Ion-Trap-Performance Enhancement Utilizing Pulsed Buffer-Gas Introduction

Abstract

A novel means of improving the resolution and total ion signal inside a digitally driven 3D quadrupole ion trap has been studied. Conventional ion-trapping methods occur by injecting helium gas continuously into the trap to kinetically cool ions and improve trapping efficiency. Utilizing a pulsed helium introduction allows for trapping aided by collisional cooling while mitigating ion losses due to gas collisions during ion scan-out. Operating the trap in resonance-ejection mode, we demonstrate that pulsed helium introduction improves the resolution by a factor of ∼2 and that resolution is retained as the total ion signal increases. We also show that ejections at other harmonic secular frequencies under static helium conditions no longer occur during pulsed helium introduction. Improving timing synchronization can lead to the determination of the optimal conditions needed to maximize signal intensity as well as ion ejection.

Enabling Isotope Ratio Measurements on an Ion Trap Mass Spectrometer

“…From our previous work, utilizing pulsed buffer gas introduction increased the trapping efficiency and resolution of the DIT by a factor of 2 . Therefore, coupling the pulsed technique with the improved DAQ could further improve both the measurement precision and accuracy with the theoretically larger sampling capability.…”

“…The instrument and operational conditions used have been described in a previous work, consisting of a square-waveform-driven 3D quadrupole ion trap . Briefly, the ion trap electrodes and the external electron ionization source were removed from a Thermo GCQ, and the corresponding voltages were applied by independent power supply components.…”

“…Briefly, the ion trap electrodes and the external electron ionization source were removed from a Thermo GCQ, and the corresponding voltages were applied by independent power supply components. The current DIT assembly operates in a resonance ejection mode while all experiments are conducted under static-mode buffer-gas conditions (as opposed to pulsed buffer gas introduction) unless otherwise stated . As acquired previously, the ultrahigh purity helium gas was sourced from NexAir and fed through a hydrocarbon/moisture trap (Agilent, HMT200-2) before introduction into the ion trap.…”

“…For instance, Avice et al recently demonstrated a static-mode ITMS that is able to perform high-precision IRMS using a pulse-counting electron-multiplier detection system, with measurement errors of <10 ‰ for xenon isotopes . Additionally, we have studied ITMS utilizing a rectangular trapping waveform, pulsed buffer-gas introduction setup in an analog current-detection mode to improve the ion trapping efficiency and instrument sensitivity . By operating in analog current mode, the averaged ion signals can potentially be optimized through the manipulation of data acquisition systems (DAQs), specifically through the control of x - and y-axis resolutions.…”

Ultrafast infrared spectroscopy with single molecular ions

“…However, the recoil detection techniques needs to be performed under high vacuum conditions, as continuous buffer gas cooling would disturb the detection procedure. Following techniques for selective Buffer gas cooling are available: (i) A pulsed buffer gas source as demonstrated in reference [35] and sketched in figure 2b. (ii) A multizone ion trap with multiple differential vacuum levels, similar to the proposed ion conveyor belt of reference [20], sketched in figure 2c.…”