Electrospray

from Wikipedia, the free encyclopedia
Electrospray, close-up in the area of ​​the atomizing nozzle

Electrospray is the name for a process for atomizing liquids with the help of an electric field . The resulting spray contains fine, highly unipolar charged drops with a narrow size distribution. The physical principle is based on the instability of a Taylor cone .

The field strength required to atomize the liquid is relatively high and strongly dependent on the electrical conductivity and the surface tension of the liquid. If the conductivity and / or the surface tension of the liquid is very high, a partial discharge ( corona discharge ) or a complete discharge of the ambient gas can occur before the liquid begins to atomize.

Electrolytic liquids are usually atomized under atmospheric conditions (e.g. in ambient air). Examples of use here are e.g. B. electrostatic surface coatings (painting, corrosion protection, medical inhalation aerosols) or analytical devices ( mass spectrometer ). Significantly higher field strengths can also be used in a vacuum without a gas discharge occurring. This is used to z. B. to generate metal ions with high energy for ion etching or for ion drives in satellites.

In laboratory tests, low-melting metals ( solder , Wood's metal , gallium and indium ) have also been dispersed in a gaseous environment in order to produce fine, monodisperse metal particles and granular films on surfaces. The very high electrical field strengths required, however, require the use of electronegative gases (electrical extinguishing gases, e.g. sulfur hexafluoride , SF 6 ) with increased pressure in order to prevent premature gas discharges before atomization begins.

See also

Web links

Commons : Electrospray ionization  - collection of images, videos and audio files

Individual evidence

  1. ^ Geoffrey Taylor: Disintegration of Water Drops in an Electric Field . In: Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences . tape 280 , no. 1382 , June 28, 1964, pp. 383-397 , doi : 10.1098 / rspa.1964.0151 .
  2. ↑ Richard G. Forbes, Neboysha N. Ljepojevic: Liquid metal ion source theory: electro hydrodynamics and emitter shape . In: Surface Science . tape 266 , no. 1-3 , March 15, 1992, pp. 170-175 , doi : 10.1016 / 0039-6028 (92) 91016-5 .
  3. ↑ M. Lohmann, H. Kirsch, A. Schmidt-Ott: Production of metallic particles via electrostatic atomization of metallic particles via electrostatic atomization of liquid metals . In: J. Schwedes, S. Bernotat (Ed.): Fine Solid Particles . Shaker Verlag, Aachen 1997, ISBN 3-8265-3050-0 , p. 152 .