Loading patent…
AssigneeDeutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V.
InventorsHorst-Henning Grotheer, Harald Oser, Reinhold Thanner
Estimating the term…
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.
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 and detected in the mass spectrometer, characterized in that a continuum zone of the stream of carrier gas where the temperature of the carrier gas decreases with increasing distance (x) from an outlet aperture of the nozzle, a molecular beam zone of the stream of carrier gas where the temperature of the carrier gas essentially decreases no further with increasing distance (x) from the exit aperture of the nozzle, and a boundary between the continuum zone and the molecular beam zone are determined and that the sample molecules are ionized in an ionization zone near to the boundary between the continuum zone and the molecular beam zone.
Apparatus for detecting sample molecules in a carrier gas, comprising a nozzle for generating a divergent stream of carrier gas by means of expansion of the carrier gas into a vacuum, a means for the selective ionization of the sample molecules to form sample molecule ions in an ionization zone of the stream of carrier gas by absorption of photons, a mass spectrometer and a means for generating an electrical pulling field drawing the sample molecule ions into the mass spectrometer with a pulling electrode, characterized in that the ionization zone (126) is arranged near to a boundary determined for the stream of carrier gas (120) between a continuum zone (122) determined for the stream of carrier gas (120) where the temperature of the carrier gas decreases with increasing distance (x) from an exit aperture (44) of the nozzle (40) and a molecular beam zone (124) determined for the stream of carrier gas (120) where the temperature of the carrier gas essentially decreases no further with increasing distance (x) from the exit aperture (44) of the nozzle (40).
Dependencies are inferred from the claim text.