TABLE OF CONTENTS Chemical characterization is to determine the surface and interior atoms and compounds as well as their spatial distributions. As mentioned in the introduction section, many chemical analysis methods have been developed for the surface analysis or thin films, but are readily applicable to the characterization of nanostructures and nanomaterials. Our discussion will be limited to the most popular methods; these techniques can be generally grouped into various optical and electron spectroscopy and ion spectrometry.
Optical spectroscopy has been widely used for the characterization of nanomaterials, and the techniques can be generally categorized into two groups: absorption and emission spectroscopy and vibrational spectroscopy. The former determines the electronic structures of atoms, ions, molecules or crystals through exciting electrons from the ground to excited states (absorption) and relaxing from the excited to ground states (emission). To illustrate the principles of the techniques, absorption and photoluminescence spectroscopy are discussed in this section. The vibrational techniques may be summarized as involving the interactions of photons with species in a sample that results in energy transfer to or from the sample via vibrational excitation or de-excitation. The vibrational frequencies provide the information of chemical bonds in the detecting samples. In this section, infrared spectroscopy and Raman spectroscopy will be used as examples to illustrate the principles of vibrational spectroscopy.
Absorption and transmission spectroscopy. The characteristic lines observed in the absorption and emission spectra of nearly isolated atoms and ions due to transitions between quantum levels are extremely sharp.
