In situ study of light emission from SiO2 irradiated by medium energy Xeq+ ions

Silicon dioxide (SiO2) is a candidate material for fusion applications, in magnetic and inertial concepts. Due to its special physical and chemical characteristics, it is used in many different technology fields like optics, electronics, energy orspace. Swift heavy ion irradiation can modify the crystal structure and optical property of optical material SiO2. Swift heavy ions deposit their energy mainly by inelastic interaction. Highly ionized lattice atoms may be formed along the trajectory and a fraction of their electrical energy can be transformed directly into the kinetic energy of the ions. The irradiation experiment was performed with Xeq+ ions at the irradiation terminal of the Sector-focused Cyclotron at Heavy-ion Research Facility in Lanzhou (HIRFL). The on-line spectral measurement experiment was carried out during irradiation. In the darkroom, the UV-visible light emission from the target was focused into optical fiber by a collimating lens, and then was analyzed with the Sp-2558 spectrometer equipped with a 1200 g/mm optical grating blazed at 500 nm. In the present work, SiO2 single crystals are irradiated with 93 - 609 MeV Xeq+ ions for the dose in the range of 1×1011 - 3×1011 ions/cm2. During irradiation, the emission spectra, in the range of 200 - 800 nm, from SiO2 irradiated by 93, 245, 425 and 609 MeV Xeq+ ions, are obtained. Two emission bands centered at 461 and 631 nm are observed. These emission bands are produced by Frenkel exciton radiation de-excitation and their intensity is closely related to the irradiated ion energy and radiation dose. The results show that the light intensity increases with the electron energy loss index. And due to crystal damage caused by ion irradiation, the intensity of emission spectrum decreases with increasing irradiation dose. Ion loses its energy throughout the ion track via Sn and Se while interacting with target atoms and electrons respectively, and are estimated using SRIM code. SRIM simulated ion ranges and recoil atom distribution, target ionization (energy loss to target electrons), damage production in SiO2 is present. Based on the energy deposition process, the emission bands related to the crystal structure itself are discussed. It indicates that electron energy loss plays a leading role in the process of light emission. In-situ measurement of the optical emission is of great significance to study the irradiation modification and can help to understand the process of crystal damage caused by ion irradiation.