| 摘要 |
<p>A portable analyzer (30) for determining the size and chemical composition of particles suspended in an aerosol. The aerosol is accelerated through a nozzle (42) and skimmers (44, 46), to produce a well-defined beam of particles (60), the speed of which is inversely related to particle size. A dual-beam laser system (70) positioned along the beam path detects light scattered from each particle, to determine the particle's velocity and aerodynamic size. The laser system (70) also triggers a laser (94) to produce a beam that irradiates the particle, to desorb it into its constituent molecules in a source region (88) of a bipolar, time of flight mass spectrometer (90). A mass to charge spectrum of the desorbed molecule is obtained, thereby chemically characterizing the material of the particle. Several features provide sufficient ruggedness to allow the analyzer to be used in the field with minimum calibration and maintenance.</p> |
