title: Thorough small-angle X-ray scattering analysis of the instability of liquid micro-jets in air.
abstract: Liquid jets are of interest, both for their industrial relevance and for scientific applications (more important, in particular for X-rays, after the advent of free-electron lasers that require liquid jets as sample carrier). Instability mechanisms have been described theoretically and by numerical simulation, but confirmed by few experimental techniques. In fact, these are mainly based on cameras, which is limited by the imaging resolution, and on light scattering, which is hindered by absorption, reflection, Mie scattering and multiple scattering due to complex air/liquid interfaces during jet break-up. In this communication it is demonstrated that synchrotron small-angle X-ray scattering (SAXS) can give quantitative information on liquid jet dynamics at the nanoscale, by detecting time-dependent morphology and break-up length. Jets ejected from circular tubes of different diameters (100-450 µm) and speeds (0.7-21 m s(-1)) have been explored to cover the Rayleigh and first wind-induced regimes. Various solvents (water, ethanol, 2-propanol) and their mixtures have been examined. The determination of the liquid jet behaviour becomes essential, as it provides background data in subsequent studies of chemical and biological reactions using SAXS or X-ray diffraction based on synchrotron radiation and free-electron lasers.
authors.affiliation: Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9/IV, Graz 8010, Austria.
authors.forename: Benedetta
authors.initials: B
authors.lastname: Marmiroli
authors.affiliation: Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9/IV, Graz 8010, Austria.
authors.forename: Fernando
authors.initials: F
authors.lastname: Cacho-Nerin
authors.affiliation: Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9/IV, Graz 8010, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Sartori
authors.affiliation: Beamline SWING, Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif sur Yvette, France.
authors.forename: Javier
authors.initials: J
authors.lastname: Pérez
authors.affiliation: Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9/IV, Graz 8010, Austria.
authors.forename: Heinz
authors.initials: H
authors.lastname: Amenitsch
keywords: SAXS; break-up length; free liquid micro-jet; jet instability; liquid mixtures; refraction