Using controlled ion extraction to combine a ring electrode trap with a reflectron time-of-flight mass spectrometer

Room-Temperature Methane Activation Mediated by Free Tantalum Cluster Cations: Size-by-Size Reactivity

“…Selected fractions of reactive gas (that is, methane), in the buffer gas lead to reactions of the trapped clusters under multicollision conditions. After a specified storage time, a controlled ejection transports charged clusters and reaction products out of the RET into a home-built reflectron time-of-flight mass spectrometer that determines the mass-to-charge ratio ( m / z ) and abundance of all species. By systematic variation of the storage time, the progression of the reaction is recorded.…”

“…The fitting parameters obtained from the simulation are rate coefficients of pseudo-first order ( k (1) ) for each reaction step and normalization to the methane particle density [CH 4 ] or the product of methane and helium particle density [He] results in bimolecular k (2) or termolecular rate coefficients k (3) , respectively (see eq ). Due to differential pumping of the RET from the axial openings and injection of the buffer gas via a channel into the center of the trap, there is an unknown pressure gradient throughout, and the locally measured pressure deviates from the mean value in the RET . To remedy this finding, which usually leads to a rather large uncertainty of the absolute value for the rate coefficients, the obtained rate coefficient for [TaCH 2 ] + formation is compared to a literature reference, and the corresponding ratio is used as a correction factor for all experimentally determined rate coefficients (see section S1 in the Supporting Information).…”

“…Ion-guiding elements transfer the resulting cluster beam into a quadrupole mass filter (Model 5221, Extrel), which facilitates the selection of a single cluster size. Size-selected clusters are subsequently guided into a home-built, temperature-controllable ring electrode ion trap (RET) 40 adapted from the designs of Gerlich 41 and Goebbert et al 42 A steady stream of helium buffer gas (He 6.0, Westfalen) into the RET is regulated by a mass flow controller (500 sccm range, MKS), and the resulting pressure of 0.77 Pa is monitored by a baratron (model 722B, MKS).…”

Thermal Dehydrogenation of Methane Enhanced by μ2-Oxo Ligands in Tantalum Cluster Cations [TaxO]+, x = 4, 5

“…Clusters with small rotational and vibrational temperatures (of 5–120 and 50–325 K, respectively) are typically generated in similar ablation sources. − The cluster beam is guided by various ion optics into a quadrupole mass filter (model 5221, Extrel), which selects ions of a single mass, while the remainder is suppressed. Generally, a size-selected cluster beam generated by a single shot of the ablation laser is collected (within ∼5 ms) and stored for a specified reaction time in a homebuilt ring-electrode ion trap. , When the clusters initially enter the ion trap, their excess kinetic energy is quickly dispersed via collisions with the buffer gas (He 6.0, Westfalen) and solely ions with a sufficiently low energy are successfully stored. A constant stream of buffer gas facilitates a total pressure of 0.77 Pa inside the trap, which causes approximately 100 collisions of the clusters with the buffer gas per millisecond.…”

Stacked-Ring Ion Guide for Cooling and Bunching Rare Isotopes

“…"Digital", i.e. rectangularly shaped, RF potentials have recently received much attention [33,34,35,36,37,38,39], as they provide stronger transverse confinement and facilitate adaptation across a broad frequency band [11].…”