AFM operating modes

An operating mode is defined by how the tip is driven, what signal is measured and what the feedback loop holds constant. The same array shape can therefore represent different physical observables.

Each mode changes the interaction regime and measured signal. SPM-Kit analyzes resulting files; it does not control these acquisition loops.

Mode comparison

Mode	Physical interaction	Measured/control signal	Advantage	Common limitation/artifact	SPM-Kit scope
contact	repulsive contact, tip remains on surface	deflection or force setpoint	direct, fast, strong signal	lateral drag, wear, sample deformation	reads/analyzes resulting topography and force channels
tapping / intermittent contact	driven oscillation briefly interacts each cycle	amplitude/phase setpoint	lower lateral force; common in air	setpoint/gain artifacts, phase ambiguity, tip convolution	image metrology on resulting channels; no acquisition controller
non-contact / frequency modulation	attractive force gradient shifts resonance	frequency shift or amplitude	gentle; high sensitivity in controlled environments	water layer/environment, long-range-force mixing	reads compatible exported channels; no FM controller
force volume	approach/retract curve at each grid point	force curve per pixel	spatial mechanics/adhesion maps	slow, drift, calibration and fit failures	ForceVolume, force fitting and property maps
quantitative imaging / fast force mapping	rapid force curves at each pixel	peak force/indentation/adhesion route	image + mechanical observables	vendor-specific timing and calibration	limited to demonstrated containers/readers; not universal QI support
KPFM	electrostatic force/force-gradient nulling	DC compensation voltage	surface-potential contrast	sign, capacitive averaging, tip calibration	CPD statistics and work-function calculation from a supplied channel

Contact mode

The controller keeps cantilever deflection near a setpoint. Because the tip is dragged laterally, friction and tip/sample damage can dominate soft materials. Reported height combines scanner response with any residual feedback error.

Tapping and non-contact modes

For a driven damped oscillator, tip–sample forces change amplitude, phase and resonance frequency. Tapping typically uses amplitude feedback and intermittent contact; frequency-modulation non-contact uses a frequency-shift observable. They share oscillator physics but do not produce interchangeable channels.

Force volume and quantitative maps

A force-volume acquisition records approach/retract segments at each grid location. SPM-Kit preserves curve segments and grid shape, then derives maps from per-curve fits. Failed fits, missing lines and calibration uncertainty should remain visible rather than being interpolated into apparent material contrast without disclosure.

Implementation boundary

SPM-Kit is an analyzer, not an instrument controller. The current readers interpret demonstrated exported files. The Core path cannot reconstruct missing feedback settings or decide whether acquisition was physically appropriate.

Route	Core	Fathom	CLI
image/topography	SPMData / image readers	Imagen	info, roughness, analyze
force curve	ForceCurve / force readers	Curva de fuerza	forcecurve, nanomech
force volume	ForceVolume	Mapa	forcemap, forceexport
KPFM channel	kpfm.statistics	Imagen	analyze --tip-wf

Evidence follows the reader and analysis path, not the acquisition-mode label.

AFM principles · Force-distance curves