Hole-burning spectroscopy of a Langmuir-Blodgett monolayer of etioporphyrin and octaethylporphyrin

Abstract

Langmuir-Blodgett (LB) mixed monolayers of octaethylporphyrin (OEP) and etioporphyrin I (EI) and arachidic acid were transferred to glass slides and glass slides coated with a silver island film. Persistent spectral holes in the region of the S 1←S 0 electronic transition of a single LB monolayer of OEP and EI were observed at 4.2 K. No significant differences between holewidths of a monolayer on glass and of a monolayer on a Ag island film were observed. From the measurements of the holewidths it was concluded that the homogeneous width of the S 1←S 0 electronic transition of both OEP and EI in LB films should be less than 0.5 cm −1. The bandwidth measured in the absorption spectra were 42 cm −1 and ca. 150 cm −1 for OEP and EI respectively. The large FWHM values were attributed to inhomogeneous broadening. The electronic spectra of OEP and EI monolayer (measured at 4.2 K) were not significantly changed by the presence of the Ag island film. Surface enhanced Raman scattering and fluorescence spectra were also measured.