Strong absorption bands Large electric transition dipole moments

Of course, the situation is somewhat more complex. The rotational strength of the (th transition, Ri, is the result of / , coupling with all of the other transitions in all of the adjacent chromophores, i.e.. 

If the two wavelengths. A,- and Aj, and the two chromophores are very close, however, the denominator of these two terms, R and Rjt, becomes quite small and these terms can dominate in the summations for Rj and Rj. This has been demonstrated in a number of dinucleotide prosthetic groups of enzymes, such as flavin-adenine dinucleotide and nicotinamide-adenine dinucleotide. An example is given below for the adenine and nicotinate chromophores. 

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