title: Medium Vacuum Electron Emitter as Soft Atmospheric Pressure Chemical Ionization Source for Organic Molecules.
abstract: An electron emitter as a soft atmospheric pressure chemical ionization source is presented, which operates at inner pressures of the device in the medium vacuum range (>10(-3) hPa). Conventional nonradioactive electron emitters require high vacuum (<10(-6) hPa) to prevent electrical sparkovers. The emitter presented here contains structural modifications of an existing setup, which inhibits electrical breakdowns up to 10(-2) hPa at 8 kV acceleration voltage. The increased inner pressure reduces the ionization efficiency until 10(-3) hPa-achievable without a turbomolecular pump-by 2% compared to high-vacuum conditions. This can be compensated with an increase of the electron source output. The functionality of this ion source is demonstrated with mass spectrometric and ion mobility measurements of acetone, eucalyptol, and diisopropyl methanephosphonate. Additional mass spectrometric measurements of 20 different organic compounds demonstrate the soft characteristics of this ionization source.
authors.affiliation: Leibniz-Institut für Analytische Wissenschaften, Bunsen-Kirchhoff-Strassw 11, 44139 Dortmund, Germany.
authors.forename: Sascha
authors.initials: S
authors.lastname: Liedtke
authors.affiliation: Leibniz-Institut für Analytische Wissenschaften, Bunsen-Kirchhoff-Strassw 11, 44139 Dortmund, Germany.
authors.forename: Norman
authors.initials: N
authors.lastname: Ahlmann
authors.affiliation: Leibniz-Institut für Analytische Wissenschaften, Bunsen-Kirchhoff-Strassw 11, 44139 Dortmund, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Marggraf
authors.affiliation: Leibniz-Institut für Analytische Wissenschaften, Bunsen-Kirchhoff-Strassw 11, 44139 Dortmund, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Schütz
authors.affiliation: Leibniz-Institut für Analytische Wissenschaften, Bunsen-Kirchhoff-Strassw 11, 44139 Dortmund, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Vautz
authors.affiliation: Leibniz-Institut für Analytische Wissenschaften, Bunsen-Kirchhoff-Strassw 11, 44139 Dortmund, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Franzke