Multiple-ion-ejection multi-reflection time-of-flight mass spectrometry for single-reference mass measurements with lapping ion species

Abstract

Repeated switching of electric potentials within a single experimental cycle is introduced for a multi-reflection time-of-flight mass spectrometer (also known as an electrostatic ion beam trap) in order to eject different ion species after different storage times. The method is demonstrated with two cluster ions with considerably different mass-to-charge ratios (the A = 624 and 832 isotopologues of Pb3+ and Pb4+, respectively) for the specific case where the sequential ejections result in an identical number of revolution periods. Thus, the ions’ flight lengths are identical, and the resulting time-of-flight values allow single-reference mass determination. The requirements for the switching time window are studied in detail. For the present system and ion pair, the relative mass uncertainty is found to be 3 · 10−7 for short measurements (≈10 min) and 6 · 10−8 for longer ones (≈2 h).

High-Resolution Native Mass Spectrometry

“…In the past decade, developments in ToF instruments have primarily focused on tailoring the electronics for ion-selecting or ion-routing optics and further gas regime control to improve the transmission of high-mass ions. Since high resolution requires increasing the flight distance of ions between the pusher and detector, multiple solutions have recently emerged to improve the mass resolution, including multipass and multireflection instrumental setups. − These recent experimental improvements have led to significant improvements in resolution (>10 000) and mass accuracy (∼5–10 ppm) while simultaneously improving the transmission of high-mass ions and spectral quality in ToF-based native MS. Still, on such instruments the ion signals recorded by native MS remained much broader than would be expected if they were purely limited by the mass resolution of the instrument, resulting often in an overestimation of molecular weights by up to a few percent .…”

Higher Resolution Charge Detection Mass Spectrometry

“…In addition to applications in CDMS, ELITs have been employed as conventional mass spectrometers where the m / z ratios are determined. − In this application, bunches of ions are injected into the trap, and the signal intensity reflects the number of charges in the bunch rather than the charge of single ions. Two configurations have been employed: multireflectron time-of-flight where the ions exit the trap for detection − , and an approach where a ring detector is used to pick up the induced charge from the oscillating ion bunch. − , In both cases, very high m / z resolving powers, in excess of 100 000, have been reported. ,− Such high m / z resolving powers have not yet been achieved in CDMS, partly because the design considerations for these two applications are different. In CDMS, the ELITs are designed for efficient trapping so that single ions can be trapped for long times and the charge can be determined accurately.…”

Chemistry and physics of dopants embedded in helium droplets

“…With manageable voltages in the range of only a few hundred Volts, multiply charged HNDs can be decelerated to a full stop and stored in ion traps. In combination with a multi reflectron TOF‐MS (Benner, 1997; Fischer & Schweikhard, 2020; Wollnik & Przewloka, 1990; Zajfman et al, 1997) a new form of nanocalorimetry becomes possible. For instance, the mass loss by evaporation of He due to the absorption of photons by embedded chromophores or by exothermic chemical reactions triggered by the pickup of reagents can be studied for a long time and with unprecedented precision.…”