Europium Bisphthalocyanine—NO 2 Interactions in Monolayers: Spectroscopic and Electrical Measurements

The electronic and surface-enhanced resonant Raman spectra of europium bisphthalocyanine (EuPc₂) are used to monitor the adsorption of NO₂ onto EuPc₂ Langmuir–Blodgett (LB) monolayer films. The reaction was also monitored in solution, and the complex formed was studied by electron paramagnetic resonance (EPR) spectroscopy. Conductivity measurements of the LB film have shown a two-stage process due to exposure to NO₂ gas: adsorption on the surface, and absorption into the film. After a complete desorption by annealing, film conductivity rises continuously with time of exposure to gas to a saturation point. EPR measurements suggest that the EuPc₂ structure is irreversibly changed by the material–gas interaction, although the adsorption is reversible.