26 



Absorption Spectrophotometry 



I. Roie of Absorption Spectrophotometry in 

 Biology 



Absorption spectrophotometry plays an important role in many areas of 

 biophysical research. The techniques and equipment used have been 

 specialized and developed to be increasingly more precise and more 

 versatile. This special physical equipment allows one to extract infor- 

 mation from biological systems which would otherwise keep their 

 secrets from the investigators. In contrast to the previous chapter, 

 which dealt with the description of information in the language of 

 information theory, the current chapter describes equipment used to 

 obtain information. 



Electromagnetic spectra have been important in many areas of 

 natural science. For example, the characteristic emission spectra of 

 light radiated from atoms formed one of the major parts of the supporting 

 evidence that led to the development of the theory of quantum mechanics, 

 an important field of modern physics. Characteristic absorption spectra 

 have played an equally important role in modern physiology, bio- 

 chemistry and biophysics. Spectroscopy can reveal far more than can 

 most chemical tests ; these show only the general class to which a com- 

 pound belongs. In biological systems, there are many similar mole- 



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