Luminescence of self-trapped excitons induced by single keV ion bombardment

Abstract

We have studied the light emission from CsI and NH 4Cl films that were bombarded simultaneously with H −, low mass organic, and (CsI) n I − ( n = 0–2) ions in the keV energy range (25–45 keV) at room temperature. Photons were detected from the impact of individual primary ions with a single photon counting photomultiplier, and were analyzed using time resolved and wavelength analysis. For CsI, fast ( τ ≤ 12 ns) and slow ( τ ≥ 650 ns) component decays were observed for all projectiles used. The fast component's emission was ∼ 300 nm while the slow component's emission was in the visible. Only a fast component ( τ < 3 ns) was observed in the UV region for NH 4Cl. Our data suggest that the light emission from both samples is due to the radiative relaxation of self-trapped excitons which are produced by electronic interactions between the primary ions and the target atoms.