Q-band splitting and relaxation of aluminum phthalocyanine tetrasulfonate

The doublet band structure evident in the fluorescence excitation and absorption spectra of aluminum phthalocyanine tetrasulfonate in various hyperquenched glassy solvents is attributed to splitting of the Q-band transition into x and y components. The splitting is caused by the ligation of water molecules to the aluminum atom which decreases the molecular symmetry. Picosecond relaxation from the Qy band to the Qx band is evident in the hole burned spectra.