Shape elongation of Zn nanoparticles in silica irradiated with swift heavy ions of different species and energies: scaling law and some insights on the elongation mechanism.

摘要: Zinc nanoparticles (NPs) embedded in silica were irradiated with swift heavy ions (SHIs) of seven different combinations species and energies. The shape elongation induced by the irradiations was evaluated optical linear dichroism (OLD) spectroscopy, which is a sensitive tool for determining change mean aspect ratio (AR) NPs. Although AR indicated fluence dependence low- medium-fluence regions, it nonlinear high-fluence region. data reveal that efficiency Zn correlated electronic stopping power ‘Se silica’ not either Zn’ or nuclear power. plotted as function revealed relationship, threshold value ∼2 keV nm−1, same exhibited ion-track formation silica. log–log plot showed increased linearly Se above critical ∼3 nm−1 steeply decreased to 5 below Se. steep decrease can be ascribed discontinuous nature ion tracks, expected at Se ∼ 2–4 Φ dependences AR − 1 under various are well-normalized energy deposition SHIs, i.e., product Φ, greater than nm−1. normalized fell on relation, AR(Φ) − 1  ∝ SeΦ, SeΦ   2 nm−3. On basis these experimental results, we discuss some insights into mechanism.