ETF15 Combined Electron TOF / Positive Ion Mass Spectrometer
Features:
- The bipolar setup allows to use the spectrometer either as a electron tof spectrometer with time-of-flight resolution T/ΔT > 100 or as a sensitive time-of-flight mass spectrometer with mass resolution M/ΔM > 300
- Minimum electron energy ca. 20 eV (depending on the magnetic fields of the environment)
- Fieldfree drift tube with ca. 350 mm standard length, encapsulated in a µ-metal shield
- In “electron mode” the drift tube can be floated to positive or negative potentials:
up to –180 V for decelerating fast electrons
up to +180 V for accelerating slow electrons to reduce the effect of magnetic fields - Channelplate detector with two-stage chevron geometry, channelplates with 5 µm pore size for fast response times, 40 mm active diameter
- Post-acceleration stage in front of the detector to get a uniform sensitivity for all electrons irrespective of their kinetic energy and to reduce the effects of magnetic fields penetrating through the back flange into the µ-metal shield
- Only completely non-magnetic materials are used for the spectrometer, most of the parts including the drift tube and all screws are made from titanium
- The electron beam entering through the entrance aperture is collimated in an extraction module, the acceptance angle (full angle) is ca. 30°. The only connection between the ionisation chamber and the tof chamber is the entrance aperture which allows to pump the tof spectrometer differentially
- The vacuum chamber of the electron spectrometer is manufactured from non-magnetic stainless steel 1.4429 (equivalent to 316 LN). It consists of a 6” o.d. conflat (CF100) connection flange, a 6” o.d. conflat (CF100) pump flange (CF100) and a 2.75” o.d. conflat flange (CF38) for pressure metering
- High voltage power supply in a 19” box, 3HE (132 mm) high, 500 mm deep. All the polarities of the high voltages are reversed with a single switch
Ion source of combined electron /ion tof spectrometer ETF15. In “electron mode”, the ionisation occurs under fieldfree conditions. In “mass spectrometer mode”, the ions are created in a homogenous extraction field between repeller and extraction electrode and are subsequently accelerated in a second acceleration stage to their pass energy (ca. 2000 eV) according to the Wiley-McLaren criterion. The laser focus is always on ground potential to enable gas capillary inlet.
Options of the ETF15 spectrometer:
- Drift tube length other than standard length of 350 mm
- Distance between tof connection flange and laser focus other than standard length of 354 mm