THE ON-LINE CHEMICAL ANALYSIS OF SINGLE PARTICLES USING AEROSOL BEAMS AND TIME OF FLIGHT MASS SPECTROMETRY |
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Authors: | O Kievit M Weiss P J T Verheijen J C M Marijnissen B Scarlett |
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Affiliation: |
a Delft University of Technology, Faculty of Chemical Technology and Materials Science, Particle Technology Group, Delft, The Netherlands |
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Abstract: | This paper describes an on-line instrument, capable of measuring the size and chemical composition of single, aerosol particles. Possible applications include monitoring aerosol reactors and studying atmospheric chemistry. The main conclusion is that a working prototype has been built and tested. It uses a three stage vacuum system to generate an aerosol beam with a low divergence angle and a high transmittance. The pressure is reduced sufficiently to allow the application of a time-of-flight mass analyzer. The aerosol beam is probed in the analysis section by the focused beam of a low-power helium-neon laser. Every particle crossing the laser beam scatters light, which is detected by two photomultiplier tubes, mounted at angles of 45 and 90°. The signal is stored when both detectors produce a pulse simultaneously, and this event triggers the chemical analysis cycle. A pulsed Nd: YAG laser vaporizes the particle and generates ions, which are next analyzed by a time-of-flight mass spectrometer. In this way combined information on the size and the composition of the particle is obtained. |
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Keywords: | Chemical analysis Photo-ionization Aerosol beam Time-of-flight mass spectrometry |
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