Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 12: Postersitzung (Struktur und Dynamik reiner Oberfl
ächen, Grenzfl
äche fest-flüssig, Nanostrukturen, Teilchen und Cluster, Halbleiteroberfl
ächen und Grenzfl
ächen, Zeitaufgelöste Spektroskopie, Rastersondentechniken, Methodisches)

O 12.45: Poster

Montag, 24. März 2003, 18:00–21:00, P1

Development of a differential AFM for stress-strain measurements — •Nicola Maghelli, Othmar Marti, and Sabine Hild — Dept. of Experimental Physics, Albert Einstein Allee, 11 D-89069 ULM

Commercially available AFM often offer the possibility to acquire force distance curves by monitoring the deflection of a microlever that is brought in contact with the sample surface and then retracted by mean of a piezoelectric actuator. The main source of error is the simultaneous use of the lever itself both as distance and as force sensor: this can result in undesired crosstalks between these two quantities; moreover, the system is subjected to the electrical instabilities of the piezoelectric actuator such as creep, hysteresis or drift.

A solution is to use two different levers built on the same AFM chip and to monitor their signal at the same time: one lever will remain always in contact with the sample surface, acting as the control sensor element of a closed-loop feedback system stabilizing the distance of the whole AFM chip from the mean sample surface (thus also the distance of the second lever from it) against external vibration or electro-mechanical instabilities, while the other is the force sensor. First measurements on soft samples will be shown.

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