Vibronic Spectroscopy of Sympathetically Cooled CaH⁺

Abstract

We report the measurement of the 1 1 Σ −→ 2 1 Σ transition of CaH + by resonance-enhanced photodissociation of CaH + that is co-trapped with laser-cooled Ca + . We observe four resonances that we assign to transitions from the vibrational v=0 ground state to the v =1-4 excited states based on theoretical predictions. A simple theoretical model that assumes instantaneous dissociation after resonant excitation yield results in good agreement with the observed spectral features except for the unobserved v =0 peak. The resolution of our experiment is limited by the mode-locked excitation laser, but this survey spectroscopy enables future rotationally resolved studies with applications in astrochemistry and precision measurement. 1

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

“…If the assignments proposed in Ref. 19 were correct, this study would imply a 150 cm −1 isotopic shift of the electronic energy potential and further evidence the experimentally unobserved transition to the v = 0 state. The isotopic shift of the electronic energy level is large compared to the 10 cm −1 shifts seen in KH.…”

“…Calculation of the Einstein A for each transition gave a dissociation rate, and the total rate at each wavelength was obtained by summing all transitions covered by the laser linewidth. 19 Although the experimental CaD + dissociation is a multi-photon process, we used a first-order model by assuming the dissociation rate is much greater than the first excitation rate. The spectra labeled "Theory" in Fig.…”

Quantum-Logic Detection of Chemical Reactions

“…Via imprint of the motion of a logic ion, the time trajectories and reaction pathways of quenching of rotational state can potentially be studied, and prepare the molecules in the ground-state. Unlike other spectroscopic methods which dissociate the molecules [54], the logic method should be non-destructive.…”

A room-temperature ion trapping apparatus with hydrogen partial pressure below 10−11 mbar

“…The post-processing of the recorded images showed in total 4 reactions. After becoming dark, the ion always stayed in nonfluorescing state on a timescale of minutes, namely for 63.5 s, 934.5 s, 506 s and 366.5 s and then became bright again, which can be most likely attributed to an off-resonant optical dissociation 22 . The time-lapse images were processed one by one by averaging the photon counts from pixels surrounding the ion image for each ion separately.…”

“…For thoroughly cleaned and wellbaked chambers pre-pumped with a turbomolecular pump, a) Electronic mail: slodicka@optics.upol.cz the limiting residual element with highest partial pressure corresponds to a hydrogen due to its large concentration in stainless steel and high diffusion rate 17 . The chemical reactions of hydrogen with various atomic ion species were formerly studied due to their creation feasibility and suitability for studies of ultracold ion chemistry 18,19 , direct or sympathetic laser cooling [20][21][22][23][24] , proposed as sensitive probes of fundamental theories 25 , or considered as astrophysically important molecules 26 .…”