Reassigning the CaH$^+$ 1$^{1}\Sigma\rightarrow$ 2$^{1}\Sigma$ vibronic transition with CaD$^+$

Abstract

We observe vibronic transitions in CaD$^+$ between the 1$^{1}\Sigma$ and 2$^{1}\Sigma$ 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$^{-1}$.