Description

In scanning probe microscopy (SPM, commonly AFM), the interaction of a stylus probe and sample surface is quantified and mapped across the sample. The probe or "tip" is of nanometer-scale sharpness, and the standard image is 3D surface topography at resolution approaching the atomic or molecular scale. The tip is attached to a microfabricated cantilever of low spring constant. Property-sensitive imaging modes are performed simultaneous to topographic imaging. Gaseous or liquid media, plus sample temperature, can be controlled. Tip chemistry can be modified for controlled studies of probe-sample interaction.

 

Equipment

Scanning Probe Microscope (SPM Station), Digital Instruments Nanoscope V electronics, and optical microscope for tip positioning. Special imaging capabilities include friction force, vertical force modulation with phase measurement, intermittent contact ("tapping") / non-contact with phase measurement, conductive, electrostatic/magnetic force, torsional force, and surface potential. Force Volume imaging is capable in this system. Force Volume is 3D spatial mapping, i.e. the distance dependence of tip-sample interaction over a 2D grid of surface locations (low pixel resolution), in order to characterize adhesion, stiffness or dynamic interaction regimes.

 

 

Applications

Sensitive to the following properties: surface chemistry, storage/loss modulus, hardness, interfacial energy, crystallinity, polarization, magnetization, surface charge, and local work function (surface potential).

Applicable to conductive and non-conductive samples.

Samples can be imaged in air or in liquid media in all modes of operation.

Can measure friction versus load or scan velocity.

Can measure stiffness by nanoindentation.

Can image at heating up to 250ºC and/or cooling to -30ºC.

 

Specifications

No sample pre-treatment needed and imaging can be performed in air.

Sample can be conductive or nonconductive, hard or soft.

Fluid cells available for the SPM station.

Maximum scan size 120x120 µm laterally and 6 µm vertically

Ultimate resolution is 0.1 nm laterally and 0.01 nm vertically; actual lateral resolution depends on sample/tip characteristics (adhesive contact mechanics) and typically is of order 1-10 nm.