Spectral diffusion and thermal recovery of spectral holes burnt into a phthalocyanine doped Shpol’skiĭ̌ system

Abstract

We measured thermally irreversible line broadening features of photochemical holes burnt into a phthalocyanine doped Shpol’skiǐ crystal. The broadening, as obtained from temperature cycling hole burning experiments is significant, indicating that irreversible structural changes do occur in Shpol’skiǐ matrices. Different sites show a different behavior. As far as line broadening is concerned, the observed features are similar to glasses. The thermal recovery curve of the holes, however, differs very much from glasses. It can be fitted by a bimodal Gaussian distribution. This bimodal distribution is interpreted in terms of two categories of photoproduct states, which the phthalocyanine molecule can possibly occupy: In category one, the two inner protons are neighbors in category two, they are diagonal.