Comparing the effect of electron beam, beta and ultraviolet C exposure on the luminescence emission of commercial dosimeters

This paper reports on the luminescence characterization of TLD-100 (LiF: Ti, Mg), TLD-200 (CaF₂: Dy), TLD-400 (CaF₂: Mn) and GR-200 (LiF: Mg, Cu, P) dosimeters exposed to electro beam, beta and ultraviolet C radiation -UVC-. All of them show high sensitivity to radiation regardless of whether it is ionizing or partially ionizing radiation based on their luminescence properties (cathodoluminescence -CL- or thermoluminescence -TL-). CL emission differs significantly among them in shape and intensity due to their chemical compositions. LiF samples display three maxima at: (i) 300-450 nm linked to intrinsic and structural defects, (ii) a green waveband probably due to F₃⁺ centres or the presence of hydroxyl groups and (iii) the red-infrared emission band associated with F₂ centres. However, CL spectra from the CaF₂ dosimeters display meaningful differences due to the dopant. TLD-200 is characterized by an emission with four sharp individual peaks in the green-IR spectral region (due to the Dy³⁺), whilst TLD-400 exhibits a broad maximum peaked at ̴500 nm (linked to the Mn²⁺). On the other hand, the variation in the TL glow curves allows to discriminate the TLDs exposed to beta and UVC radiation since they give rise to different chemical-physical processes and that have been studied from the estimation of the kinetic parameters by means of the Computerised Glow Curve Deconvolution (CGCD) method.

Red emission material from Eu3+ ion doped in oxy-fluoroborate glass system

The aim of the work is to prepare (51-x)B₂O₃ + 23CaF₂ + 10Li₂O + 10Na₂O + 6BaO + xEu₂O₃ glasses with various concentration, analyse the optical/radiative properties and compare with other reported literature. In this work, the Judd-Ofelt analysis was employed to evaluate oscillator strength, JO parameters. Using JO parameters, radiative properties of the prepared samples were evaluated to understand their branching ratios, stimulated emission cross-section and radiative lifetime. The phonon coupling constant was evaluated using phonon sideband and compared with other literatures. The present glasses doped with Eu³⁺ ions find a potential use in orange red light emitting optical display device applications.

Fluorescence resonance energy transfer of CaF2: Eu2+, Tb3+ applied to dye-sensitized solar cells

CaF₂: Eu²⁺, Tb³⁺ introduced into dye-sensitized solar cells (DSSCs) were studied to examine the influence of luminescent materials on photoanodes using a simple method. The emission spectra of CaF₂: Eu²⁺, Tb³⁺ included the blue light of Eu²⁺ (4f → 5d) at 430 nm and green emission of Tb³⁺ (⁵D₄ → ⁷F₅) at 542 nm under the monitoring wavelengths at 398 nm, which matched well the absorption range of the N719 dye in DSSCs. Energy transfer (ET) was verified between Eu²⁺ and Tb³⁺ ions and the efficiency of ET found to increase with Tb³⁺ concentration. Both the fluorescence resonance and luminescence-mediated ETs between phosphor and N719 dye were observed as the main contribution in improving photocurrent and power conversion efficiency (PCE) of these DSSCs. The PCE of DSSCs doped with phosphors was greatly increased by 5.16, to 43.3%, which was comparable to cells made of pure TiO₂ photoanodes. Moreover, CaF₂: Eu²⁺, Tb³⁺ enlarged the surface area of TiO₂ photonaodes, which helped the adsorption performance of the TiO₂ film.