Atomic force microscopy apparatus, methods, and applications

A system for measuring the time-evolution of charge or polarization induced by light in a sample, comprising:

• an atomic force microscope (AFM) having:
• a control circuitry,
• a cantilever with a tip located at a known height above the sample;
• a drive mechanism operatively coupling the cantilever and the control circuitry;
• a laser configured to emit light at the tip of the cantilever;
• and
• a photodetector coupled to the control circuitry;
• a pulse generator coupled to a light source configured to illuminate the sample;
• and
• a timing component configured to trigger the pulse generator.

A method for measuring the time-evolution of charge or polarization induced by light in a sample, comprising the steps of:

• providing an AFM in operating condition including a light source for illumination of a sample and a voltage source;
• obtaining a reference measurement of at least one of an amplitude, a frequency, and a phase of a cantilever of the operating AFM;
• applying a ΔV between the cantilever and the sample and illuminating the sample with the light source;
• and
• determining at least one of a change in the cantilever amplitude or phase versus the duration of the voltage pulse, the duration of the light pulse, or the relative time delay between such pulses resulting from the applied ΔV and sample illumination.