The next largest cluster explored was the (2, 2, 0) cluster. Figure shows the experimental and calculated structures of the (2, 2, 0) cluster. In the experimental spectrum we see the presence of a free OH stretch and both free symmetric and asymmetric NH 2 stretches, suggesting at least one iodic acid molecule remains protonated. Again the fingerprint region is dominated by the NH 2 bending/wagging modes with the iodine related stretches showing up below 1000 cm -1 .