PHYS01200704032 Debes Ray - Homi Bhabha National Institute

Chapter 3: Multi-Technique Approach for Characterization of Gold Nanoparticles
believed to be due to the changes in the dielectric nature (modification of the refractive
index) surrounding the nanoparticles after the formation of ligand layer on the surface of the
gold nanoparticles [163,164,168].
Figure 3.4. The change in UV-visible spectra of gold nanoparticles on their conjugation with
ligand.
3.3. Transmission Electron Microscopy
For the study of structure and morphology of nanomaterials with magnifications down to the
atomic scale transmission electron microscopy is an important direct method. TEM uses
electrons instead of light waves to generate magnified images. It has higher resolution than
optical microscopes (due to ∆λ) and allows one to visualize objects that are as small as 1 nm,
hence atomic resolution is possible. In this way, it bridges the 1 nm - 1 μm gap between X-
ray diffraction and optical microscopy [54,160,169,170].
3.3.1. Experimental Details
In transmission electron microscopy, a beam of electrons is passed through the sample with
high accelerating voltage. It uses magnetic lenses to deflect the electron beam where the
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