“…In most previous work, the low frequenc;', large amplitude motion involved torsional motion.s, 6 ,10l,1,1 4 .1s In our previous work on substituted ethanes, we suggested that intramolecular interactions that effect torsional modes, can enhance mode coupling between states involving those torsional modes. 5 ,6, 14 , 15 As noted above, one can view ring puckering in cyclobutane as an extremely hindered torsion, in which the barrier to internal rotation about any C-C bond is essentiai.,. respectively, the K structure is resolved and the weak intensities of these bands prevent us from identifying peak fractionation.…”