Two-photon excitation to image configuration of image in image crystal by KrF excimer laser

The two-photon excitation to high-lying levels of image via the intermediate image levels in image and image crystals has been studied under pumping by 248 nm radiation from a KrF excimer laser. Luminescence in the UV (204 nm), orange (570–640 nm) and IR (720–810 nm) regions, which is due to image–image, image–image and image–image transitions in image, respectively, has been observed from the image crystal at room temperature. No radiative transitions from the image image levels of image have been detected from the image crystal. It was assumed that at low temperatures the two- photon excitation of the image crystal with a KrF laser could result in the observation of short-wavelength upconverted VUV luminescence at image nm due to image–image transitions in image .