Low Temperature Spectral Properties of Several Pr~(3+) Doped Borates under VUV Excitation

Low temperature spectra of SrB4O7:Pr3+, LaBaO6:Pr3+ and LaMgB5O10:Pr3+ were investigated by synchrotron radiation VUV light. Under VUV excitation, photon cascade emission was found in SrB4O7:Pr3+, LaB3O6:Pr3+ and LaMgB5O10:Pr3+. All peaks in emission spectra were assigned. Because high phonon energy in borates results in non-radiative relaxation between 3P0 and 1D2 states of Pr3+, the second step emission 3Po→3HJ is very low in SrB4O7:Pr3+ and even is absent in LaB3O6:Pr3+ and LaMgBsO10:Pr3+. In the excitation spectra of LaBaO6:Pr3+ and LaMgB5O10:Pr3+, along with the 4f5d absorption bands, a weak line due to 3H4→1S0 transition also was detected. Prom the position of 3 H4→1S0 transition, the energy difference of 1So state and the lowest 4f5d state was determined.