ENHANCEMENT OF NONPHOTOCHEMICAL HOLE-BURNING BY 2-COLOR EXCITATION INPOLYMERS CONTAINING CARBOXYLIC-ACID

We report that persistent spectral holes are formed 1.3-3.0 times more efficiently when the guest molecules (Zn porphyrin derivative) are ex cited by two colors than by one color alone in the matrices containing carboxylic acid. The deuteration of carboxylic acid reduces the enhan cement of hole formation by two-color irradiation. The two-color enhan cement is observed only when the matrix contains carboxylic acid group s. The better thermal stability of the two-color holes indicates that a different mechanism proceeds in the presence of carboxylic acid grou ps from the case of usual nonphotochemical hole burning with hydroxyl groups. Hydrogen bond tautomerism of carboxylic acid dimers is a propo sed mechanism for the two-color hole burning.