Selective photo-ionization detector using ion mobility spectrometry
US6509562B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 16, 1999 |
| Grant date | Jan 21, 2003 |
| Priority date | — |
| Expiry date | Sep 16, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/622
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A photo-ionization detector (PID) employs combinations of ion mobility spectrometry, ionization energy discrimination, and chemical filtering to identify the presence and quantity of specific gases. One such PID introduces a gas sample into an ionization chamber at an end of a drift tube. UV light from a PI source ionizes ionizable molecules contained in the gas sample. The PI source includes either multiple UV lamps, each having a specific energy level for discriminating between potential constituents of the gas sample or one multiple-energy level UV lamp with different light bandwidth window zones and a zone selector. A shutter grid separates the ionization chamber from the drift tube. When the shutter grid is open, an electric field in the drift tube attracts ions that travel against the flow of a drift gas until a collector electrode at the end of the drift tube captures the ions. A time required for the ions to travel the length of the drift tube is characteristic of the type of ion. Thin mesh electrodes in the drift tube sustain a uniform electric field so that groups of ions traveling down the drift tube to create well defined current pulses at the collector electrode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.