Detection of the propargyl radical at <i>λ</i> 3 mm,

We report the detection of propargyl radical (CH 2 CCH) in cold dark cloud TMC-1 λ 3 mm wavelength band. recently discovered this species space toward same source at a 8 mm. In those observations, various hyperfine components 0,2 –1 0,1 rotational transition, 37.5 GHz, were detected using Yebes 40 m telescope. Here, we used IRAM 30 telescope to detect ten 5 0,5 –4 0,4 lying 93.6 GHz. The observed frequencies differ by 0.2 MHz with respect predictions from available laboratory data. This difference is significant for radio-astronomical search CH CCH interstellar sources narrow lines. thus included measured new spectroscopic analysis provide accurate frequency millimeter wavelengths. Moreover, recommend that future searches clouds be carried out rather than transition about five times more intense one TMC-1, which implies detecting former requires seven less time latter. constrain temperature 9.9 ± 1.5 K, indicates levels are thermalized gas kinetic temperature. revised value column density (including ortho and para species) (1.0 0.2) × 10 14 cm −2 , CCH/CH abundance ratio slightly higher, approaching one. study opens door detections other clouds, making it possible further investigate role very abundant hydrocarbon synthesis large organic molecules, such as aromatic rings.