USE OF ATOMIC-FORCE MICROSCOPY TO IMAGE SURFACES DURING FLUID-FLOW

Use of atomic force microscopy (AFM) to image surfaces held under elec trochemical control in the presence of fluid flow has been demonstrate d. The performance of AFM during fluid flow was evaluated on (i) the a tomic level (10 to 200 nm) using cleaved mica as the substrate, (ii) o n the micron scale (1 to 12 mum) using a gold calibration ruling as th e substrate, and (iii) on the micron scale during in situ electrodepos ition of Cu onto Pt(100). The Reynolds numbers associated with the flu id flow were evaluated by using the diameter and height of the cell as cross-sectional area, and the hydraulic diameter based on the same ar ea as characteristic length. Maximum Reynolds numbers of 8 for atomic imaging (1 to 25 nm) and 130 for larger scales (1 to 12 mum) may be ma intained without loss of imaging quality. The engagement force was the significant parameter which influenced whether images could be obtain ed during flow. The critical engagement force required for imaging var ied linearly with flow rate.