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Scientific data 3, 160064 -(2016). doi:10.1038/sdata.2016.64, Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a well-characterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 μm diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 Ångström were recorded. The diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here., Published by Nature Publ. Group, London

To advance microfluidic integration, we present the use of two-photon additive manufacturing to fold 2D channel layouts into compact free-form 3D fluidic circuits with nanometer precision. We demonstrate this technique by tailoring microfluidic nozzles and mixers for time-resolved structural biology at X-ray free-electron lasers (XFELs). We achieve submicron jets with speeds exceeding 160 m s−1, which allows for the use of megahertz XFEL repetition rates. By integrating an additional orifice, we implement a low consumption flow-focusing nozzle, which is validated by solving a hemoglobin structure. Also, aberration-free in operando X-ray microtomography is introduced to study efficient equivolumetric millisecond mixing in channels with 3D features integrated into the nozzle. Such devices can be printed in minutes by locally adjusting print resolution during fabrication. This technology has the potential to permit ultracompact devices and performance improvements through 3D flow optimization in all fields of microfluidic engineering., There is a need for more robust sample delivery methods for serial crystallography. Here the authors present the design and characterization of ultracompact 3D microfluidic devices that can be printed, which require less sample, have a lower background signal and allow 3D mixing for time resolved experiments.

We report on the use of multilayer Laue lenses to focus the intense X-ray Free Electron Laser (XFEL) beam at the European XFEL to a spot size of a few tens of nanometers. We present the procedure to align and characterize these lenses and discuss challenges working with the pulse trains from this unique x-ray source.

We present a comparison between a numerical model and the experimental results on the generation of a first-order Bessel-Gaussian optical funnel for guiding of airborne microparticles.

Facilitating the very short and intense pulses from an X-ray laser for the purpose of imaging small bioparticles carries the potential for structure determination at atomic resolution without the need for crystallization. In this study, experimental strategies for this idea are explored based on data collected at the Linac Coherent Light Source from 40 nm virus particles injected into a hard X-ray beam., This study explores the capabilities of the Coherent X-ray Imaging Instrument at the Linac Coherent Light Source to image small biological samples. The weak signal from small samples puts a significant demand on the experiment. Aerosolized Omono River virus particles of ∼40 nm in diameter were injected into the submicrometre X-ray focus at a reduced pressure. Diffraction patterns were recorded on two area detectors. The statistical nature of the measurements from many individual particles provided information about the intensity profile of the X-ray beam, phase variations in the wavefront and the size distribution of the injected particles. The results point to a wider than expected size distribution (from ∼35 to ∼300 nm in diameter). This is likely to be owing to nonvolatile contaminants from larger droplets during aerosolization and droplet evaporation. The results suggest that the concentration of nonvolatile contaminants and the ratio between the volumes of the initial droplet and the sample particles is critical in such studies. The maximum beam intensity in the focus was found to be 1.9 × 1012 photons per µm2 per pulse. The full-width of the focus at half-maximum was estimated to be 500 nm (assuming 20% beamline transmission), and this width is larger than expected. Under these conditions, the diffraction signal from a sample-sized particle remained above the average background to a resolution of 4.25 nm. The results suggest that reducing the size of the initial droplets during aerosolization is necessary to bring small particles into the scope of detailed structural studies with X-ray lasers.

Scientific Reports 7: Article number: 44628; published online: 16 March 2017; updated: 21 June 2017. In this Article, Henry N. Chapman is incorrectly listed as being affiliated with ‘Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA’ and an additional affiliation was omitted.

A numerical simulation infrastructure capable of calculating the flow of gas and the trajectories of particles through an aerodynamic lens injector is presented. The simulations increase the fundamental understanding and predict optimized injection geometries and parameters. Our simulation results were compared to previous reports and also validated against experimental data for 500 nm polystyrene spheres from an aerosol-beam-characterization setup. The simulations yielded a detailed understanding of the radial phase-space distribution and highlighted weaknesses of current aerosol injectors for single-particle diffractive imaging. With the aid of these simulations we developed new experimental implementations to overcome current limitations.

Scientific data 4, 170079 (2017). doi:10.1038/sdata.2017.79, Single-particle diffraction from X-ray Free Electron Lasers offers the potential for molecular structure determination without the need for crystallization. In an effort to further develop the technique, we present a dataset of coherent soft X-ray diffraction images of Coliphage PR772 virus, collected at the Atomic Molecular Optics (AMO) beamline with pnCCD detectors in the LAMP instrument at the Linac Coherent Light Source. The diameter of PR772 ranges from 65–70 nm, which is considerably smaller than the previously reported ~600 nm diameter Mimivirus. This reflects continued progress in XFEL-based single- particle imaging towards the single molecular imaging regime. The data set contains significantly more single particle hits than collected in previous experiments, enabling the development of improved statistical analysis, reconstruction algorithms, and quantitative metrics to determine resolution and self-consistency., Published by Macmillan, London

SPIE Nanoscience + Engineering, San Diego, California, 17 Aug 2016 - 21 Aug 2016 ; Proceedings of SPIE 9022, 99220K(2016). doi:10.1117/12.2239171, Optical trapping of light-absorbing particles in a gas environment is usually dominated by laser-induced thermal or photophoretic forces, which can be orders of magnitude higher than the force due to radiation pressure. Particle guiding with photophoretic forces over large distances in open air was recently realised by an optical pipeline, formed by a vortex laser beam of doughnut-like intensity profile, with a high-intensity ring of light that surrounds a dark core. We are adapting the optical pipeline concept for the purpose of guiding aerosolized particles into the intense focus of a x-ray free-electron laser (XFEL), in order to enable high-efficiency femtosecond x-ray coherent diffractive imaging (CDI). XFEL-based CDI allows single-shot nanometer-resolution imaging, and multi-shot Angstrom-resolution tomography in the case of reproducible nanoparticles, at a time resolution better than 10 femtoseconds. Remarkably, by imaging at timescales shorter than atomic motion, the crucial resolution-limiting effects of radiation damage may be overcome for radiation-sensitive targets such as viruses and biomolecules. Following on our previous work, we are developing an optical first-order Bessel-like beam with a variable-diameter hollow core and an axial-to-lateral aspect ratio up to ~2000, that can be used to guide particles with a spatial precision of less than a few µm over centimetre-long distances. We present the ways to control the beam divergence aiming to focus the stream of particles by thermal forces and forces of radiation pressure, analyse the forces acting on the particle in the beam, and uncover the beam structure and intensity to apply for a real-time experiment with XFEL. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only., Published by SPIE, Bellingham, Wash.

Optical trapping of light-absorbing particles in a gaseous environment is governed by a laser-induced photophoretic force, which can be orders of magnitude stronger than the force of radiation-pressure induced by the same light intensity. In spite of many experimental studies, the exact theoretical background underlying the photophoretic force and the prediction of its influence on the particle motion is still in its infancy. Here, we report the results of a quantitative analysis of the photophoretic force and the stiffness of trapping achieved by levitating graphite and carbon-coated glass shells of calibrated sizes in an upright diverging hollow-core vortex beam, which we refer to as an ‘optical funnel’. The measurements of forces were conducted in air at various gas pressures in the range from 5 mbar to 2 bar. The results of these measurements lay the foundation for mapping the optically induced force to the intensity distribution in the trap. The mapping, in turn, provides the necessary information to model flight trajectories of particles of various sizes entering the beam at given initial speed and position relative to the beam axis. Finally, we determined the limits of the parameter space for the particle speed, size, and radial offset to the beam axis, all linked to the laser power and the particular laser beam structure. These results establish the grounds for developing a touch-free optical system for precisely positioning sub-micrometer bioparticles at the focal spot of an x-ray free electron laser, which would significantly enhance the efficiency of studying nanoscale morphology of proteins and biomolecules in femtosecond coherent diffractive imaging experiments.

A major challenge in high-resolution x-ray free-electron laser-based coherent diffractive imaging is the development of aerosol injectors that can efficiently deliver particles to the peak intensity of the focused X-ray beam. Here, we consider the use of a simple convergent-orifice nozzle for producing tightly focused beams of particles. Through optical imaging we show that 0.5 μm particles can be focused to a full-width at half maximum diameter of 4.2 μm, and we demonstrate the use of such a nozzle for injecting viruses into a micro-focused soft-X-ray FEL beam.

Optical Trapping and Optical Micromanipulation XII, San Diego, California, 9 Aug 2015 - 12 Aug 2015 ; Proceedings of SPIE 9548, 95480H(2015). doi:10.1117/12.2191442, Optical trapping of light-absorbing particles in a gaseous environment is governed by a laser-induced photophoreticforce, which can be orders of magnitude stronger than the force of radiation pressure induced by the same lightintensity. In spite of many experimental studies, the exact theoretical background underlying the photophoreticforce and the prediction of its influence on the particle motion is still in its infancy. Here, we report the results of aquantitative analysis of the photophoretic force and the stiffness of trapping achieved by levitating graphite andcarbon-coated glass shells of calibrated sizes in an upright diverging hollow-core vortex beam, which we refer to asan ‘optical funnel’. The measurements of forces were conducted in air at various gas pressures in the range from 5mbar to 2 bar. The results of these measurements lay the foundation for developing a touch-free optical system forprecisely positioning sub-micrometer bioparticles at the focal spot of an x-ray free electron laser, which wouldsignificantly enhance the efficiency of studying nanoscale morphology of proteins and biomolecules in femtosecondcoherent diffractive imaging experiments., Published by SPIE, Bellingham, Wash.