Pairs of a- and b-type transitions of syn-glycolamide with K_a = 4, 5 at J″ = 37 (left panel) that coalesce into a quadruply degenerate line at J″ = 41 (right panel) during the mmW experiment while going up in frequency (b-type transitions colored in green and a-type transitions in red, respectively). The broadening is higher than that of conventional room-temperature experiments due to the effect of the temperature of the cell. The x axis is labeled in MHz.