Rovibronic spectroscopy of sympathetically cooled $^{40}$CaH$^{+}$

CaH$^{+}$ is an astrophysically relevant molecule with proposed applications in fundamental physics. We use CaH$^{+}$ co-trapped with Doppler cooled Ca$^{+}$ to perform spectroscopy using two photon photodissociation with a frequency doubled mode locked Ti:Sapph laser. This method was used to measure the vibronic spectrum of the 1$^{1}\Sigma, v = 0 \rightarrow 2^{1}\Sigma, v' = 0, 1, 2, 3$ transition \footnote{R. Rugango, \textit{et al.} \textbf{Chem. Phys. Chem.} 17, 3764–-3768 (2016)}. Measurements of the same transition with the deuterated isotopologue confirmed the assignment and showed an 687 cm$^{-1}$ mismatch with theory \footnote{J. Condoluci, \textit{et al.} article in preparation}. The broad bandwidth of the pulsed Ti:sapph provided an advantage for the initial search for transitions, but did not allow spectral resolution of rotational transitions. Here, we use femtosecond pulse shaping to spectrally narrow the linewidth of the femtosecond laser. This allowed us to obtain rotational constants for the $2^{1}\Sigma, v' = 0, 1, 2, 3$ and $1^{1}\Sigma, v = 0$ states \footnote{A. Calvin, \textit{et al.} article in preparation}.