Single Particles, clusters, and Biomolecules (SPB): Structure determination of single particles - atomic clusters, biomolecules, virus particles, cells
The SPB instrument aims at the investigation of 2D and 3D structures of single particles in the gas phase. Scientific areas of application are materials sciences, nanomaterials and structural and cell biology.
Experiments utilize scattering of coherent X-rays and detecting the coherent diffraction pattern. Examples of particles are single biomolecules, functional units of cells forming ensembles of biomolecules, entire cells or microorganisms, but also materials science relevant particles like nanocrystals or atomic clusters. In principle an atomic resolution of better than a nanometre is aimed for in the experiments in order to retrieve the structural information necessary to investigate function.
SPB Workshop 2008
The first SPB workshop took place in Uppsala in November 2008. Visit the workshop page to get more information including the slides of the given presentations.
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Initial design, TDR-2006 & startup configuration:
- Utilization of scattering from single particles and detection of forward scattered diffraction pattern using 2D detection systems
- Experiments in general require maximum obtainable number of photons/pulse in order to achieve significant scattering patterns.
- X-ray beam will be focused to focal spots of ∼100 nm, 1 μm and 10 μm.
- The wavefront of the focused X-ray pulse shall be flat or at least known.
- As short as possible pulse durations are required.
- Bandwidth remains to be determined.
- The X-ray beam requires pulse-by-pulse diagnostics of intensity, position, (spot size), spectrum. Regular measurement of X-ray wavefront and pulse arrival is wishful. This task might be achieved using the beam fraction transmitted through the sample chamber.
- Samples will be jets, gas streams or injected particles. Experiments are done under UHV vacuum conditions (at least background pressure).
- An extension of the instrument could be the development of techniques to pre-align the particles in the beam. Likewise the scattering patterns would become easier to analyse.
- Extensive diagnostics of the interaction of the X-ray pulse with the particle is required: particle detection, light emission spectrometry, microscopy.
- Detection will be achieved by use of the newly developed 2D pixel detectors. In the moment the HPAD detector with a pixel size of (200 μm)2 is foreseen for this instrument. Detector distance can vary from 0.5 to 2.0m. The detector has a central hole for the direct beam. Number of pixels is 1 million.
- Construction of one X-ray hutch is foreseen for this instrument. In addition a control hutch will be built for operation of the instrument.
- Initially the instrument will not utilize femtosecond or high-energy optical lasers for pump-probe experiments.
Beamline design considerations
- Instrument is located at SASE 1 beamline (designed for fixed energy operation at 12.4 keV, providing horizontal liear polarization).
- Instrument is about 1000 m from source point.
- Beamline will be designed for optimized transport of coherent X-ray beam.
- Beamline will feature a monochromator allowing a resolution of 10-5-10-4 thereby raising the longitudinal coherence length.