Abstract:We present and discuss in detail the design and characterization of a new linear quadrupole ion trap with additional ion ejection and acceleration electrodes that is coupled to a time-of-flight mass spectrometer. Mass spectra of Coulomb crystals consisting of Ca + ,CaO + and CaOH + ions were recorded with a post-ejectionacceleration scheme yielding a mass resolution of m/ m ≈ 700. The second order rate constant for the reaction Ca + + N 2 O → CaO + + N 2 was measured to test the usability of this apparatus for… Show more
“…We can compare our results to other pub- lished results of mass resolutions from radially extracted LIT TOF-MS. As shown in Fig. 6, the resolution from the work of Rø"sch et al 29 is slightly lower than the resolution we obtain, but because of the complexity of their system, they can realize this resolution for only one mass at a time. This is in contrast to our set-up, where high mass resolution is possible for all masses within a mass window greater than 100 amu in a single shot.…”
Trapping molecular ions that have been sympathetically cooled with laser-cooled atomic ions is a useful platform for exploring cold ion chemistry. We designed and characterized a new experimental apparatus for probing chemical reaction dynamics between molecular cations and neutral radicals at temperatures below 1 K. The ions are trapped in a linear quadrupole radio-frequency trap and sympathetically cooled by co-trapped, laser-cooled, atomic ions. The ion trap is coupled to a time-of-flight mass spectrometer to readily identify product ion species and to accurately determine trapped ion numbers. We discuss, and present in detail, the design of this ion trap time-of-flight mass spectrometer and the electronics required for driving the trap and mass spectrometer. Furthermore, we measure the performance of this system, which yields mass resolutions of m/Δm ≥ 1100 over a wide mass range, and discuss its relevance for future measurements in chemical reaction kinetics and dynamics.
“…We can compare our results to other pub- lished results of mass resolutions from radially extracted LIT TOF-MS. As shown in Fig. 6, the resolution from the work of Rø"sch et al 29 is slightly lower than the resolution we obtain, but because of the complexity of their system, they can realize this resolution for only one mass at a time. This is in contrast to our set-up, where high mass resolution is possible for all masses within a mass window greater than 100 amu in a single shot.…”
Trapping molecular ions that have been sympathetically cooled with laser-cooled atomic ions is a useful platform for exploring cold ion chemistry. We designed and characterized a new experimental apparatus for probing chemical reaction dynamics between molecular cations and neutral radicals at temperatures below 1 K. The ions are trapped in a linear quadrupole radio-frequency trap and sympathetically cooled by co-trapped, laser-cooled, atomic ions. The ion trap is coupled to a time-of-flight mass spectrometer to readily identify product ion species and to accurately determine trapped ion numbers. We discuss, and present in detail, the design of this ion trap time-of-flight mass spectrometer and the electronics required for driving the trap and mass spectrometer. Furthermore, we measure the performance of this system, which yields mass resolutions of m/Δm ≥ 1100 over a wide mass range, and discuss its relevance for future measurements in chemical reaction kinetics and dynamics.
“…The tilting angle of the molecular beam apparatus defined a deflection coordinate y for molecules arriving at the trap center. After exposure to the molecular beam for a variable time period, the Coulomb crystals were ejected into a high-resolution time-of-flight mass spectrometer (TOF-MS) 27 for the mass and quantitative analysis of their constituents. Fig.…”
Water is one of the most fundamental molecules in chemistry, biology and astrophysics. It exists as two distinct nuclear-spin isomers, para- and ortho-water, which do not interconvert in isolated molecules. The experimental challenges in preparing pure samples of the two isomers have thus far precluded a characterization of their individual chemical behavior. Capitalizing on recent advances in the electrostatic deflection of polar molecules, we separate the ground states of para- and ortho-water in a molecular beam to show that the two isomers exhibit different reactivities in a prototypical reaction with trapped diazenylium ions. Based on ab initio calculations and a modelling of the reaction kinetics using rotationally adiabatic capture theory, we rationalize this finding in terms of different rotational averaging of ion-dipole interactions during the reaction.
“…This resolution is sufficient to observe the individual isotopes of the trapped molecular ions and has allowed isotopically resolved chemistry and spectroscopy. Several other groups have also recently developed ToFMS capabilities using variations of the technique [66][67][68][69]. In addition to being a powerful measurement capability, we have found that in day-to-day operation the ToFMS provides an incredibly useful diagnostic tool.…”
Section: Detection Tof-ms and Spectroscopymentioning
Sympathetic cooling of molecular ions with ultracold gases is enabling a new era of research in chemistry and physics. There has been much progress in this new field in the last several years and many unanticipated challenges have been overcome. The aim of the present manuscript is to provide a concise review of this work and discuss the way forward for the field.
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