Determination of the resolution in scanning near-field optical images with the help of shear force feedback

Author(s):  
Dominique Barchiesi ◽  
Christian Pieralli
1995 ◽  
Vol 34 (19) ◽  
pp. 3793 ◽  
Author(s):  
Sergey I. Bozhevolnyi ◽  
Igor I. Smolyaninov ◽  
Ole Keller

Author(s):  
Patrick J. Moyer

Near-field scanning optical microscopy (NSOM) has been used to characterize and modify surfaces with lateral spatial resolution as high as 50 nm. Some of these experiments were performed under electrochemical conditions. Progress towards this goal involved several important steps. They include proving adequate operation of the shear force feedback mechanism in liquids and fabrication of appropriate NSOM fiber probes.With regards to shear force feedback, which is used to maintain the fiber probe within the near field of the sample, there has been ample discussion regarding the physics of the tip-sample interaction. It is important for biological and photoelectrochemical applications that the feedback mechanism operates successfully in liquid environments. Our results indicate that shear force operation in water allows for high spatial resolution NSOM characterization while providing high force sensitivity. When comparing the frequency spectra of the probe resonances in air and water, the water resonance is broadened. The broadened resonance peak when completely immersing the probe in water indicates an increase in damping.


2015 ◽  
Vol 180 ◽  
pp. 331-345 ◽  
Author(s):  
Philippe Dauphin-Ducharme ◽  
W. Jeffrey Binns ◽  
Michael E. Snowden ◽  
David W. Shoesmith ◽  
Janine Mauzeroll

The successful development of scanning probe techniques to characterize corrosion in situ using multifunctional probes is intrinsically tied to surface topography signal decoupling from the measured electrochemical fluxes. One viable strategy is the shear force controlled scanning microcapillary method. Using this method, pulled quartz micropipettes with an aperture of 500 nm diameter were used to resolve small and large variations in topography in order to quantify the local corrosion rate of microgalvanically and galvanically corroded Mg alloys. To achieve topography monitoring of corroded surfaces, shear force feedback was employed to position the micropipette at a reproducible working height above the substrate. We present proof of concept measurements over a galvanic couple of a magnesium alloy (AE44) and mild steel along with a microgalvanically corroded ZEK100 Mg alloy, which illustrates the ability of shear force to track small (1.4 μm) and large (700 μm) topographic variations from high aspect ratio features. Furthermore, we demonstrate the robustness of the technique by acquiring topographic data for 4 mm along the magnesium–steel galvanic couple sample and a 250 × 30 μm topography map over the ZEK100 Mg alloy. All topography results were benchmarked using standard optical microscopies (profilometry and confocal laser scanning microscopy).


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