Deformation observed on soft surfaces studied with an AFM

Albrecht L. Weisenhorn; Sandor Kasas; J. M. Solletti; Mitra Khorsandi; V. Gotzos; D. U. Roemer; G. P. Lorenzi

doi:10.1117/12.146382

4 June 1993 Deformation observed on soft surfaces studied with an AFM

Albrecht L. Weisenhorn, Sandor Kasas, J. M. Solletti, Mitra Khorsandi, V. Gotzos, D. U. Roemer, G. P. Lorenzi

Proceedings Volume 1855, Scanning Probe Microscopies II; (1993) https://doi.org/10.1117/12.146382
Event: OE/LASE'93: Optics, Electro-Optics, and Laser Applications in Scienceand Engineering, 1993, Los Angeles, CA, United States

Abstract

The Atomic Force Microscope (AFM) can easily image 'hard' sample surfaces with atomic or molecular resolution. For 'soft' samples, such as organic macromolecules or biological objects, this resolution power is very difficult to reach, because the AFM tip causes large deformation. This deformation makes the sample surface to appear thinner in the AFM image. We have observed this effect on a Langmuir-Blodgett (LB) film of pentadecavaline which has been imaged in water as well as in air. The high capillary forces when imaging in air cause the film to appear half as thick as expected. In water, where the capillary forces are eliminated, the height of the LB film in the AFM image is correct. On actin fibers even a small change in the applied force has a big effect on the height of the AFM image: Changing the force from 0.9 nN to 1.8 nN decreases the apparent height from 5.7 nm to 3.6 nm. Increasing the force to 18 nN, brings the height down to 2.1 nm.

Citation Download Citation

Albrecht L. Weisenhorn, Sandor Kasas, J. M. Solletti, Mitra Khorsandi, V. Gotzos, D. U. Roemer, and G. P. Lorenzi "Deformation observed on soft surfaces studied with an AFM", Proc. SPIE 1855, Scanning Probe Microscopies II, (4 June 1993); https://doi.org/10.1117/12.146382

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