Schematic of the quadrupole-MRT instrument and the MRT analyzer.
(a) The overall instrument design is “Q-TOF-like” with
ions introduced in the source being focused onto the main axis via
a StepWave ion guide and through a quadrupole followed by a segmented
quadrupole collision cell. (b) Ions from the focusing optics are (1)
pushed downward (−X) so that the combination
of the push voltage and the ion’s +Y velocity
results in a trajectory of 6° from vertical (X axis) . The mirrors are inclined in X at 3°,
so the ion path is further rotated, at (2), with a retarding field
in Y. This aligns the X path rotation
with the center line of the mirrors. The ions are then deflected in Z, at (3), which provides the drift across the mirrors.
After each reflection in X, the ions pass through
a periodic lens, which compensates for beam expansion in Z. (c) The element P1 defines the ion beam angle into the mirrors,
and P23 is arranged so that it reflects the ion beam back into the
mirrors, which has the effect of doubling the flight length compared
with positioning the detector at P23. In this arrangement, the effective
flight length is ∼48 m. P1 can be operated independently to
shorten the flight path (Figure S1).