A processing system cooperates with an atomic force microscope operating in ramp mode at a ramp frequency is configured to collect data indicative of at least one of physical and chemical properties of a sample. The system collects data indicative of probe movement at a frequency that is higher than the ramp frequency. This data comprises a second-order portion of the probe's signal. Based at least in part on the second-order portion, the processor obtains a parameter that is indicative at least one of a physical and a chemical property of a sample.