Controlled beams of cryo-cooled protein-like nanoparticles.

We report a cryogenic buffer-gas-cell-aerodynamic-lens-stack setup that enables the generation of shock-frozen, dense, and controllable beams of various nanoparticles in the gas phase, including small and low-density species, such as isolated proteins. We demonstrate characterization of the setup using strong-field ionization combined with electron imaging and counting, as well as ion time-of-flight spectrometry, allowing the unambiguous detection of nanoparticles in the protein-size range and full reconstruction of the particle beams, including determination of particle flux and number density. The generation and characterization workflow presented here provides a valuable approach for protein-like sample preparation and delivery in single-particle diffractive imaging, microscopy, and low-temperature nanoscience.