An
electrostatic linear ion trap (ELIT) has been configured to
allow for the simultaneous acquisition of mass spectra via Fourier
transform (FT) techniques (frequency measurement) and via time-of-flight
(TOF; time measurement). In the former case, the time-domain image
charge derived from a pick-up electrode in the field-free region of
the ELIT is converted to frequency-domain data via Fourier transformation
(i.e., FT-ELIT MS). In the latter case, the time difference between
ion injection into the ELIT and ion detection after release from the
ELIT using a microchannel plate (MCP) enables the acquisition of multireflection
time-of-flight mass spectra (MR-TOF MS). The ELIT geometry facilitates
the acquisition of both types of data simultaneously because the detection
schemes are independent and do not preclude one another. The two MS
approaches exhibit a degree of complementarity. Resolution increases
much faster with time with the MR-TOF approach, for example, but the
closed-path nature of executing MR-TOF in an ELIT limits both the <i>m</i>/<i>z</i> range and the peak capacity. For this
reason, the FT-ELIT MS approach is most appropriate for wide <i>m</i>/<i>z</i> range applications, whereas MR-TOF
MS can provide advantages in a “zoom-in” mode in which
moderate resolution (<i>M</i>/Δ<i>M</i><sub>fwhm</sub> ≈ 10000) at short analysis times (10 ms) is desirable