Notes. The upper energy levels, frequencies, and Einstein A coefficients of the molecules are taken from Schöier et al. (2005). To complete the table, we included line detections reported in previous studies. For the CN lines, we do not distinguish between the hyper-fine splitting caused by the nuclear spin of nitrogen (described by quantum number F) due to limited spectral resolution. For the CCH lines, because the frequencies of the fine and hyper-fine splitting within the same N + 1 → N are very close (considering the four brightest transitions for a given N_J, F, we have the brightest four lines that are within 0.06 GHz), we do not distinguish the hyper-fine lines. For the NO and CH, we only list the fine structure and Λ-doublet because the hyper-fine lines are too close to be separated. For the aforementioned molecules, we list the E_up/k_B and ν_{rest − frame} with the highest Einstein A coefficient as a representative (for the CH lines, we list 3/2,  1⁺ → 1/2,  0⁻ and 3/2,  2⁻ → 1/2,  1⁺). The data of C³⁴S, HCN-VIB (v₂ = 1f) and c-C₃H₂ are taken from CDMS (Endres et al. 2016). For the HCN and the N²H⁺ lines, we do not consider their hyper-fine structure lines considering the spectral resolution and the intrinsic linewidths of the galaxies.

References. L11 = Lis et al. (2011), R09 = Riechers et al. (2009), V11 = van der Werf et al. (2011), W07 = Weiß et al. (2007), Y16 = Yang et al. (2016), Y17a = Yang et al. (2017), Y17b = Yang (2017).