wide-angle scattering images encode three-dimensional (3D) morphological information of the samples, but its retrieval remains a challenge. Up to now, effective 3D morphology reconstructions from single shots were only achieved via fitting with highly constrained models, requiring a priori knowledge about possible geometries. Here, we present a much more generic imaging approach. Relying on a model that allows for any sample morphology described by a convex polyhedron, we reconstruct wide-angle diffraction patterns from individual silver nanoparticles. In addition to known structural motives with high symmetries, we retrieve imperfect shapes and agglomerates that were not previously accessible. Our results open unexplored routes toward true 3D structure determination of single nanoparticles and, ultimately, 3D movies of ultrafast nanoscale dynamics.ISSN:2375-254
Three-dimensional femtosecond snapshots of isolated faceted nanostructures
The structure and dynamics of isolated nanosamples in free flight can be directly visualized via single-shot coherent diffractive imaging using the intense and short pulses of x-ray free-electron lasers. Wide-angle scattering images encode three-dimensional (3D) morphological information of the samples, but its retrieval remains a challenge. Up to now, effective 3D morphology reconstructions from single shots were only achieved via fitting with highly constrained models, requiring a priori knowledge about possible geometries. Here, we present a much more generic imaging approach. Relying on a model that allows for any sample morphology described by a convex polyhedron, we reconstruct wide-angle diffraction patterns from individual silver nanoparticles. In addition to known structural motives with high symmetries, we retrieve imperfect shapes and agglomerates that were not previously accessible. Our results open unexplored routes toward true 3D structure determination of single nanoparticles and, ultimately, 3D movies of ultrafast nanoscale dynamics
Generation of Large Vortex-Free Superfluid Helium Nanodroplets
Superfluid helium nanodroplets are an ideal environment for the formation of metastable, self-organized dopant nanostructures. However, the presence of vortices often hinders their formation. Here, we demonstrate the generation of vortex-free helium nanodroplets and explore the size range in which they can be produced. From x-ray diffraction images of xenon-doped droplets, we identify that single compact structures, assigned to vortex-free aggregation, prevail up to
10
8
atoms per droplet. This finding builds the basis for exploring the assembly of far-from-equilibrium nanostructures at low temperatures.ISSN:0031-9007ISSN:1079-711