Improved Miniaturized Linear Ion Trap Mass Spectrometer Using Lithographically Patterned Plates and Tapered Ejection Slit

Abstract

We present a new two-plate linear ion trap mass spectrometer that overcomes both performance-based and miniaturization-related issues with prior designs. Borosilicate glass substrates are patterned with aluminum electrodes on one side and wire-bonded to printed circuit boards. Ions are trapped in the space between two such plates. Tapered ejection slits in each glass plate eliminate issues with charge build-up within the ejection slit and with blocking of ions that are ejected at off-nominal angles. The tapered slit allows miniaturization of the trap features (electrode size, slit width) needed for further reduction of trap size while allowing the use of substrates that are still thick enough to provide ruggedness during handling, assembly, and in-field applications. Plate spacing was optimized during operation using a motorized translation stage. A scan rate of 2300 Th/s with a sample mixture of toluene and deuterated toluene (D8) and xylenes (a mixture of o-, m-, p-) showed narrowest peak widths of 0.33 Th (FWHM). Graphical Abstract ᅟ.

Double resonance ejection using novel radiofrequency phase tracking circuitry in a miniaturized planar linear ion trap mass spectrometer

“…The timing control of the double resonance experiments was comparable with that in previous experiments performed without double resonance ejection, except that the RF amplitudes during ionization and ion cooling were 225 V 0‐p and 175 V 0‐p , respectively. This was done to increase the depth of the potential well during ionization.…”

“…Ultimately, the main motivation behind switching to double resonance ejection was to increase the SNR. A comparison of optimized AC resonance ejection and optimized double resonance ejection using the PLIT can be seen in Figure . The SNR of the AC resonance experiments in Figure was calculated by dividing the amplitude of the largest peak by the amplitude of the noise.…”

“…Because of the non‐linear energy uptake from the multipole resonance, double resonance ejection has been shown to increase the peak intensity and resolution of a mass spectrum because the ions eject in a smaller time window . Although it has been shown that higher‐order multipoles in a coplanar trap can be adjusted, for our experiments we decided to use the intrinsic β = 2/3 hexapole resonance in order to remain consistent with previous experiments …”

Optimal fabrication methods for miniature coplanar ion traps

“…The parameters were as follows: an RF driving frequency of 1.35 MHz, an RF amplitude of 200 to 560 V0‐p, an AC frequency of 620 kHz, an AC amplitude of 1 V0‐p, a DC endbar voltage of 5 V, and a plate spacing of 5.0 mm. Additional details regarding operation and performance characteristics of the trap can be found in previous publications . Figure is an average of 20 scans showing better than unit resolution for the major peaks at m / z 91, 92, 98, and 100.…”

Analysis of Multipolar Linear Paul Traps for Ion–Atom Ultracold Collision Experiments

“…The key question of interest here is whether higher order multi-pole traps (Figure 1) are more favorable than a quadrupole trap or not, if the objective is to study the ion-atom collisions at the coldest temperatures. The wider scope of such traps ranges from single ion-based mass spectroscopy to optical spectroscopy experiments [23][24][25][26][27] and a few ion-based quantum logic and computation experiments [28,29], experiments with coulomb crystals with many ions [9,10,[30][31][32][33] and single ions or ion clouds interacting with cold atoms [7,10,[13][14][15][34][35][36][37].…”