Nanoscale Tools and Instruments.
To observe matter at the nanoscale it is necessary to use instruments that have probes that are smaller than the wavelength of visible light. 4 Several types of Electron Microscopes that can magnify samples from 10 to 1,000,000 times using the energy from electrons are used to observe nanoscale matter. Three types of electron microscopes used include the Scanning Electron Microscope (SEM), the Transmission Electron Microscope (TEM), and the Analytical Electron Microscope (AEM). The SEM scans the surface of thick or thin samples using a focused beam of electrons. 5 The TEM sees through a sample facilitated by a wide beam of electrons that pass through a thin slice of a sample forming an image with a 3-D appearance. 6 The AEM is built to look inside materials at a high magnification. The AEM provides very high-resolution images and information on a material's atomic composition, molecular bonding, and electrical conductivity. Using this microscope, researchers can obtain detailed information on the molecular makeup of nanomaterials, data on specific properties, and the performance of structures made from them. 7
Scanning Probe Microscopes are another category of microscopes used to study the surface character of atomic-scale and nano-scale materials. They have a fixed or mounted probe tip/stylus on the end of a tiny beam. Some of the microscopes in this category include the Scanning Tunneling Microscope (STM), the Atomic Force Microscope (AFM), and the Laser Scanning Confocal Microscope (LSM). The STM uses a fixed probe tip to measure a material's surface electrical characteristics. "A tunneling current is created when the sharp conducting tip is placed very close to a conducting surface with a voltage difference between them." When the tip moves up and down it tracks and records the surface of the sample. 8 The AFM uses a mounted probe tip on a flexible laser beam. The ridges and valleys of the samples surface cause the probe tip to raise and lower as it drags across the surface. It can operate in contact or non-contact mode. The quality of the resolution of the image is determined by the sharpness of the probe's tip. 9 The LSM uses ultraviolet laser light and scanning mirrors that sweep across a sample. Several single slice images are pieced together by a computer to create a three dimensional image on a computer monitor. This microscope has the ability to create high-resolution images. 10
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