Process and apparatus for detecting sample molecules in a carrier gas

US5629518A · kind A · utility

Assignee

• Deutsche Forschungsanstalt Fur Luft-Und Raumfahrt E.V. · DE

Inventors

• Horst-Henning Grotheer · Stuttgart, DE
• Harald Oser · San Carlos, US
• Reinhold Thanner · Stuttgart, DE

Key dates

• Filing date: Nov 22, 1995
• Grant date: May 13, 1997
• Expiry date: Nov 22, 2015

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01J49/40
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

In order to improve a process for detecting sample molecules in a carrier gas, wherein a divergent stream of carrier gas is generated by means of expansion of the carrier gas through a nozzle into a vacuum, the sample molecules are ionized selectively to form sample molecule ions in an ionization zone of the stream of carrier gas by absorption of photons and the sample molecule ions are drawn by an electrical pulling field into a mass spectrometer, such that the sensitivity of the process is distinctly increased without forfeiting selectivity, it is suggested that a continuum zone of the stream of carrier gas, in which the temperature of the carrier gas decreases with increasing distance from an exit aperture of the nozzle, a molecular beam zone of the stream of carrier gas, in which the temperature of the carrier gas does not essentially decrease any further with increasing distance from the exit aperture of the nozzle, and a boundary between the continuum zone and the molecular beam zone be determined and that the sample molecules be ionized in an ionization zone near to the boundary between the continuum zone and the molecular beam zone.