1. SPECTROSCOPY Ultraviolet-visible spectroscopy and infrared spectroscopy

2. What is spectroscopy?  The branch of science concerned with the investigation and measurement of spectra produced when matter interacts with or emits electromagnetic radiation  Radio waves are a form of electromagnetic radiation which, like visible light or infrared, make up a portion of the entire spectrum.  They cannot be perceived by human eyes or ears, and they are not harmful in the environment.  Depending on their frequency (measured in hertz), radio waves can pass through solid objects and travel long distances.  This makes them useful for mobile communications, broadcasting and many other wireless applications.

3. Ultraviolet/visible spectroscopy  The wavelength of infrared light is longer than uv/vis. Uv/vis absorption by molecules correspond to differences in the (covalent) bonding of atoms.  Many compounds do not have any visible absorption.  Compounds with metal ions or with (conjugated) double bonds often show uv or visible absorption in a single broad band that can help identify the compound  However, it rarely delivers enough information to identify it unambiguously by itself.

4. Infrared spectroscopy  Infrared absorption by molecules corresponds to differences in vibration energy.  Infrared spectroscopy can therefore be used to identify molecular vibrations and uniquely recognize compounds.  Compounds consisting of more than a handful of atoms have very many narrow infrared absorption bands. The wavelength of infrared light is longer than uv/vis.