11 



that of TT-JT* excitations and their absorption is shifted towards the 

 shorter wavelength with increasing electropolarity of the solvent, 

 while their fluorescence is quenched by strong acids. The hetero- 

 polar solvent, with its H-bonding, increases the dissociation 

 energy of these electrons which are immobilized by the protons of 

 the strong acid altogether (Kasha, 1950). 



COUPLED OSCILLATORS 



If two systems, capable of similar oscillation, are coupled, then 

 they make "coupled oscillators" and the oscillations will tend to 

 pass back and forth between the two. If, for instance, two penduli 

 of the same periodicity are suspended on the same wire and one 

 of them is put into action, it will soon stop while the other takes 

 over the motion. After a while the second pendulum will pass 

 back the motion with its energy, and so it will go on. 



If A and B are the two penduli and motion is *, then 



A''+B-^A-\-B*-^A*-i-B-^A + B* etc. 



The point about this simple experiment is that the energy com- 

 municated to the one of the two oscillators does not become; 

 divided between the two and thus degraded to lower values, but! 

 is periodically transmitted in its entirety. If there were no friction! 

 and this transmission of energy would occur without loss, motion 

 could go back and forth forever. 



The various atomic groups of the protein are capable of oscilla- 

 tions, vibrations, or rotations comparable to the motion of the 

 penduli. If two such groups with identical frequency are coupled 

 by, say, the polypeptide chain, then they might act as coupled 

 oscillators. It is not impossible that all such groups within the 

 same protein molecule do act as coupled oscillators and so the 

 vibrational energy communicated to one might be taken over by 

 any of them, the whole protein molecule forming one unique 

 system in which the energy communicated to it belongs to the 

 whole, and may appear at any point. 



