Provmikroskopi

Provmikroskopi, or probe microscopy, refers to a family of scanning probe techniques that map surface structure and properties by moving a sharp probe over a sample. The methods rely on a physical interaction between the probe tip and the surface and are capable of operating in air, vacuum, or liquid. They can image conductive samples, and in many modes, insulating or biological specimens as well.

Scanning tunneling microscopy (STM) uses a conducting tip brought very close to a surface. A bias voltage induces tunneling current between tip and sample, and the current is extremely sensitive to distance. A feedback loop adjusts the tip height to keep the current constant, producing an image with atomic-scale resolution that reflects the local electronic structure of the surface.

Atomic force microscopy (AFM) uses a cantilever with a sharp tip that deflects under interatomic forces as the tip scans the surface. A laser and detector measure cantilever deflections. Mode choices include contact, non-contact, and tapping (intermittent contact), each providing different contrasts and suitable for different sample types. AFM can image non-conductive materials and, with appropriate modes, measure mechanical, electrical, magnetic, or chemical properties.

Instrumentation commonly includes a sharp probe, a piezoelectric scanner for precise x-y-z movement, vibration isolation, and a feedback system. Image formation is influenced by tip geometry (tip convolution) and by the interaction regime chosen. Provmikroskopi enables nanoscale imaging and characterization in diverse fields, including materials science, nanotechnology, catalysis, and biology, often under conditions that preserve samples in realistic environments.