EFFICIENT PERSISTENT SPECTRAL HOLE-BURNING OF FREE-BASE OCTAETHYLPORPHINE ADSORBED ON GAMMA-ALUMINA BETWEEN 1.6-K AND 90-K

We have used persistent spectral hole-burning to investigate free-base octaethylporphine (OEP) physisorbed on gamma-alumina. This system combines the efficient photochemical hole-burning mechanism of free-base porphines with the idea of decoupling the chromophores from the surrounding by using surface attached chromophores. Hole formation of this system is very efficient and very deep holes (> 70% depth) can easily be burnt. The system shows high thermal hole stability. A hole with a hole depth of 17% can be burnt at 90 K and holes burnt at 2.5 K recover after being held at 120 K for 30 min. The temperature dependence of the Debye-Waller factor is very weak. Depending on the excitation wavelength various photoproducts can be generated. The hole-burning mechanism is discussed.