Properly interpreting scanning tunneling microscopy images: the Cu(1 0 0)-c(2×2)N surface revisited

Recent scanning tunneling microscopy (STM) and photoelectron diffraction studies of the Cu(1 0 0)-c(2×2)N system have led to the proposal of a “new type of adsorbate-induced surface reconstruction” involving the movement of Cu atoms perpendicular to the surface. Claims were made that images from prior STM studies were misinterpreted. We present STM images that clearly contradict these claims. We discuss the role of tip structure in the imaging process and demonstrate how tips with asymmetric apexes can result in STM images that can easily be misinterpreted.