An electrospray ionization source for generating aerosols in the nanometer size range
- Lawrence Berkeley Lab., CA (United States)
We have used electrospray ionization to create an aerosol of 26 nm microspheres from a colloidal suspension. Nebulization of a dilute suspension of particles followed by drying of the spray is a well known technique for generating an aerosol with a size distribution very similar to that of the particles. However, if a liquid containing colloidal particles smaller than a few hundred nanometers is nebulized, non-volatile solutes can add mass to the final residue particle, thereby altering the size distribution of the original particles. Electrospray nebulization offers one means to extend the approach to smaller colloid sizes by generating droplets with diameters similar to that of the suspended particles, thus minimizing the residue contribution. Rosell and De la Mora demonstrated the method with 300 nm particles, and predicted that electrosprays could be used to nebulize suspensions of much smaller particles. An aerosol generated by electrospraying a mixture of 100, 50 and 26 nm fluorescent polystyrene-latex microspheres yielded three sharply defined concentric rings on an impaction plate after passing through an aerodynamically focusing nozzle. The presence of three rings confirms the expected, tri-modal size distribution of the aerosol because the diameter of a ring deposit from an aerodynamically focused aerosol beam is directly related to particle size. Direct inspection of the deposits with an epi-fluorescence microscope revealed the relative size of the particles comprising each ring. We also noticed that the distribution of particles in the spray region is highly non-uniform and can vary dramatically from that of the droplets. This observation implies that sampling particles from an arbitrary portion of an electrospray plume can easily misrepresent the average particle flux in the spray.
- OSTI ID:
- 166575
- Report Number(s):
- CONF-9510126-; TRN: 95:008181-0066
- Resource Relation:
- Conference: Annual meeting of the American Association for Aerosol Research, Pittsburgh, PA (United States), 9-13 Oct 1995; Other Information: PBD: 1995; Related Information: Is Part Of American Association for Aerosol Research (AAAR) `95; PB: 464 p.
- Country of Publication:
- United States
- Language:
- English
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