Detection of six isotopologues of CH

We present the detection of the five 13C isotopologues and the acetylenic deuterated species of CH3C4H towards TMC-1 using observations from the QUIJOTE line survey taken with the Yebes 40m telescope. The identification of the CH3C13CCCH and CH3CCCCD species was based on previous laboratory spectroscopic data. In contrast, for the remaining 13C species, 13CH3CCCCH, CH313CCCCH, CH3CC13CCH, and CH3CCC13CH, we carried out the spectroscopic identification directly in the QUIJOTE data. In this manner, the molecular constants derived in this work constitute the first spectroscopy information of these four species. We find that 12C/13C is 93 ± 11 for the five possible substitutions, and that the H/D abundance ratio is 54.2 ± 7.8. As previously reported, the TMC-1 gas-phase chemical model with multiply deuterated molecules accounts for the CH3C4H/CH3C4D abundance ratio calculated in this work.