Rotational transitions of CH₂D⁺determined by high-resolution IR spectroscopy

Abstract

<i>Context. <i/>Deuterated forms of CH are responsible for deuterium fractionation in warmer environments. Current searches for CH<sub>2<sub/>D<sup>+<sup/> are hampered by a lack of accurate laboratory data.<i>Aims. <i/>We demonstrate that IR spectroscopy at very high resolution can make accurate rotational predictions.<i>Methods. <i/>By combining a low-temperature ion trap with a narrow-bandwidth IR light source, we are able to measure vibrational transitions with high accuracy. A subsequent fit using an asymmetric rotor model allows predictions of MHz accuracy or even better.<i>Results. <i/>We predict rotational transitions up to 1.5 THz.