25 research outputs found
New aerodynamic lens injector for single particle diffractive imaging
An aerodynamic lens injector was developed specifically for the needs of single-particle diffractive imaging experiments at free-electron lasers. Its design allows for quick changes of injector geometries and focusing properties in order to optimize injection for specific individual samples. Here, we present results of its first use at the FLASH free-electron-laser facility. Recorded diffraction patterns of polystyrene spheres are modeled using Mie scattering, which allowed for the characterization of the particle beam under diffractive-imaging conditions and yield good agreement with particle-trajectory simulations
Time-resolved single-particle x-ray scattering reveals electron-density as coherent plasmonic-nanoparticle-oscillation source
Dynamics of optically-excited plasmonic nanoparticles are presently
understood as a series of sequential scattering events, involving
thermalization processes after pulsed optical excitation. One important step is
the initiation of nanoparticle breathing oscillations. According to established
experiments and models, these are caused by the statistical heat transfer from
thermalized electrons to the lattice. An additional contribution by hot
electron pressure has to be included to account for phase mismatches that arise
from the lack of experimental data on the breathing onset. We used optical
transient-absorption spectroscopy and time-resolved single-particle
x-ray-diffractive imaging to access the excited electron system and lattice.
The time-resolved single-particle imaging data provided structural information
directly on the onset of the breathing oscillation and confirmed the need for
an additional excitation mechanism to thermal expansion, while the observed
phase-dependence of the combined structural and optical data contrasted
previous studies. Therefore, we developed a new model that reproduces all our
experimental observations without using fit parameters. We identified
optically-induced electron density gradients as the main driving source.Comment: 32 pages, 5 figures, 1 supporting information document include
On the use of multilayer Laue lenses with X-ray Free Electron Lasers
Multilayer Laue lenses were used for the first time to focus x-rays from an X-ray Free Electron Laser (XFEL). In an experiment, which was performed at the European XFEL, we demonstrated focusing to a spot size of a few tens of nanometers. A series of runs in which the number of pulses per train was increased from 1 to 2, 3, 4, 5, 6, 7, 10, 20 and 30 pulses per train, all with a pulse separation of 3.55 us, was done using the same set of lenses. The increase in the number of pulses per train was accompanied with an increase of x-ray intensity (transmission) from 9% to 92% at 5 pulses per train, and then the transmission was reduced to 23.5 % when the pulses were increased further. The final working condition was 30 pulses per train and 23.5% transmission. Only at this condition we saw that the diffraction efficiency of the MLLs changed over the course of a pulse train, and this variation was reproducible from train to train. We present the procedure to align and characterize these lenses and discuss challenges working with the pulse trains from this unique x-ray source
3D diffractive imaging of nanoparticle ensembles using an X-ray laser
We report the 3D structure determination of gold nanoparticles (AuNPs) by X-ray single particle imaging (SPI). Around 10 million diffraction patterns from gold nanoparticles were measured in less than 100 hours of beam time, more than 100 times the amount of data in any single prior SPI experiment, using the new capabilities of the European X-ray free electron laser which allow measurements of 1500 frames per second. A classification and structural sorting method was developed to disentangle the heterogeneity of the particles and to obtain a resolution of better than 3 nm. With these new experimental and analytical developments, we have entered a new era for the SPI method and the path towards close-to-atomic resolution imaging of biomolecules is apparent
New aerodynamic lens injector for single particle diffractive imaging
An aerodynamic lens injector was developed specifically for the needs of single-particle diffractive imaging experiments at free-electron lasers. Its design allows for quick changes of injector geometries and focusing properties in order to optimize injection for specific individual samples. Here, we present results of its first use at the FLASH free-electron-laser facility. Recorded diffraction patterns of polystyrene spheres are modeled using Mie scattering, which allowed for the characterization of the particle beam under diffractive-imaging conditions and yielded good agreement with particle-trajectory simulations. The complex refractive index of polystyrene at λ=4.5nm was determined as m=0.976−0.001i
New aerodynamic lens injector for single particle diffractive imaging
An aerodynamic lens injector was developed specifically for the needs of single-particle diffractive imaging experiments at free-electron lasers. Its design allows for quick changes of injector geometries and focusing properties in order to optimize injection for specific individual samples. Here, we present results of its first use at the FLASH free-electron-laser facility. Recorded diffraction patterns of polystyrene spheres are modeled using Mie scattering, which allowed for the characterization of the particle beam under diffractive-imaging conditions and yield good agreement with particle-trajectory simulations