Comment on ‘‘Superstructures of Pb monolayers electrochemically deposited on Ag(111)’’

Using scanning tunneling microscopy, a long-wavelength pattern was observed by M\"uller et al. [Phys. Rev. B 46, 12 899 (1992)] in Pb monolayers on Ag(111) formed by underpotential electrochemical deposition. We point out that the monolayer is incommensurate and so it should be described as having substrate-induced spatial modulations, and we also demonstrate that one can accurately calculate the long-wavelength spacing and rotation angle, which are shown to depend on electrode potential.