Nanometer scale springs

We used a set of silicon and silicon nitride V-shaped cantilevers with nominal spring constants, kn, from 0.06 to 47 N/m, stiffer cantilevers were applied to harder materials. Actual values of spring constants were determined the fundamental resonant frequency calibration proposed earlier and cross-checked by both cantilever-against-cantilever technique and added mass technique (see review of different approaches in Ref. 6). Tip radii were measured using mixed gold nanoparticles. Measured radii were in the range of 20 - 60 nm. Shape of the tip ends at a nanometer scale was virtually symmetrical and for most tips, spherical approximation could be used. 

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