Time-of-Flight (ToF) Mass Analyzers

The basic principles of mass analysis using time-of-flight mass analyzers are relatively straightforward in comparison to many of the other typical mass analyzing devices. Ions are extracted (or produced) in short bursts or packets within the ion source and subjected to an accelerating voltage. These ions then drift or fly down an evacuated tube of set length.

There are no complicated ion focusing devices necessary to constrain the ions to a particular flight path and as such the ions pass in a straight line, at constant speed towards the detector where a plot of abundance against time-of-flight may be recorded. The flight times are correlated against at least two known masses from an infused tune compound allowing a simple conversion to obtain a typical abundance versus mass-to-charge (m/z) spectrum. This modules explores the theory and working principles of time-of-flight mass analyzers.

Topics include:

• Time-of-flight (ToF) mass analyzers
• ToF - equations of motion
• ToF resolution
• ToF - the reflectron
• ToF increased resolution using reflectrons
• ToF - performance limitations
• Orthogonally accelerated ToF instruments
• oaToF pusher electrode
• oaToF pusher pulse rate
• oaToF deflecting voltage
• oaToF interfacing details
• oaToF mass resolution and accuracy
• oaTof dynamic range