LABORATORY DETECTION OF VIBRATION-ROTATION TRANSITIONS OF 12CH+ AND 13CH+ AND IMPROVED MEASUREMENT OF THEIR ROTATIONAL TRANSITION FREQUENCIES

The elusive C-H vibration-rotation transitions of the fundamental ions $^{12}$CH$^+$ and $^{13}$CH$^+$ have been observed for the first time in the laboratory. The technique of state-dependent attachment of He atoms to these ions in a cryogenic trap\footnote{O. Asvany, S. Br\"unken, L. Kluge, and S. Schlemmer 2014, Appl. Phys. B, 114, 203-211.} has been used to obtain high-resolution rovibrational data. The excitation source is an IR OPO whose frequency is measured using a frequency comb. In addition, the lowest frequency rotational transitions of $^{12}$CH$^+$, $^{13}$CH$^+$ and $^{12}$CD$^+$ have been revisited\footnote{S. Yu, B. J. Drouin, J. C. Pearson and T. Amano 2015, in Contribution RD06, 70th International Symposium on Molecular Spectroscopy.}$^,$\footnote{T. Amano 2010, Astrophys. J. Lett., 716, L1.}$^,$\footnote{S. Br\"unken, L. Kluge, A. Stoffels, J. P\'erez-R\'{\i}os, and S. Schlemmer 2017, J. Mol. Spec. 332, 67.} using a synthesizer and a multiplier chain with the same ion trap, leading to a significant improvement of their rest frequency values