Nanoimaging

Nanoimaging refers to a set of imaging modalities capable of visualizing structures at nanometer scales, typically below 100 nm and in many cases down to sub-nanometer resolution. It encompasses techniques that either physically probe a sample or exploit advanced optics and detectors to render nanoscale features with sufficient contrast for interpretation.

Common approaches include electron microscopy such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM), which provide high spatial resolution but require vacuum and substantial sample preparation. Scanning probe microscopy, including atomic force microscopy (AFM) and scanning tunneling microscopy (STM), maps surface topography or electronic properties with atomic-scale precision, often in ambient conditions.

Optical and near-field methods extend nanoimaging to non-destructive imaging of light-sensitive samples. Super-resolution fluorescence techniques such as PALM, STORM, and STED surpass the diffraction limit in living cells, while near-field scanning optical microscopy and other NSOM-based approaches combine confinement of light with nanoscale resolution.

X-ray based nanoimaging, including nano-tomography and coherent diffraction imaging, allows three-dimensional visualization of internal nanostructures, often in non-destructive fashion, with contrast determined by electron density or composition.

Applications span materials science, semiconductors, nanofabrication, catalysis, biology, and nanomedicine. Nanoimaging supports characterization of nanostructures, interfaces, defects, and dynamic processes, aiding design and understanding of nanoscale phenomena.

Challenges include radiation damage, sample preparation artifacts, limited field of view, long acquisition times for high-resolution or 3D imaging, and the need for sophisticated data analysis. Developments aim to enable in situ and operando imaging, correlative approaches that combine modalities, and faster, low-dose techniques.

Outlook: Integration of multiple modalities, improved detectors, and computational methods are expanding the reach of nanoimaging, enabling real-time insights into nanoscale structure and function.