An atomic force microscope and method for detecting photo-induced force using the atomic force microscope utilizes light from a photonic source at a tip-sample interface that results in photo-induced force gradient, which is detected by measuring a resonant frequency of a vibrational mode of a cantilever of the atomic force microscope.

A method for obtaining optical spectroscopic information about a sub-micron region of a sample with quantitatively controlled depth/volume of the sample subsurface using a scanning probe microscope. With controlled probing depth/volume, the method can separate top surface data from subsurface optical/chemical information. The method can also be applied in liquid suitable for studying biological and chemical samples in their native aqueous environments, as opposed to air. In the method, a depth-controlled spectrum of the surface layer is constructed by illuminating the sample with a beam of infrared radiation and measuring a probe response using at least one of the resonant frequencies of the probe. The surface sensitivity is obtained by limiting the heat diffusion effect of the subsurface so as to confine the signal. The signal confinement is achieved through non-linearity of the acoustic wave with probe, as well as benefits gained by a high modulation frequency of the infrared radiation source at >1 MHz.

A method for obtaining optical spectroscopic information about a sub-micron region of a sample with quantitatively controlled depth/volume of the sample subsurface using a scanning probe microscope. With controlled probing depth/volume, the method can separate top surface data from subsurface optical/chemical information. The method can also be applied in liquid suitable for studying biological and chemical samples in their native aqueous environments, as opposed to air. In the method, a depth-controlled spectrum of the surface layer is constructed by illuminating the sample with a beam of infrared radiation and measuring a probe response using at least one of the resonant frequencies of the probe. The surface sensitivity is obtained by limiting the heat diffusion effect of the subsurface so as to confine the signal. The signal confinement is achieved through non-linearity of the acoustic wave with probe, as well as benefits gained by a high modulation frequency of the infrared radiation source at >1 MHz.

Method and system for performing characterization of a sample using an atomic force microscopy system. An actuation signal is provided to a photo-thermal actuator which is configured to excite the probe by means of an optical excitation beam incident on the cantilever. The probe is configured to be bendable by means of the optical excitation beam impinging on it. The actuation signal is configured to include at least one modulation frequency. The probe tip motion is monitored for determining at least a subsurface characterization data.

Mid-infrared photothermal heterodyne imaging (MIR-PHI) techniques described herein overcome the diffraction limit of traditional MIR imaging and uses visible photodiodes as detectors. MIR-PHI experiments are shown that achieve high sensitivity, sub-diffraction limit spatial resolution, and high acquisition speed. Sensitive, affordable, and widely applicable, photothermal imaging techniques described herein can serve as a useful imaging tool for biological systems and other submicron-scale applications.

Mid-infrared photothermal heterodyne imaging (MIR-PHI) techniques described herein overcome the diffraction limit of traditional MIR imaging and uses visible photodiodes as detectors. MIR-PHI experiments are shown that achieve high sensitivity, sub-diffraction limit spatial resolution, and high acquisition speed. Sensitive, affordable, and widely applicable, photothermal imaging techniques described herein can serve as a useful imaging tool for biological systems and other submicron-scale applications.

An apparatus and method of performing sample characterization with an AFM and a pulsed IR laser directed at the tip of a probe of the AFM. The laser pulses are synchronized with the oscillatory drive of the AFM and may only interact with the tip/sample on selected cycles of the oscillation. Peak force tapping mode is preferred for AFM operation. Nano-mechanical and nano-spectroscopic measurements can be made with sub-50 nm, and even sub-20 nm, resolution.

An apparatus and method of performing sample characterization with an AFM and a pulsed IR laser directed at the tip of a probe of the AFM. The laser pulses are synchronized with the oscillatory drive of the AFM and may only interact with the tip/sample on selected cycles of the oscillation. Peak force tapping mode is preferred for AFM operation. Nano-mechanical and nano-spectroscopic measurements can be made with sub-50 nm, and even sub-20 nm, resolution.

A method of operating an atomic force microscope, comprising a probe, the probe being moved forth and back during respective trace and retrace times of a scan line, the method comprising: a) during trace time, oscillating the probe, b) generating a z feedback signal to keep an amplitude of oscillation of the probe constant at a setpoint value, the z feedback signal being generated by a first feedback loop, c) during retrace time, placing the probe in a drift compensation state by changing the setpoint value to a different value so that the z feedback signal being generated by the first feedback loop causes the probe to move away from the sample and oscillate free, d) detecting an amplitude of free oscillation of the probe and adjusting with a second feedback loop its excitation signal to maintain the amplitude of free oscillation of the probe close to a set value.

A method of operating an atomic force microscope, comprising a probe, the probe being moved forth and back during respective trace and retrace times of a scan line, the method comprising: a) during trace time, oscillating the probe, b) generating a z feedback signal to keep an amplitude of oscillation of the probe constant at a setpoint value, the z feedback signal being generated by a first feedback loop, c) during retrace time, placing the probe in a drift compensation state by changing the setpoint value to a different value so that the z feedback signal being generated by the first feedback loop causes the probe to move away from the sample and oscillate free, d) detecting an amplitude of free oscillation of the probe and adjusting with a second feedback loop its excitation signal to maintain the amplitude of free oscillation of the probe close to a set value.