The role of nanowires in advancing X-ray imaging

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Scientific research, medical imaging, and safety surveillance have used x-rays in the past and continue to do so today. Since the introduction of X-rays, the detection of radiation has been a subject of ongoing research; several materials are continuously being developed to detect high performance nanoparticles.

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Generally, the wavelength of observable light ranges from 400 to 700 nm in the visible spectrum. X-rays considered to be high energy have wavelengths less than 0.0110 nm (100,000 eV), which are invisible to humans. Currently, high energy radiation detection methods are in great demand, which makes the development of new methods essential. Some of the traditional methods include x-ray films, phosphorus-based detectors, semiconductor-based detectors, and gas detectors.

The prospect of semiconductor nanowires (NW) as an essential part of nanoscale devices and electronic circuits has given rise to much research over the past decade. Three distinct characteristics of NW fed into previous surveys. First, they simultaneously demonstrate laser guidance and electronic driving capabilities.

Second, their high specific surface area ratio improves their contact with the environment, making them very sensitive. The elastic strain relaxation at the outer surface also allows the construction of new heterostructures which are not possible in plane geometry. Finally, their properties are strongly influenced by their orientation, which makes them suitable for use as polarization dependent sensors.

Nano-sized effects

The materials used in X-ray imaging can be prepared in the form of nanoparticles, nanocomposites or transparent nanoceramics. The use of these materials in X-ray imaging has different effects; some of them are discussed below:

Quantum confinement effect

Quantum confinement occurs when the dimensions of a particle are reduced to the nanoscale due to a drastic decrease in the phases allowed by quantum mechanics in tiny particles, resulting in higher bandgap energy. Optical properties, luminescence endurance and quantum emission efficiency are all affected by this phenomenon.

Surface effect

Compared to larger materials, nanoparticles have a larger area ratio. Since the larger specific surface area frequently contains quenched centers, surface modification is necessary. The Core-shell system is one of the techniques used for this purpose.

Structural effect

Surface tension can cause structural deformation of the crystal structure when the dimensions of materials are reduced to the nanoscale. In addition, compared to large volume bulk voids, the crystallinity and the number of structural defects are decreased within a tiny volume of nanoparticles.

Role of nanowires

Most NW approaches depend on the ability to describe individuals and groups of NW structurally, optically and electrically. At the same time, singular probes that process all of these attributes simultaneously are rare.

The use of synchrotron sensors in the cross-energy spectrum has a lot of potential and offers a variety of advantages, including depths of soil knowledge, element and orbit specificity, and instantaneous availability at edges. absorption K and X fluorescence emission paths of hard, moderate and light elements.

As a result, current types of synchrotron radiation, such as X-ray microdiffraction techniques, have played an important role in the rapid development of nanowire technology. In addition, lensless techniques have been used to analyze ZnO NW using Bragg coherent diffraction imaging.

The ability to follow the full 3D stress tensor with nanoscale precision resolution has the potential to be extremely useful for the study of complex nanostructures. Nevertheless, there are some major drawbacks in this case, due to which information on occurrences of NW is limited.

The majority of synchrotron processes are now carried out in nanoparticle arrays, with data acquired by spatial averaging on a very large scale. Accordingly, for three reasons, the addition of nanoscale spatial resolution capabilities to X-ray imaging in NW surveys is widely desired:

First, the use of powerful nanobeam in x-ray pencils is required to analyze small encrusted areas with signal attenuation and complex structures. Second, thanks to the excellent clarity and low transmissivity of today’s third-generation synchrotron sources, it is now possible to focus X-rays on spot sizes smaller than nanowires using a variety of devices. focus areas such as Fresnel zonal plates and Kirkpatrick-Baez mirrors.

Finally, due to the multiple photon-matter bonds, these X-ray nanoprobes can be used for a range of applications in nanoparticles, including super-sensitive test cases using XRF / XAS, minority phase recognition, and field fields. nanometric precision constrained by XRD.

The chemical characteristics, measurements and stress dispersion of core-shell NW using the grazing occurrence, as well as the dynamics and interactions of the M1-M2 structural phase transformation voltage in each nanowire, the native framework of ‘Single semiconductor, enveloped nanotubes, chemical characteristics, measurements, and stress dispersion of core-shell NW are all examples of using X-ray microbeams to preserve the spatially resolved properties of unique NWs.

Overall, the use of nanomaterials for X-ray detection is limited compared to other applications of nanomaterials. Excitation methods, new scintillator materials, and actual chemical applications are all involved in X-ray detection research using nanomaterials.

Continue Reading: How Can Nanocrystals Size Affect X-ray Diffraction Results?

References and further reading

Cole, MT, Parmee, RJ and Milne, WI (2016). X-ray sources based on nanomaterials. Nanotechnology. 27, 082501. Available at: https://iopscience.iop.org/article/10.1088/0957-4484/27/8/082501

Luoa, Z., Mocha, JG, Johnson, SS and Chenb, CC (2017). A review of X-ray detection using nanomaterials. Current nanoscience. 13 (4): 364 – 372. Available at: https://www.eurekaselect.com/article/82561

Martínez-Criado, G., Segura-Ruiz, J., Alén, B., Eymery, J., & Rogalev, A. (2014). Exploration of single semiconductor nanowires with a hard X-ray multimodal nanoprobe. Advanced materials. 26 (46): 7873-9. Available at: https://doi.org/10.1002/adma.201304345

Wang, C., Zhang, G., Xu, Y., Chen, Y., Deng, S. and Chen, J. (2021). Addressable ZnO Nanowire Cold Cathode Flat Panel X-ray Source with Fully Vacuum Sealed Diode Structure: Manufacturing and Imaging Application. Nanomaterials, 11 (11), 3115. Available at: https://www.mdpi.com/2079-4991/11/11/3115

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