Submillimeter Laboratory Identification of CH+ and CH2D+

Laboratory identification of two basic and important interstellar molecular ions is presented. The J = 1 0 rotational transition of (CH+)-C-12 together with those of (CH+)-C-13 and (CD+)-C-12 was observed in the laboratory. The newly obtained frequencies were found to be different from those reported previously. Various experimental evidences firmly support the new measurements. In addition, the Zeeman effect and the spin-rotation hyperfine interaction enforce the laboratory identification with no ambiguity. Rotational lines of CH2D+ were observed in the submillimeter-wave region. This laboratory observation is consistent with a recent tentative identification of CH2D+ toward On IRc2.