Several advanced techniques are employed for nanoscale imaging, each with its unique advantages and limitations:
Scanning Electron Microscopy (SEM)
SEM uses a focused beam of electrons to scan the surface of a sample, producing high-resolution images. It is particularly useful for examining the surface topography and composition of nanomaterials.
Transmission Electron Microscopy (TEM)
TEM involves transmitting electrons through a very thin sample. This technique provides detailed information about the internal structure of nanomaterials, including atomic arrangements and defects.
Atomic Force Microscopy (AFM)
AFM uses a cantilever with a sharp tip to scan the surface of a sample. The interaction between the tip and the sample surface is measured, generating topographic maps with atomic resolution. AFM is versatile, as it can image a variety of materials, including biological samples.
Scanning Tunneling Microscopy (STM)
STM measures the tunneling current between a sharp conducting tip and the sample surface. This technique provides atomic-scale resolution and can be used to manipulate individual atoms and molecules on a surface.
Near-Field Scanning Optical Microscopy (NSOM)
NSOM overcomes the diffraction limit of light by using a small aperture to scan very close to a sample. It combines high spatial resolution with the ability to perform optical spectroscopy.
