Fig. 2

a Dissociated melting bubbles along a double strand of λ-DNA (taken under UHV, df =− 2.0 Hz, A = 14.1 nm, f₀ = 259.0 Hz). b Closer look at one of the larger bubbles, including an area of supercoiled buildup. c Distribution of interval distances between the protrusion features along the bubbles, with a mean of 1.42 nm. d Distances and antiphasic patterning of features. The larger than average distance of 0.78 nm can be attributed to observations where complex coated ssDNA regions appear elongated [25]. e Overlay of a possible molecular model to match the observed topography [DNA model from [26] (1BNA)]