Effect of pH on Absorption and Fluorescence Spectra

Positions and relative intensities of absorption and fluorescence bands of porphins. 

The neutral porphin has one main and three weak fluorescence bands whereas the acid form has three prominent fluorescence bands (Fig. 10). Studies of Dher6 (23,24) have revealed a whole series of still weaker fluorescence bands extending into the infrared. The solid porphins have absorption spectra shifted toward longer wave lengths, and they show emission spectra also displaced to the red (e.g., solid etioporphin. Fig. 10). 

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