Laboratory microwave spectroscopy of the doubly deuterated cyanomethyl radical, D2CCN

11 pags., 2 figs., 2 tabs.The microwave spectrum of the doubly deuterated cyanomethyl radical (DCCN) in its ground electronic state (B) has been observed for the lowest four rotational transitions (N = 1–0, 2–1, 2–1 and 2–1) using a Fourier transform microwave spectrometer in combination with a pulsed discharge nozzle. A total of 394 hyperfine components were measured and subjected to a least squares analysis which allowed determining twelve hyperfine constants for nitrogen and deuterium nuclei. With this new set of molecular constants we obtained accurate predictions for low N rotational transitions with hyperfine structure, and searched for this species in TMC–1.C. C. and J. C. thank to the European Research Council for fund-ing support under Synergy Grant ERC-2013-SyG, G.A. 610256 (NANOCOSMOS) and to Ministerio de Ciencia e Innovación for funding support through projects AYA2016–75066–C2–1–P andPID2019–107115GB–C21. Y. E. thanks Ministry of Science and Technology of Taiwan for funding support under grant MOST108–2113–M–009–25