An introduction to spectroscopic techniques

In order to understand the principles and applications of spectroscopy in bioanalysis it is important to appreciate some fundamental aspects of waves and electromagnetic radiation. At the heart of spectroscopy, spectrometry and spectrophotometry is the interaction of waves of energy (electromagnetic radiation and non-electromagnetic radiation) and matter in a sample to be analysed. Matter will interact with these waves of energy in different ways, and it is this diversity that is important with respect to identiflcation, analysis and characterization of biomolecules in a sample. 

Characteristically, energy is absorbed, emitted or scattered in the form of waves. These energy waves have certain fixed features that include wavelength and frequency. These values are inversely proportional to each other and can be defined by the following equation  

As the speed of light is a constant, from this equation you can see that the shorter the wavelength (i.e. lower the value of k), the greater the frequency of electromagnetic radiation and the higher its energy. 

In spectroscopy it is useful to consider the propagation of electromagnetic radiation in a quantitative manner. Light is transmitted as discrete packets or as a stream of particles of energy called photons. These photons have a specific energy and for spectroscopy are quantized and described by the following equation  

In spectroscopy, this quantized energy in the form of photons is applied to biomolecules in a sample and energy is exchanged, and the change in energy level of the biomolecule can be measured. 

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