Retrofitting an atomic force microscope with photothermal excitation for a clean cantilever response in low Q environments.

Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada.
The Review of scientific instruments (Impact Factor: 1.52). 05/2012; 83(5):053703. DOI: 10.1063/1.4712286
Source: PubMed

ABSTRACT It is well known that the low-Q regime in dynamic atomic force microscopy is afflicted by instrumental artifacts (known as "the forest of peaks") caused by piezoacoustic excitation of the cantilever. In this article, we unveil additional issues associated with piezoacoustic excitation that become apparent and problematic at low Q values. We present the design of a photothermal excitation system that resolves these issues, and demonstrate its performance on force spectroscopy at the interface of gold and an ionic liquid with an overdamped cantilever (Q < 0.5). Finally, challenges in the interpretation of low-Q dynamic AFM measurements are discussed.

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