Low-temperature fluorescence and fluorescence excitation spectra of H-
2-tetra-4-tert-butyl phthalocyanine Langmuir-Blodgett films consisting
of well-ordered phthalocyanines in domains and off-domain phthalocyan
ine molecules in random-oriented positions were measured. Persistent s
pectral hole burning was applied to study the role of fast excited ene
rgy transfer from domains to off-domain molecules.