AM/FM MEASUREMENTS USING MULTIPLE FREQUENCY ATOMIC FORCE MICROSCOPY
First Claim
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1. An atomic force microscope system, comprising:
- a cantilever having a tip at one end and a driving part at its other end;
a cantilever position detector which detects a position of the cantilever;
a positioning system for controlling a position of the cantilever relative to a sample, the positioning system having a controller receiving feedback from the position detector, and producing outputs that drive movement of the cantilever,the positioning system driving the cantilever at or near two or more eigenmodes of the cantilever,where the positioning system operating by;
first operating by exciting the probe tip at a first eigenmode frequency and a first amplitude, and using the feedback to controls the distance between the base of the cantilever and the sample surface to maintain said distance,exciting a second eigenmode frequency of the cantilever at a second amplitude different than the first amplitude, where at the second amplitude the cantilever eigenmode is interacting with predominantly repulsive forces to the surface,determining amplitude and phase of the first eigenmode and of the second eigenmode, and using said amplitude and phase of the first eigenmode and of the second eigenmode to characterize the surface.
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Abstract
Apparatus and techniques presented combine the features and benefits of amplitude modulated (AM) atomic force microscopy (AFM), sometimes called AC mode AFM, with frequency modulated (FM) AFM. In AM-FM imaging, the topographic feedback from the first resonant drive frequency operates in AM mode while the phase feedback from second resonant drive frequency operates in FM mode. In particular the first or second frequency may be used to measure the loss tangent, a dimensionless parameter which measures the ratio of energy dissipated to energy stored in a cycle of deformation.
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Citations
14 Claims
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1. An atomic force microscope system, comprising:
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a cantilever having a tip at one end and a driving part at its other end; a cantilever position detector which detects a position of the cantilever; a positioning system for controlling a position of the cantilever relative to a sample, the positioning system having a controller receiving feedback from the position detector, and producing outputs that drive movement of the cantilever, the positioning system driving the cantilever at or near two or more eigenmodes of the cantilever, where the positioning system operating by;
first operating by exciting the probe tip at a first eigenmode frequency and a first amplitude, and using the feedback to controls the distance between the base of the cantilever and the sample surface to maintain said distance,exciting a second eigenmode frequency of the cantilever at a second amplitude different than the first amplitude, where at the second amplitude the cantilever eigenmode is interacting with predominantly repulsive forces to the surface, determining amplitude and phase of the first eigenmode and of the second eigenmode, and using said amplitude and phase of the first eigenmode and of the second eigenmode to characterize the surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of operating an atomic force microscope system, comprising:
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driving a cantilever to different movement positions, the cantilever having a tip at one end and a driving part at its other end; detecting a position of the cantilever; controlling said driving for controlling a position of the cantilever relative to a sample, receiving feedback from the position detector, and producing outputs that drive movement of the cantilever, said driving the cantilever comprising driving the cantilever at or near two or more eigenmodes of the cantilever, first exciting the probe tip at a first eigenmode frequency and a first amplitude, and using the feedback to controls the distance between the base of the cantilever and the sample surface to maintain said distance, second exciting a second eigenmode frequency of the cantilever at a second amplitude different than the first amplitude, where at the second amplitude the cantilever eigenmode is interacting with predominantly repulsive forces to the surface, and determining amplitude and phase of the first eigenmode and of the second eigenmode, and using said amplitude and phase of the first eigenmode and of the second eigenmode to characterize the surface. - View Dependent Claims (11, 12, 13, 14)
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Specification