Photoinduced nucleation: a novel tool for detecting molecules in air at ultra-low concentrations
US6469781B1 · kind B1 · utility
7Cited by
5References
20Claims
0Family size
Assignee
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Key dates
| Filing date | Aug 1, 2000 |
| Grant date | Oct 22, 2002 |
| Priority date | — |
| Expiry date | Apr 4, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2001/2893
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for determining the presence of molecules in a gas at concentrations of less than about 100 ppb. Light having wavelengths in the range from about 200 nm to about 350 nm is used to illuminate a flowing sample of the gas causing the molecules if present to form clusters. A mixture of the illuminated gas and a vapor is cooled until the vapor is supersaturated so that there is a small rate of homogeneous nucleation. The supersaturated vapor condenses on the clusters thus causing the clusters to grow to a size sufficient to be counted by light scattering and then the clusters are counted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.