Photoelectron source for use in a gas chromatograph detector and mass spectrometer ion source

An ionization source is disclosed for use with mass spectrometers and electron capture species detectors having an ionization light source excited so as to illuminate a fluid sample which flows past the light source whereby electrons are photoelectrically generated by a light source. Means are also provided to accelerate the photoelectrons and to extract heavy ions generated by the accelerated photoelectrons from the fluid sample. Further means are provided to focus the extracted heavy ions so that they may be detected. Also included is a means to maintain a vacuum between the light source and the sample and the detector