Changes in the surface electronic states of quantum-sized semiconductor particles induced by high energy proton irradiation?

We performed steady-state and time-resolved measurements of the ion- induced emissions and photoluminescence (PL) measurement on quantum-sized semiconductor particles prepared in Langmuir-Blodgett films. The proton irradiation caused a decrease in intensity of the emission via trapping sites, removing almost all the traps in the band gap. The low energy emissions, which showed a multiexponential decay, are considered to originate from a recombination of donor-acceptor pairs localizing in the surface region. Furthermore, PL spectra obtained after the irradiation changed drastically in the course of the photo-oxidation of the particles.