Infrared fight spectra

The images that are generated by STM and AFM show structure but no true chemical composition. The details of the local chemistry on surfaces at the nanoscale level, however, are very important to understanding surface properties. Optical spectroscopy and microscopy provide a means of chemically identifying materials in conventional microscopy, however, the resolution limit is approximately half the wavelength of the fight used to illuminate the sample. Thus, spatial resolutions are typically limited to approximately 200 nanometers (7.9 X lO inches) in the visible and approximately 5,000 nanometers (2.0 X 10 inches) in the infrared parts of the electromagnetic spectrum. 

The light-emitting diode (LED) is a semiconductor device that emits incoherent, narrow-spectrum light. The color of the emitted fight depends on the semiconducting material used, and can be near-ultraviolet, visible or infrared. 

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