Vibrational satellite pattern of the syn conformer in the millimeter wave spectrum of acrylamide. The upper panel shows a pair of degenerate 46 _1, 46 ← 45 _0, 45 and 46 _0, 46 ← 45 _1, 45 transitions for the ground state (G.S.) and the excited vibrational states (yellow diamonds). The green circle symbols represent the ground state lines included in the fit. The lower panel illustrates a stick reproduction of the ground state and v₂₄ = 1, 2 spectra using the spectroscopic constants from Table 1.