The document discusses various characterization techniques used to analyze nanomaterials. It begins by providing historical context on the origins of nanotechnology and then describes several microscopy and spectroscopy methods. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, small angle X-ray scattering, and scanning probe microscopy are some of the key techniques explained in the document.

1. Characterization of Nanomaterials Estareja, Rogel Lindolf B.

2. How did it all start? Professor Richard Feynman presented the idea of manipulating and controlling things on an extremely small scale by building and shaping matter one atom at a time. Feynman described how the 24 volumes of the Encyclopedia Brittanica can be written on the head of a pin. He said that letters could be represented by six to seven bits of information for each letter. He also suggested using the inside as well as the surface of a metal to store information. Feynman allowed that if each bit was equal to 100 atoms, all the information of all the books of the world could be written in a cube of material 1/200 inch wide, about the size of a tiny speck of dust. THERE IS PLENTY OF ROOM AT THE BOTTOM!

3. Nanotechnology In 1989, Don Eigler of IBM formed the letters of the company from 35 xenon atoms by STM.

4. Optical Microscopes are not for nanoscale analysis? “The smallest resolvable distance between objects is about half the wavelength of the light used” So, for visible light (500nm), resolving power is about 250 nm only! Nanomaterials (<100 nm) would appear blurred or undistinguishable. Only wavelengths from UV, X-ray, up to Gamma are applicable for visual characterization.

5. Using Electron beam By de Broglie wave equation

7. BackscatteredElectrons –produced by Elastic scattering of Core electrons and having the same energy as the primary electrons. Responsible for CONTRAST.

11. SEM vs TEM Scanning Electron Microscope Samples must be conductive or else it will BURN! Im in 3D! Over 300k times magnification Transmission Electron Microscope Samples must be thin enough or else it wont project a recognizable image! Just 2D. Up to 1million times magnification

15. How Scanning Probe Microscopy Works?

16. Scanning Tunneling Microscopy STM uses the a quantum physics phenomenon called “Tunneling” to provide detailed images of substances that can conduct electricity. The probe is brought to within a few angstroms of the surface of the material, and a small voltage is applied between the surface and the probe. Because the probe is so close to the surface, electron leaks, or tunnel, across the gap between the probe and surface , generating current.

17. The strength of the tunneling current depends on the distance between the surface and the probe. If the probe moves closer o the surface, the tunneling current increases, and if the probe moves away from the surface, the tunneling current decreases. As the scanning mechanism moves along the surface, the mechanism constantly adjusts the height of the probe to keep the tunneling current constant. By tracking these minute changes, a computer can create a 3-D representation of the surface.

18. Atomic Force Microscopy As the metal probe in an AFM moves along the surface of a sample, the electrons in the probe are repelled by the electrons of the atoms in the sample and the AFM adjusts to the height of the probe to keep the force on it constant. By the up-and-down movements of the probe, a computer can track and make a 3-D image of the surface sample

20. Characterization depends on the type of the interactions between the tip and the sample surface.

22. The Tiniest Wires An image from a STM reveals wires on eight to ten atoms wide. Researchers at Hewlett-Packard Company in Palo Alto, California, developed the nanowires, the tiniest wires yet created.

24. Physical Adsorption is particularly useful in the determination of specific surface area and pore volume in mesopores (2~50nm) or micropores (<2nm).

27. The core hole thus created may get filled by electron de-excitation resulting in X-ray.

28. All photons (X-ray) emitted by the sample are collected and measured simultaneously by a solid-state X-ray detector

32. When the emission is resulted from electronic stimulation, it is referred as cathodoluminescence.

37. Chemical characterization Techniques

38. References Nanotechnology Demystified -Linda Williams & Wade Adams NANO: The Essentials (Understanding Nanoscience and Nanotechnology) - T. Pradeep Nanostructures and Nanomaterials (Synthesis, properties & applications) - Guozhong Cao