Experimental determination of conservative and dissipative parts in the tapping mode on a grafted layer: comparison with frequency modulation data
Abstract
The aim of the present work is to extract the conservative and dissipative parts of the tip-sample interaction from the atomic force microscope amplitude modulation mode (AM, often called tapping). To do so, analytical expressions are used to transform the experimental amplitudes and phase variations with tip-sample distance to frequency shift and damping coefficient. The experimental procedure for the separation is detailed. The separated conservative and dissipative parts from the AM mode are compared for two driving frequencies, and then they are compared to the frequency modulation mode (FM, often called resonant non-contact) measurements for two different amplitudes. The conservative parts from the AM measurements are similar to the frequency shifts measured in the FM mode and also the dissipative parts from the AM measurements are very close to the dissipation measured in the FM mode. Experimentally, this good agreement is related to the small amplitude variation in the AM data on a chemically controlled grafted layer.
Those results show experimentally that the AM and FM modes are just two different ways to probe the same tip-sample interaction. They also validate the AM data treatment to separate the conservative and dissipative parts as the only hypothesis needed is that only the fundamental harmonic contributes to the signal.- Publication:
-
Nanotechnology
- Pub Date:
- June 2005
- DOI:
- 10.1088/0957-4484/16/6/046
- Bibcode:
- 2005Nanot..16..901M