Fig. 1: Photoluminescence emission spectra.
From: Broadband infrared LEDs based on europium-to-terbium charge transfer luminescence
Photoluminescence emission spectra of Eu2+- and Tb3+-codoped CaS (a) and SrS (b) phosphors. The spectra were collected upon 285 nm excitation for the Eu- and Eu/Tb-codoped powders and upon 305 nm excitation for the Tb-doped powders. The spectral shape of the infrared metal-to-metal charge transfer (MMCT) emission is highlighted in yellow as a guide to the eye. All spectra were measured at room temperature.
