Fig. 3
λ-DNA subjected to UHV conditions on different substrates. a Untreated DNA on Au(111) (df =− 6.2 Hz, A = 12.6 nm, f0 = 286.3 Hz). b [(HtomMe)Cu2]3+-treated DNA on Au(111) (df =− 2.0 Hz, A = 14.1 nm, f0 = 259.0 Hz). The residues on the otherwise flat atomic planes are likely due to residual complex molecules. c DNA on potassium bromide (df =− 8.6 Hz, A = 4.7 nm, f0 = 302.0 Hz, inset: df =− 20.2 Hz, A = 1.9 nm, f0 = 302.0 Hz). d Distribution of groove distances, along with corresponding mean values for different substrates (Au, KBr)