Spectra and energy levels of trivalent samarium in strontium fluorapatite

Absorption and fluorescence spectra are reported for Sm3+(4f(5)) as a dopan t in crystals of strontium fluorapatite, Sr-5(PO4)(3)F. Spectra were obtain ed at sample temperatures near 10, 100 K, and room temperature. The absorpt ion spectra covered the wavelength range between 2840 and 520 nm and were a nalyzed for the detailed crystal-field splitting of the H-6(J), F-6(J), (4) G(4)(5/2), and F-4(3)(3/2) multiplet manifolds of Sm3+(4f(5)). Fluorescence spectra were observed from the (4)G(4)(5/2) to the H-6(5/2) (ground state) , H-6(7/2), H-6(9/2), and part of the H-6(11/2) manifolds. The strongest fl uorescence is observed to the H-6(9/2) manifold. The distribution of the fl uorescence intensities is similar to that observed for the Sm3+-doped glass laser. A detailed crystal-field splitting calculation was carried out for the 14 multiplet manifolds of Sm3+ that are lowest in energy. A rms deviati on of 8 cm(-1) was obtained between 49 experimental and calculated energy S tark levels. The calculation also predicts fluorescence branching ratios an d the (4)G(4)(5/2) radiative lifetime, in reasonable agreement with our mea sured values. (C) 1999 American Institute of Physics. [S0021-8979(99)10120- 8].