Probing Isotope Effects in Chemical Reactions Using Single Ions

Abstract

Isotope effects in reactions between Mg+ in the 3p{2}P{3/2} excited state and molecular hydrogen at thermal energies are studied through single reaction events. From only approximately 250 reactions with HD, the branching ratio between formation of MgD+ and MgH+ is found to be larger than 5. From an additional 65 reactions with H2 and D2 we find that the overall fragmentation probability of the intermediate MgH2+, MgHD+, or MgD2+ complexes is the same. Our study shows that few single ion reactions can provide quantitative information on ion-neutral reactions. Hence, the method is well suited for reaction studies involving rare species, e.g., rare isotopes or short-lived unstable elements.

Design and characterization of a linear quadrupole ion trap for high-resolution Coulomb-crystal time-of-flight mass spectrometry

“…The mass-to-charge ratio of the ionic reaction products can be determined by resonant-excitation mass spectrometry (REMS) [8,11,12]. REMS works best on small Coulomb crystals consisting of one single atomic or molecular ion that is sympathetically cooled by one laser cooled ion enabling the distinction of isotopes that differ by only one atomic mass unit (u) [12,13]. However, for larger mixed-species Coulomb crystals the REMS spectra become complex due to Coulomb coupling [14] and an unambiguous mass assignment is not always possible [15,16].…”

Quantum-defect theory for−1/r4-type interactions

“…Renewed interest in QDT for −C 4 /r 4 polarization potential has arisen with the emergence of cold ion-atom [11][12][13][14][15][16][17][18][19][20] and ion-molecule interactions and reactions [21][22][23][24][25][26]. For such heavier systems, the QDT takes on a different magnitude of importance for three primary reasons.…”

Reassigning the CaH+ 11Σ → 21Σ vibronic transition with CaD+

“…1-5 Cold ionic ensembles in a variety of platforms have proved useful for astrochemical identification [6][7][8] and studies of internal state distributions, 3,9 while co-trapping with Doppler-cooled ions offers advantages for probing the possible time variation of fundamental constants, [10][11][12] and performing quantum logic spectroscopy. [13][14][15][16] Ionic metal-hydrides like CaH + and MgH + are promising candidates for these applications 17 due to their large rotational constants and Doppler-cooled dissociation products.…”