Fluorescence properties of chlorophyll a and b monomolecular films at the air-water interface

The fluorescence properties of chlorophyll $\text{a}$ and $\text{b}$ monomolecular films at the air-water interface were measured by a high sensitivity fluorophotometer using the photon-counting method. The fluorescence intensity of chlorophyll molecules in monomolecular films in the absence of any diluents did not decrease simply with the mean distance of chlorophyll molecules. Over the range of the mean distances from 27 to 21 Å, three fluorescence components (peaks at 685, 695 and 715 nm) of chlorophyll $\text{a}$ were observed. In the case of chlorophyll $\text{b}$, two fluorescence components (peaks at 667 and 685 nm) were observed over the range of the mean distances from 34 to 24 Å. When the mean distance was 18 Å, the short wavelength component of chlorophyll $\text{b}$ disappeared, and only the long wavelength component was observed.