Level location and spectroscopy of image, image, image, and image in image

The spectroscopic properties of image doped with image, image, image, and image under ultraviolet excitation are reported. image host excitation and emission, 4f–5d excitation and emission of image and image, and charge transfer from the valence band to image and image are observed. This experimental information is combined with an empirical model to estimate the position of the lowest 4f and lowest 5d state relative to the conduction band and valence band for each divalent lanthanide ion in image. Existing literature data is used to determine the location of the lowest 4f and lowest 5d state for each trivalent lanthanide.