Multiple pieces of evidence point towards the presence of pre-existing DNA structure in the absence of ions. The first evidence comes from the observation of the frequency difference between the row and corresponding column of peaks arising from the coupling of a guanine carbonyl stretch mode with various other vibrational modes (Figure ). In general, for EVV 2DIR spectroscopy, the rows and columns of cross-peaks relating to the same mode, have an approximate reflective symmetry about the overtone line (𝜔 𝛼 = 𝜔 𝛽 -𝜔 𝛼 ). However, this symmetry is frequently broken by a negative frequency shift along the 𝜔 𝛽 -𝜔 𝛼 axis. This is because a combination band is usually shifted to a frequency lower than the sum of the fundamental frequencies by the process of mode-coupling. In our experimental spectrum (Figure ), the row of cross-peaks with frequencies which depend on potassium ion concentration are assigned to the guanine carbonyl stretch with a frequency between 1694 -1707 cm -1 . This frequency is unusually higher than the corresponding column of peaks with frequencies that are also dependent on potassium ion concentration and appears between 1671-1688 cm -1 . Assuming that these are not combination bands that are shifted to a higher frequency than the sum of the constituent fundamentals, this indicates that the guanine carbonyl stretch mode giving rise to the row, which we refer to as GCO I, is not the same one which gives rise to the column, which we refer to as GCO II.