Laser-assisted particle analysis

摘要

The present invention provides methods and apparatus for analyzing the particulate contents of a sample such that a high proportion of the sample particles are analyzed without discrimination against high electronegativity and high ionization potential elements. In an exemplary embodiment, the invention comprises an apparatus for analyzing the particulate content of a sample having particulate diameters in the range of 0.001-10 microns. The apparatus comprises an evacuable chamber equipped with a chamber entrance through which a particle-laden gas stream enters. An inlet device, such as a capillary, communicates with the chamber entrance for inputting the particle-laden gas stream to the evacuable chamber. A laser is positioned to produce a focused laser beam which intersect the particle-laden gas stream at position approximately 0.1 mm from the chamber entrance. The laser beam has a power density sufficient to fragment and ionize particles entrained within the particle-laden gas stream. A detector is positioned to detect the ionized species produced by the laser. The laser beam is focused so that the beam has a cross-sectional area in the plane of intersection between the particle-laden gas stream and the laser beam that is at least as large as the cross-sectional area of the particle-laden gas stream in the plane of intersection. In one embodiment, the lens is a set of two cylindrical lenses.