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

Abstract

We observe vibronic transitions in CaD + between the 1 1 Σ and 2 1 Σ electronic states by resonance enhanced multiphoton photodissociation spectroscopy in a Coulomb crystal. The vibronic transitions are compared with previous measurements on CaH + . The result is a revised assignment of the CaH + vibronic levels and a disagreement with CASPT2 theoretical calculations by approximately 700 cm −1 .

Second-Scale $^9\text{Be}^+$ Spin Coherence in a Compact Penning Trap

“…Future experiments could elucidate the previously-observed 9 Be + clock accuracy limit of 1 × 10 −13 , which Bollinger and co-authors attributed to collisions with background CH 4 molecules [7]. Furthermore, an alternative clock species such as 43 Ca + (I = 7/2) would mitigate reactive ion loss [26] and provide clock transitions at higher trap magnetic field.…”

“…40 Ca + SPECTROSCOPY Trapped 40 Ca + is useful for characterizing the Penning trap magnetic field environment due to the high sensitivity (∼ 28.025 MHz/mT) of its |S 1/2 , +1/2 → |S 1/2 , −1/2 electronspin resonance (ESR) transition [36]. Also, in contrast to Be + and Mg + , Ca + does not exhibit long-term loss from chemical reactions with residual H 2 molecules [26,37]. We regularly maintain a 40 Ca + crystal for weeks.…”

“…In this article, we report the first Rabi and Ramsey spectroscopy measurements of 9 Be + using co-trapped 40 Ca + as a sympathetic coolant. Unlike with Be + or Mg + , chemical reactions between Ca + and background H 2 are naturally reversed under illumination by the Ca + Doppler cooling light [26]. We measure a 9 Be + spin coherence duration of > 1 s under ambient conditions by operating near the 0.6774-T magneticfield-insensitive (MFI) transition.…”

Rovibronic Spectroscopy of Sympathetically Cooled 40CaH+

“…Optimized parameters for the experimental spectroscopic constants for the excited states are compared to ab initio [11] theoretical parameters for the predicted spectrum. The λ(v ) term is the v = 0, J = 0 → v , J = 0 transition.…”

“…As an example, CaH was identified in sunspots over a century ago [5], yet endothermic reactions of Ca + in the ground state with H 2 [6] hindered the spectroscopy of the molecular ion. Spectroscopy of this molecular ion was only recently performed in Coulomb crystals with the measurement of a dissociative transition [7], two vibrational overtones [8], non-destructive state detection [9], finally the vibronic [10,11] and rovibronic [12], transitions discussed in this thesis. Trapping molecular ions in a Coulomb crystal allows a high degree of localization and long storage times that enable the observation of weak transitions on as few as single ions.…”