DM-DR measurements of Aa n-propanol of the transition around 232.55 GHz. The lower panels show two DM-DR measurements where the A and E components of the transition are used as pump frequencies at 113 811.6420 MHz and 113 810.5391 MHz, respectively. A conventional measurement is shown in the upper panel. E* transitions, which are forbidden in rigid rotors (Herschbach & Swalen 1958), secure the assignment of internal rotation components. We note that slightly off-resonant pumping leads to small, asymmetric features of A and E components in the DM-DR spectrum of the other one, as pumped A and E components are rather close in frequency, cf. Zingsheim et al. (2021).