Rahman A*, Rahman AK, Yamamoto T and Kitagawa H
Terahertz sub-surface imaging offers an effective solution for surface and 3D imaging because of minimal sample preparation requirements and its ability to “see” below the surface. Another important property is the ability to inspect on a layer-by layer basis via a non-contact route, non-destructive route. Terahertz 3D imager designed at Applied Research and Photonics (Harrisburg, PA) has been used to demonstrate reconstructive imaging with a resolution of less than a nanometer. Gridding with inverse distance to power equations has been described for 3D image formation. A continuous wave terahertz source derived from dendrimer dipole excitation has been used for reflection mode scanning in the three orthogonal directions. Both 2D and 3D images are generated for the analysis of silver iodide quantum dots’ size parameter. Layer by layer image analysis has been outlined. Graphical analysis was used for particle size and layer thickness determinations. The demonstrated results of quantum dot particle size checks well with those determined by TEM micrograph and powder X-ray diffraction analysis. The reported non-contact measurement system is expected to be useful for characterizing 2D and 3D naomaterials as well as for process development and/or quality inspection at the production line.
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