Spectroscopy Raman

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spectroscopy
Spectrograph
Spectrophotometer
Diffraction Grating
Spectrum Analysis
Continuous Spectrum
Spectrum Lines
Work of Niels Bohr
Absorption Spectra
Applications of Spectrum Analysis
Chemical analysis
Astrophysical applications
In physics and physical chemistry, the study of spectra (see Spectrum). The basis of spectroscopy is that each chemical element has its own characteristic spectrum (see Elements, Chemical). This fact was recognized in 1859 by the German scientists Gustav Robert Kirchhoff and Robert Wilhelm Bunsen. They developed the prism spectroscope in its modern form and applied it to chemical analysis. One of two principal spectroscope types, this instrument consists of a slit for admitting light from an external source, a group of lenses, a prism, and an eyepiece. Light that is to be analyzed passes through a collimating lens, which makes the light rays parallel, and the prism; then the image of the slit is focused at the eyepiece. One actually sees a series of images of the slit, each a different color, because the light has been separated into its component colors by the prism. The German scientists were the first to recognize that characteristic colors of light, or the spectra, are emitted and absorbed by particular elements.

Spectrograph
In a spectrograph, the eyepiece is replaced by a camera. Color photography is not necessary to identify the images of the slit, known as the spectrum lines; their wavelengths can be calculated from their positions on the film. Spectrographs are useful throughout the ultraviolet and visible regions of the spectrum, and as far as 1200 m (0.000048 in) in the infrared region. Spectroscopy in the extreme ultraviolet and infrared regions is similar to that in the visible region, except that glass does not transmit such radiations; lenses and prisms are made of quartz, flourite, sylvine, or rock salt. Concave mirrors can also be substituted for lenses. Special p...