Potential of Spectroscopic Techniques in the Characterization of "Green Nanomaterials"

Nanomaterials are miniaturized particles of range 10⁹ with the dimensional size of 1-100nm. Biologically derived nanoparticles synthesized from living organisms such as plant, algae, fungi, and bacteria have gained greater importance in the modern era in the fields of medical and industrial applications. As compared to chemically derived nanoparticles, green nanomaterials are simple, stable, cost-effective, eco-friendly, and less hazardous. The uniqueness in physiochemical, optical, electrical, and crystallographic properties of nanoparticles is mainly governed by the particle size, shape, and crystallinity. Because of the large surface-to-volume ratio of nanoparticles, they can easily interact with other particles. Nanoparticles have a wide range of applications, including catalysis (Cu nanoparticles), imaging (carbon nanoparticles for cell trafficking), drug delivery vehicles (silver nanoparticles), sensing (quantum dots), and environmental protection (fullerene nanoparticles; C60).The various innovative applications of nanoparticles to do everything can only be realized when molecular structure along with conformational dynamics is fully elucidated at the atomic level. Spectroscopy that utilizes radiation intensity as a function of wavelength can be used to detect and quantify atoms and molecules both qualitatively and quantitatively. Examples of commonly used methods are nuclear magnetic resonance (elucidation of function groups attached to nanoparticles), Raman scattering (based on vibrational motion of chemical bonds), circular dichroism (based on absorptions of circularly polarized light by asymmetric molecules), and mass spectrometry (utilizing mass-to-charge ratios for elemental composition determination); other examples are X-ray scattering, zeta-potential measurements, and UV-visible absorbance spectroscopy. In this chapter, we present a comprehensive overview of the methodology for characterization of nanomaterials based on a spectroscopic approach.