Laboratory rotational ground state transitions of NH3D+and CF+ Article Swipe
YOU?
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· 2016
· Open Access
·
· DOI: https://doi.org/10.1051/0004-6361/201629101
· OA: W2481286819
Aims. This paper reports accurate laboratory frequencies of the rotational\nground state transitions of two astronomically relevant molecular ions, NH3D+\nand CF+. Methods. Spectra in the millimeter-wave band were recorded by the\nmethod of rotational state-selective attachment of He-atoms to the molecular\nions stored and cooled in a cryogenic ion trap held at 4 K. The lowest\nrotational transition in the A state (ortho state) of NH$_3$D$^+$ ($J_K = 1_0 -\n0_0$), and the two hyperfine components of the ground state transition of\nCF$^+$($J = 1 - 0$) were measured with a relative precision better than\n$10^{-7}$. Results. For both target ions the experimental transition\nfrequencies agree with recent observations of the same lines in different\nastronomical environments. In the case of NH$_3$D$^+$ the high-accuracy\nlaboratory measurements lend support to its tentative identification in the\ninterstellar medium. For CF$^+$ the experimentally determined hyperfine\nsplitting confirms previous quantum-chemical calculations and the intrinsic\nspectroscopic nature of a double-peaked line profile observed in the $J = 1 -\n0$ transition towards the Horsehead PDR.\n
