Regensburg 2016 – scientific programme
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DS: Fachverband Dünne Schichten
DS 16: Layer Properties: Electrical, Optical, and Mechanical
DS 16.11: Talk
Tuesday, March 8, 2016, 12:15–12:30, H11
Vibrational modes of ultrathin carbon nanomembrane mechanical resonators — •Xianghui Zhang1, Reimar Waitz2, Fan Yang2, Carolin Lutz2, Polina Angelova1, Armin Gölzhäuser1, and Elke Scheer2 — 1Fakultät für Physik, Universität Bielefeld, 33615 Bielefeld, Germany — 2Fachbereich für Physik, Universität Konstanz, 78457 Konstanz, Germany
We report measurements of vibrational mode shapes of mechanical resonators made from ultrathin carbon nanomembranes (CNMs) with a thickness of approximately 1 nm. CNMs are prepared from electron irradiation induced cross-linking of aromatic self-assembled monolayers (SAMs) and the variation of membrane thickness and/or density can be achieved by varying the precursor molecule. The vibration of the membrane was actuated by applying a sinusoidal voltage to a piezoelectric disk on which the sample was glued. The vibrational mode shapes were visualized with an imaging Mirau interferometer using a stroboscopic light source. Several degenerate normal modes of a square membrane can be readily identified and their dynamic behavior can be well described by linear response theory of a membrane with negligible bending rigidity. Applying Fourier transformations to the time-dependent surface profiles, the dispersion relation of the transverse membrane waves can be obtained and its linear behavior confirms the membrane model. Comparing the dispersion relation to an analytical model, the static stress of the membranes was determined and found to be caused by the fabrication process.