Spectral characterization and excited-state interactions between rare earth ions doped in borosilicate and sol-gel glasses: energy transfer up-conversion in the Pr-Sm system

摘要

Spectroscopic properties of selected 4f-elements in a sol-gel and two high temperature silicate based glasses are reported. In particular, the spectral properties of the Eu~3+ ion have been used to probe the local coordination environment of the f-elements in these glass matrices. Luminescence studies of the high temperature glasses indicated that the electric dipole allowed f-f transitions dominate the spectra which suggests that the local symmetry around the 4f-ions is low. Temperature-dependent spectroscopic studies of the sol-gel glasses indicated that the the f-elements retain a "solution-like" environment prior to thermal processing. After heat treatment, an increase in the emission intensities of the electric-dipole transitions is accompanied by a concomitant decrease in the magnetic-dipole allowedtransitions. moreover, excited state interactions has also been observed in the high temperature glasses that contain certain multiple f-elements. In Pr-Sm systems, exclusive excitation of the sm~3+ ion with a 514 nm argon ion laser line provides a higher energy emission band (ca. 490 nm) from the Pr~3+ ion (~3P_0 -> ~3H_4) transition. This energy up-conversion is attributed to energy transfer from the ~6H_13/2 level of the Sm~3= ion to the ~3H-6 state of the Pr~3+ ion. Following a second photon absorption. the Pr~3+ ion is excited to the emitting ~3P_0 level.