A method of operating a scanning probe microscope, wherein a control loop is provided which is configured for controlling one or more feedback parameters of the scanning probe microscope. One or more system identification measurements are performed during operation of the control loop, wherein during the one or more system identification measurements an excitation signal with a plurality of frequency components is introduced in the control loop and a resulting response signal indicative of a cantilever displacement or a stage-sample distance between a sensor device and a sample is measured. A model response function is identified using said excitation signal and said resulting response signal, wherein one or more settings and/or input signals are adapted in the control loop based on the identified model response function. The scanning probe microscope is used for characterization of the sample using the adapted one or more settings and/or input signals.

A method of carrying out sub-resonant tapping in an atomic force microscope includes causing a probe that is disposed above a sample to be translated in a direction parallel to a horizontal plane defined by the sample and to oscillate in a vertical direction that is perpendicular to the horizontal plane about an equilibrium line that is separated from the horizontal plane by a vertical offset. As a result, the probe repeatedly taps a surface of the sample. Each tap begins with a first contact of the probe on the surface followed by a progressive increase in force exerted by the sample on the probe until a peak force is attained. The vertical offset is controlled by relying at least in part on a feature other than the peak force as a basis for controlling the vertical offset.

A method of carrying out sub-resonant tapping in an atomic force microscope includes causing a probe that is disposed above a sample to be translated in a direction parallel to a horizontal plane defined by the sample and to oscillate in a vertical direction that is perpendicular to the horizontal plane about an equilibrium line that is separated from the horizontal plane by a vertical offset. As a result, the probe repeatedly taps a surface of the sample. Each tap begins with a first contact of the probe on the surface followed by a progressive increase in force exerted by the sample on the probe until a peak force is attained. The vertical offset is controlled by relying at least in part on a feature other than the peak force as a basis for controlling the vertical offset.

An atomic force microscope includes a cantilever operating in amplitude modulation mode. A controller determines the amplitude of the cantilever oscillation by processing a signal representative of the cantilever motion by square-rooting a signal having a value substantially equal to a sum of a square of the received signal and a squared and phase-shifted version of the received signal. The aforementioned processing, in some implementations is implemented using analog circuit components.

An atomic force microscope includes a cantilever operating in amplitude modulation mode. A controller determines the amplitude of the cantilever oscillation by processing a signal representative of the cantilever motion by square-rooting a signal having a value substantially equal to a sum of a square of the received signal and a squared and phase-shifted version of the received signal. The aforementioned processing, in some implementations is implemented using analog circuit components.

An improved mode of AFM imaging (Peak Force Tapping (PFT) Mode) uses force as the feedback variable to reduce tip-sample interaction forces while maintaining scan speeds achievable by all existing AFM operating modes. Sample imaging and mechanical property mapping are achieved with improved resolution and high sample throughput, with the mode workable across varying environments, including gaseous, fluidic and vacuum.

An improved mode of AFM imaging (Peak Force Tapping (PFT) Mode) uses force as the feedback variable to reduce tip-sample interaction forces while maintaining scan speeds achievable by all existing AFM operating modes. Sample imaging and mechanical property mapping are achieved with improved resolution and high sample throughput, with the mode workable across varying environments, including gaseous, fluidic and vacuum.

Methods and apparatus for obtaining extremely high sensitivity chemical composition maps with spatial resolution down to a few nanometers. In some embodiments these chemical composition maps are created using a combination of three techniques: (1) Illuminating the sample with IR radiation than is tuned to an absorption band in the sample; and (2) Optimizing a mechanical coupling efficiency that is tuned to a specific target material; (3) Optimizing a resonant detection that is tuned to a specific target material. With the combination of these steps it is possible to obtain (1) Chemical composition maps based on unique IR absorption; (2) spatial resolution that is enhanced by extremely short-range tip-sample interactions; and (3) resonant amplification tuned to a specific target material. In other embodiments it is possible to take advantage of any two of these steps and still achieve a substantial improvement in spatial resolution and/or sensitivity.

Methods and apparatus for obtaining extremely high sensitivity chemical composition maps with spatial resolution down to a few nanometers. In some embodiments these chemical composition maps are created using a combination of three techniques: (1) Illuminating the sample with IR radiation than is tuned to an absorption band in the sample; and (2) Optimizing a mechanical coupling efficiency that is tuned to a specific target material; (3) Optimizing a resonant detection that is tuned to a specific target material. With the combination of these steps it is possible to obtain (1) Chemical composition maps based on unique IR absorption; (2) spatial resolution that is enhanced by extremely short-range tip-sample interactions; and (3) resonant amplification tuned to a specific target material. In other embodiments it is possible to take advantage of any two of these steps and still achieve a substantial improvement in spatial resolution and/or sensitivity.

A sharpening method for a probe tip of an Atomic Force Microscope (AFM) includes the steps of dripping a prepared slurry on a glass slide to form a droplet on the glass slide, where particles of the prepared slurry are diamond powder; infiltrating the tip to be sharpened with the prepared slurry; setting operation mode of the AFM to tapping in the fluid and lowering the probe into droplet till the probe cantilever beam is immersed completely in the droplet; setting vibration parameters, scanning parameters, and sharpening time, performing tip sharpening; and evaluating the sharpening results, and finishing sharpening. When the AFM works in a tapping mode in fluid, the tip of the self-excited oscillating probe is sharpened under the grinding effect of the diamond particles. The method is simple and effective, and easy to implement.