From images to interactions: high-resolution phase imaging in tapping-mode atomic force microscopy.
In tapping-mode atomic force microscopy, the phase shift between excitation and response of the cantilever is used as a material-dependent signal complementary to topography. The localization of information in the phase signal is demonstrated with 1.4-nm lateral resolution on purple membrane of Halobacterium salinarum in buffer solution. In a first-order approximation, the phase signal is found to correlate with modulations of the tip oscillation amplitude, induced by topography. Extending the analysis to contributions of the tip-sample interaction area as a second-order approximation, a method is proposed to extract information about the interaction from the phase signal for surfaces with a roughness in the order of the tip radius.
Stark
M
M
Max Planck Institute for Biochemistry, Department of Molecular Structural Biology, D-82152 Martinsried, Germany. stark@biochem.mpg.de
Möller
C
C
Müller
D J
DJ
Guckenberger
R
R
D002021:Buffers; D019617:Halobacterium salinarum / Q000166:cytology / Q000648:ultrastructure*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D018625:Microscopy, Atomic Force / Q000379:methods*; D018717:Purple Membrane / Q000648:ultrastructure*; D012680:Sensitivity and Specificity; D012996:Solutions; D013816:Thermodynamics
D002021:Buffers; D012996:Solutions