Scanning force microscope with high-frequency cantilever
OwnerFredy Ruben Zypman Niechonski, Steven Joseph Eppellinventors
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Abstract
An apparatus and a process for determining resonant frequencies for a cantilever used to measure tip-to-sample distances on a scanning force microscope. The process uses a non-linear equation and does not require knowledge of the shape of the cantilever to obtain the measured forces. As the tip-to-sample distance varies, the resonant frequency of the cantilever changes. Instead of measuring the positions of the tip and sample and the spring constant (k) of the cantilever, the present invention measures the resonant frequency at each data point. The shifts in frequencies contain the information necessary to reconstruct the force-distance curve.
Claims20
A process for measuring a slope (G) of a Force vs Distance curve at a given point of that curve, comprising:
- (a) positioning a cantilever at a distance (d) from a sample;
- (b) exciting the natural vibrational modes into the cantilever and;
- (c) using a non-Hookian equation, solving for a value of the slope (G) of the force vs distance curve from the measured frequencies of the natural modes.
A method of obtaining a Force vs Distance curve representative of a two-object interaction, comprising;
- (a) positioning a tip of a cantilever at a first distance from a sample;
- (b) exciting the natural vibrational modes of the cantilever;
- (c) determining the value of the first distance;
- (d) determining the oscillation of the cantilever at a location along the cantilever;
- (e) determining the corresponding frequencies from step (d);
- (f) determining the slope (G) of the Force vs. Distance curve from a non-Hookian equation;
- (g) moving the cantilever to a second distance from the sample;
- (h) repeating steps (b) through (f) to obtain a second value of G at the second distance;
- (i) obtaining the G vs d relationship;
- and
- (j) obtaining the value of the Force vs. Distance curve by integration of the G vs. d relationship.
An apparatus for measuring topography or forces of a sample, comprising:
- a surface to support a sample;
- a cantilever;
- means to change the position of the cantilever with respect to the surface;
- control means to position the cantilever with respect to the sample and to determine a position of the cantilever with respect to the sample;
- means to determine the natural vibrations of the cantilever;
- and control means to determine forces acting between the sample and the cantilever using a non-Hookian equation.
Dependencies are inferred from the claim text.