Tip-sample interactions in dynamic force microscopy of polyvinyl alcohol films

✍ Scribed by Haugstad, Greg; Gladfelter, Wayne L; Jones, Richard R

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 261 KB
• Volume: 49
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(200005)49:5<427::aid-pi238>3.0.co;2-7

✦ Synopsis

Dynamic force microscopy (DFM) was performed in air on ultrathin polyvinyl alcohol (PVA) ®lms. Nominal non-contact and intermittent solid contact regimes are identi®ed in measurements of amplitude and phase as a function of the mean distance from the sample. Evidence suggests that the nominal non-contact regime is divided into two subregimes: true non-contact, in which only longrange attractive forces exist, and intermittent ¯uid contact, involving brief penetration of the tip into a ¯uidized zone at the tip±polymer interface. Viscous ¯uid damping differs among three mesoscopic ®lm components, producing variable `resistance' to intermittent solid contact. As a result, some components of the ®lm are imaged in intermittent ¯uid contact and others in intermittent solid contact, within a single image. Approach±withdrawal amplitude hysteresis correlates with amplitude damping, and is consistent with component-speci®c surface ¯uidity (meniscus formation). Differences in surface ¯uidity are interpreted in terms of relative crystallinity.