High-resolution vibrational and rotational spectroscopy of CD2H+ in a cryogenic ion trap

Abstract The low-lying rotational states ( J  = 0, … , 5) of CD 2 H + have been probed by high-resolution ro-vibrational and pure rotational spectroscopy, applying several action spectroscopic methods in a cryogenic 22-pole ion trap. For this, the ν 1 ro-vibrational band has been revisited, detecting 108 transitions, among which 36 are new. The use of a frequency comb system allowed us to measure the ro-vibrational transitions with high precision and accuracy, typically better than 1 MHz. The high precision has been confirmed by comparing equal combination differences in the ground and excited state. Moreover, precise predictions of pure rotational transitions were possible for the ground state. Twenty-five rotational transitions have been detected directly by a novel IR-mm-wave double resonance method, giving rise to highly accurate ground state spectroscopic parameters.