Spectroscopic Investigations 

 of Luminescent Systems 



C. J. p. Spruit and A. Spruit-van der Burg 

 Landbouwhogeschool, Wageningen, Holland 



The present discussion stems largely from the work carried out by 

 the Biophysical Research Group at Utrecht during the period 1935- 

 1947. At the organization of this group, the subject of biolumi- 

 nescence was chosen by the directors, Prof. Dr. A. J. Kluyver and the 

 late Prof. Dr. L. S. Omstein, as a promising field for the application 

 of physical methods to biology. During the preceding period, impor- 

 tant conclusions had been drawn from the study of the spectroscopic 

 properties of atoms and simple molecules. It was therefore considered 

 advisable to make use of the experience which had been obtained in 

 the Physical Laboratory at Utrecht with methods of spectral energy 

 measurements, for the study of the emission spectra of bioluminescent 

 phenomena. 



It was hoped that a detailed knowledge of the spectral energy 

 distribution of bioluminescent emission might lead to conclusions as 

 to the architecture of the molecules involved. It is true that during the 

 following years, the increasing insight into the physics of hght absorp- 

 tion and emission by more compUcated molecules has considerably 

 tempered this initial optimism. 



The theoretical difficulties encountered during the attempt to for- 

 mulate the connection between chemical structure and spectroscopic 

 properties of organic molecules have been overcome only in some 

 relatively simple cases even now. To these theoretical difficulties 

 should be added the fact that in the case of organic molecules in 

 solution, the ultraviolet and visible absorption spectra are of a diffuse 



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