Ultramicroscopy 97 (2003) 315–320 Lateral force microscopy profiles for amorphous potentials A.M.F. Rivas, R.R.M. Zamora, R. Prioli* Departamento de F! ısica, Pontif ! ıcia Universidade Cat ! olica do Rio de Janeiro, Cx. Postal 38071, 22452-970, Rio de Janeiro, RJ, Brazil Received 10 July 2002; received in revised form 14 January 2003 Abstract In this work, the lateral force profiles of the scanning force microscope tip on an amorphous surface were simulated with the use of an independent oscillator model. The correlation between the lateral force profiles and the surface potential were studied as a function of the tip-surface normal force and relative scanning velocity. It is shown that the microscope resolution is governed by the quotient between the average potential interaction energy and the average elastic energy stored before the jumps. We show that there is an optimal velocity with which the scanning tip better senses the surface potential and we present its scaling laws. r 2003 Elsevier Science B.V. All rights reserved. PACS: 07.79.Sp; 61.16.C; 62.20.Qp Keywords: Atomic force microscopy; Friction; Tribology; Amorphous surface 1. Introduction The understanding of physical phenomena, occurring in nanoscale, such as friction has become very important due to the fact that many technological devices like hard disks and micro- lectro mechanical systems are having their dimen- sions reduced by the industry. While operating, such nanoscale devices experience very low inter- action forces which include the intermolecular interaction between the component parts, adhe- sion forces, and viscous drag forces. It is known that, in such operating conditions, the macro- scopic laws of friction [1] are no longer valid. In nanoscale, friction is proportional to the true area of contact, which is not linearly proportional to the normal force [2], and it is velocity dependent [3]. The dependence of friction with the scanning velocity may be explained with a combination of three different models. At very low scanning velocities ðv-0Þ; the energy dissipation is shown to be mainly caused by the nonlinear dynamics of the moving parts [4–6]. At higher velocities, friction is shown to present a logarithmic dependence with velocity. This logarithmic dependence may be explained by a combination of a thermally activated stick-slip behavior [3,7] and the kinetics of nuclea- tion of water bridges between the moving parts [8]. In this work, we call our attention to the first regime, in which the movement of a scanning tip is controlled by the nonlinear dynamics of the sliding system. *Corresponding address. Departamento de F! ısica, Pontif ! ıcia Universidade Cat ! olica do Rio de Janeiro, Rua Marqu# es de S * ao Vicente, 225 - G! avea, Caixa Postal 38071, 22453-970, Rio de Janeiro, RJ, Brazil. Tel.: +55-21-3114-1272; fax: +55-21-3114- 1275. E-mail address: prioli@vdg.fis.puc-rio.br (R. Prioli). 0304-3991/03/$ - see front matter r 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0304-3991(03)00057-3