초록 ▼

A system is provided for analyzing the particles in aerosols, as in making air pollution studies, which enables the making of rapid chemical analyses of particles. The system includes an apparatus for producing a controlled stream of individual particles to be analyzed from an environment, and an ap

A system is provided for analyzing the particles in aerosols, as in making air pollution studies, which enables the making of rapid chemical analyses of particles. The system includes an apparatus for producing a controlled stream of individual particles to be analyzed from an environment, and an apparatus for vaporizing and ionizing the particles while they move in free flight, for analysis by a mass spectrometer. The apparatus for producing a stream of particles includes a capillary tube through which the air with suspended particles moves, a skimmer device having a small opening spaced from an end of the capillary tube to receive particles passing through the tube, and a vacuum pump for pumping air out of the space between the tube and skimmer. The vacuum pump serves to remove much of the gas from around the particles, while also creating an inflow of air and particles through the capillary tube. The particles passing through the skimmer opening can be simultaneously vaporized and ionized while in free flight, by a laser beam of sufficient intensity that is directed across the path of the free flying particles.

대표청구항 ▼

1. Apparatus for analyzing liquid or solid particles comprising: means for passing individual particles to be analyzed that each have a mass that is a plurality of orders of magnitude greater than the mass of molecules in air, in free flight past a predetermined path location; means for directin

1. Apparatus for analyzing liquid or solid particles comprising: means for passing individual particles to be analyzed that each have a mass that is a plurality of orders of magnitude greater than the mass of molecules in air, in free flight past a predetermined path location; means for directing a light beam across said location, with an intensity to heat a particle sufficiently to vaporize and ionize it; and mass spectrometer means located near said path location for analyzing the ions resulting from the particle vaporization and ionization. 2. The apparatus described in claim 1 including: means for directing particles rapidly along a path which includes said path location; and means for detecting the presence of a particle at a position upstream from said path location; and wherein said means for directing a light beam includes means responsive to the detection of a particle by said detecting means, for generating a light pulse at a time after said detecting means detects a particle. 3. A method for analyzing solid or liquid particles in a gas stream of gas molecules, where the particles each have a mass which is orders of magnitude greater than that of said gas molecules, comprising: passing said particles along a predetermined path free of support from a substrate; applying electromagnetic radiation to at least one particle while it passes along said path, at an intensity high enough to vaporize and ionize it; and detecting the ions generated from the vaporized particle. 4. The method described in claim 3 including: detecting individual particles passing a predetermined location along said path, and applying said radiation in a brief pulse to the detected particle upon its detection. 5. A method for analyzing solid or liquid particles in a gas stream, where each particle has a mass that is a plurality of orders of magnitude greater than the mass of each gas molecule comprising: passing said particles along a predetermined path free of support from a substrate, to a heated body which is hot enough to vaporize the particle; directing a stream of ionizing electrons at the vapor to ionize it; and detecting the resulting ions. 6. The method described in claim 5 including: detecting individual particles passing a predetermined location along said path, and applying said radiation in a brief pulse to the detected particle upon its detection. 7. Apparatus for analyzing solid or liquid particles generally on the order of one micron diameter, that are entrained in a gas, comprising: means for passing said particles in free flight along a predetermined path; means for vaporizing and ionizing at least one of said particles while it passes along said path, including means for applying electromagnetic radiation of an intensity to vaporize the particle while it remains in free flight; and means for detecting the ions generated from the vaporized particle. 8. The apparatus described in claim 7 wherien: said means for applying radiation applies radiation of an intensity on the order of 10 9 watts per square centimeter. 9. The apparatus described in claim 7 including: means for detecting the presence of a particle at a location along said path, and means responsive to said detecting means for operating said radiation applying means to deliver a pulse of optical radiation. 10. Apparatus for analyzing solid or liquid particles generally on the order of one micron diameter, that are entrained in a gas, comprising: means for passing said particles in free flight along a predetermined path; means for vaporizing and ionizing at least one of said particles while it passes along said path, including a heated body located along said path for vaporizing said particles, and an electron source aimed to apply electrons to a location near said heated body to ionize the vapor; and means for detecting the ions generated from the vaporized particle. 11. In apparatus for analyzing particles entrained in a gas, wherein the particles each have a mass which is orders of magnitude greater than the mass of each of the molecules of said gas, the improvement of means for providing a stream of particles, comprising: a narrow tube having a length which is a plurality of times greater than its inside diameter, said tube having an entrance end for receiving gas with particles entrained therein, and an exit end; a skimmer having a narrow opening spaced from but aligned with said narrow tube, to receive particles moving in a largely straight path from said tube to said skimmer; a housing surrounding the region between said narrow tube and said skimmer, and forming said region with a cross-section much larger than the cross-section of said tube, to permit the dispersion of gas therein to minimize the amount of gas reaching said skimmer opening; means for evacuating gas from said region; and means for applying optical radiation to a path location which lies beyond an end of said skimmer which is opposite said tube, in an intensity to ionize and vaporize free particles moving past said path location, and means for detecting the resulting ions. 12. In apparatus for analyzing particles entrained in a gas, wherein the particles each have a mass which is orders of magnitude greater than the mass of each of the molecules of said gas, the improvement of means for providing a stream of particles, comprising: a narrow tube having a length which is a plurality of times greater than its inside diameter, said tube having an entrance end for receiving gas with particles entrained therein, and an exit end; a skimmer having a narrow opening spaced from but aligned with said narrow tube, to receive particles moving in a largely straight path from said tube to said skimmer; a housing surrounding the region between said narrow tube and said skimmer, and forming said region with a cross-section much larger than the cross-section of said tube, to permit the dispersion of gas therein to minimize the amount of gas reaching said skimmer opening; means for evacuating gas from said region; and means for applying sufficient heat to particles moving past a path location beyond an end of said skimmer which is opposite said tube, to vaporize the particles, and means for applying an electron stream to a location at least near said path location to ionize the vapor.