Rayleigh-scattering microscopy for tracking and sizing nanoparticles in focused aerosol beams

Abstract

Rayleigh-scattering microscopy permits tracking and sizing of aerosolized particles down to 40 nm in diameter. It lays the foundation for lab-based injector development and online injection diagnostics for X-ray free-electron laser (XFEL) research.

Light-sheet imaging for the recording of transverse absolute density distributions of gas-phase particle-beams from nanoparticle injectors

“…The velocity distribution of all particles measured at a certain distance from the ALS exit is the sum of the individual velocity probability distributions, see as a function of distance to the ALS exit. Both, mean velocity and the width of the velocity distribution increased with distance from the ALS exit, consistent with recent observations [10]. We ascribe the increasing velocity to acceleration by the helium gas co-emerging from the ALS, hinting at the need to correlate this acceleration with measurements of the gas density [8] in future work.…”

Electrospray sample injection for single-particle imaging with X-ray lasers

“…1b) by measuring the size of particles that are formed when injecting sucrose solution 19 . Sizes were measured by Rayleigh scattering microscopy (RSM) 8 and, in addition, by XFEL diffraction 5,12 . The droplets generated with the GDVN span a wide range of diameters (500 to 2000 nm) whereas droplets generated with the ES aerosoliser are smaller, and more monodisperse (100 to 200 nm).…”

“…Critical for the success of these pioneering studies were high-fluence XFEL beams, specialised detectors, low background noise, and efficient sample delivery into the XFEL focus 4,5,7 . The most widely used injector for this approach, the Uppsala injector 8 , generates a droplet aerosol by atomising the sample solution with a gas-dynamic virtual nozzle (GDVN) 9 . The volatile droplet components evaporate, leaving behind one aerosol particle for every occupied droplet.…”

Biological single-particle imaging using XFELs – towards the next resolution revolution

“…Their set-up is also capable -if properly calibrated -of estimating the size of the detected particles in the aerosol. This is very important for improving the sample and for optimizing sample delivery for XFEL experiments (Hantke et al, 2018). Particle-beam focusing as function of entrance pressure and particle diameter [reproduced from Hantke et al (2018)].…”

“…This is very important for improving the sample and for optimizing sample delivery for XFEL experiments (Hantke et al, 2018). Particle-beam focusing as function of entrance pressure and particle diameter [reproduced from Hantke et al (2018)]. (a) Blue dots represent measured particle positions of injected polystyrene spheres (70 nm and 220 nm in diameter) at entrance pressures of 0.6 mbar and 1.8 mbar, respectively.…”