HARMONIC ENHANCEMENT OF A DETECTED ION-CYCLOTRON RESONANCE SIGNAL BY USE OF SEGMENTED DETECTION ELECTRODES

For certain relaxation mechanisms, FT-ICR mass resolving power increases with harmonic order (e.g., threefold enhancement in mass resolving power for the third harmonic frequency (3omega+) compared to fundamental frequency (omega+)). Moreover, ion cyclotron orbital radius may be determined from the ratio of the magnitude of the 3omega+ signal to that of omega+, M(3omega+)/M(omega+). Unfortunately, the magnitude of the 3omega+ signal from a standard cubic FT-ICR ion trap is small (usually less-than-or-equal-to 10% of the fundamental). In this paper, we present a new theoretical trap design for increasing the 3omega+ content of the detected signal, and we demonstrate experimentally (by measurement of the ICR orbital radius) a wiring configuration which substantially enhances (factor of up to almost-equal-to 5) the 3omega+ signal.