Features

This instrument may also be used with a pulsed laser. In this case, the EI ioniser is turned off, and the laser is oriented so that it passes between the extraction lens and the ground plane 10mm away. When the laser is pulsed, it is the laser that initiates the TOF ‘start’, and the extraction lens voltage can be constant. For this scheme the pre-amplifier is switched over to the analogue board (because there are normally copious ions produced per laser pulse). The data acquisition then needs to be analogue, by using a digital ‘scope or an analogue counting card.

The Mini TOF with EI was designed to permit the client to begin work using the EI ioniser, with the intention of adding the pulsed laser at a later stage. The instrument adds on to a client vacuum system, and the client can specify the re-entrant distance of the ionising region to match the experiment. In the event that the pressure is high within the client chamber, a port exists on the side of the TOF spectrometer to permit differential pumping of the detector region.