Observation of Polarization-Dependent Spectral Holes in an Organic Thin Film

Using time-resolved pump-probe spectroscopy, we have studied room-temperature spectral hole burning in an organic fluoroaluminum phthalocyanine (FA1Pc) polycrystalline thin film. The spectral hole is observable only when the pump and probe polarizations are parallel. The sublimed, ≈0.2-μm-thick FA1Pc thin film consists of phthalocyanine rings containing delocalized, conjugated π-electron systems The resulting thin-film Q-band absorbance spectrum is shown by the dashed line in Fig. 1.