Visualization of Nanostructures

It is very crucial that nanostructures in both biomedical and scientific research although this may be very challenging. Nanostructures is a structure that is of an intermediate size ranging from molecular and microscopic structures. There has been tremendous progress over the last few years in relation to the visualization of macromolecules that are biologically important using various techniques. Visualization of nanostructures is very important since visualization aids in having a better understanding of this structure and we can also be able to link the visualized structures to the functions that they perform. Below are some of the techniques that have been used in the visualization of nanostructures.

X-ray Computed Tomography

Since the 1960s, computed tomography has been there.  In images of a patient that are planar projected, there may be details that are hidden by tissues that over-laying. Through the use of slice-imaging techniques such as tomography, a demonstration that is selective, that is, layer by layer is possible. The most ideal form of tomography is computerized tomography that yields images in a sequence of the patient’s thin consecutive slices and it also offers the opportunity three-dimension localization.

The x-ray images of the objects are taken from various angles and direction and then a computer generates an image of the object that is three-dimensional using the given images. Contrast is generated through differential absorption of x-rays in materials that are dissimilar and this makes the visualization of nanostructures possible.

X-ray Diffraction microscopy

When it comes to the analysis of composition profiles and strain field of matter that is condensed, x-ray diffraction is an excellent non-destructive tool to use for better understanding of novel properties in relation to small size, local probes have been gaining popularity and this is as a result of the development of structures that are very small for Nano and microelectronics.  To be able to visualize nanostructures, a scanning x-ray diffraction microscopy is used and this approach is a combined focused x-ray beam and x-ray diffraction so as to be able to localize the nanostructures and to carry out analysis of their composition and strain.

 In most cases, the volume probe needs to be adopted to the feature size and this ranges from micrometres to even smaller size than that. Individual objects can be identified and probed one by one through the use of epitaxial semiconductor islands. 

Field-emission Scanning Electron Microscope

This technique has been applied by various researchers in physics, biology and chemistry for the observation of very small structure that cannot be observed using the naked human eyes. The FESEM functions by liberating electrons from a field emission source and then the electrons are accelerated in an electrical field gradient that is very high. The primary electrons in the high vacuum column are then focused and deflected through the use of electric lenses that generate a scan beam that is very narrow which then bombards the objects.

This then results in the emission of secondary electrons each spot that is located in the object. The velocity and angle of the secondary electrons directly relate to the object’s surface structure. A detector then takes hold of the secondary electron and generates an electric signal which then is amplified and transformed. This then produces a video scan image that can be observed on a digital image or monitor which can then be saved and further processed if necessary.

Transmission Electron Microscope

This is a microscopy technique where there is the transmission of a beam of electron via a specimen to generate an image.  Interaction of electrons with the sample during the transmission of the electron via the specimen results in the formation of an image. The resultant image is then magnified and focused onto a device that does the imaging such as a photographic film, a fluorescent screen or a sensor like a scintillator that is attached to a device that is charge-coupled.  As a result of the small de Broglie wavelength, the transmission electron microscope has the capacity of imaging objects at a resolution which is higher as compared to a light microscope. 

There are numerous arrays of modes of operation of the electron transmission microscope such as scanning TEM imaging(STEM), spectroscopy, convectional imaging, diffraction and a combination of all these and this makes it easier to visualize nanostructures. This makes it possible for the instrument to be able to capture details which are very clear even though the structures may be very small. The transmission electron microscope has been used as a major analytical technique in the analysis of biological, chemical and physical elements.

As challenging as it may be to visualize nanostructures, understanding how essential it is to visualize nanostructures, various techniques have been developed making it possible to have a better and clear observation of the size, shape and other details in relation to the nanostructure. This has greatly helped researchers to link the observed structures to how these structures function.