Imaging atomically sharp crack tips in mica by contact mode AFM under ambient conditions

¹ Department of Materials Physics and Chemistry, University of Science and Technology Beijing, 30 Xueyuan Rd., 100083 Beijing, P.R. China
² Department of Chemical Engineering, University of Newcastle, Callaghan, NSW 2308, Australia

Corresponding author: yang.gan@newcastle.edu.au

Received: 28 April 2004
Revised: 30 November 2004
Accepted: 27 January 2005
Published online: 14 April 2005

Abstract

Using an Atomic Force Microscope (AFM) operated in contact mode under ambient conditions, we have tried to resolve atomically sharp cracks perpendicular to the basal plane of muscovite mica. However, although tip radius of probes of less than 10 nm allowed a lateral resolution of 0.7 nm and the tip-sample adhesive force has been minimized, our experimental results demonstrate that the molecular structure of crack tips can't still be resolved. Even worse, sometimes the tip-sample friction can disrupt the region around the crack tip. This thus leads to the conclusion that one will fail to resolve atomically sharp cracks under ambient conditions by contact AFM. The inability is due to low lateral resolution of contact AFM and strong tip-sample interaction force under ambient conditions. New techniques of scanning samples in liquids and UHV non-contact AFM both of which have true atomic resolution are strongly recommended for future studies.