2.2 Time pattern
The typical measurement cycle is as follows: First,
ions are generated by atmospheric
pressure ionization and introduced into the instrument through the
capillary inlet. In the API region, the diameter of the ion beams can be
reduced to the submillimeter range by collision action in the RFQs.
Then, the ions are transferred to the FLT and trapped by the voltage of
the endcaps switched up. After a final cooling in the FLT,
the ions are ejected
orthogonally, accelerated by the AC, and ion-optically adjusted by the
ST and DT. Finally, the ions
enter the MRTOF analyzer and reflect back and forth, increasing the ion
flight distance from meters to hundreds of meters or even kilometers.
After a predetermined number of
reflections, the ejection endcap
switches down and allows the ions travel to a micro-channel plate ion
detector (MCP, R3809U, Hamamatsu). The timings for the FLT ejection and
both mirror endcaps switching are
mass dependent (as shown in Fig. 2), thus requiring a precalculated
timing pattern.