Er^3- / Yb^3＋ co - doped silica - alumina monolithic xerogels were prepared with the same concentration on 2 000 Er/Si ppm and 6 000 AI/Si ppm. The Yb/Si content was varied from 0 to 4 000 ppm. Densification of the s...Er^3- / Yb^3＋ co - doped silica - alumina monolithic xerogels were prepared with the same concentration on 2 000 Er/Si ppm and 6 000 AI/Si ppm. The Yb/Si content was varied from 0 to 4 000 ppm. Densification of the samples was achieved by thermal treatment in air at 950 ~C for 120 hours with a heating rate 0.1 ~C / min. Photoluminescence spectroscopy was used to obtain information about the effective excitation efficiency of Er^3＋ ions by co-doping with Yb^3- ions. The infrared-to-visible up-conversion luminescence has been investigated upon continuous wave excitation at 980 nm. The samples exhibit red, green and blue upconversion emission. It is found that the intensity of up-conversion luminescence increases with increasing Yb3- doping concentration. An opposite behavior is observed for the 4 I13/2 luminescence of the Er^3＋ ions.展开更多
This contribution reports on application of low-wavenumber Raman scattering on acoustical vibrational modes of nanoparticles.Theoretical background as well as the experimental results in determination of oxide and sem...This contribution reports on application of low-wavenumber Raman scattering on acoustical vibrational modes of nanoparticles.Theoretical background as well as the experimental results in determination of oxide and semiconductor particle size distribution will be presented.展开更多
基金This research is performed in the context of the Italy-Vietnamre-search project 6 BS 2 MAE2006-2008 .MIUR-FIRB RBNE012N3X,PAT FAPVU2004-2006 ,MIUR-PRIN2004-2006 .
文摘Er^3- / Yb^3＋ co - doped silica - alumina monolithic xerogels were prepared with the same concentration on 2 000 Er/Si ppm and 6 000 AI/Si ppm. The Yb/Si content was varied from 0 to 4 000 ppm. Densification of the samples was achieved by thermal treatment in air at 950 ~C for 120 hours with a heating rate 0.1 ~C / min. Photoluminescence spectroscopy was used to obtain information about the effective excitation efficiency of Er^3＋ ions by co-doping with Yb^3- ions. The infrared-to-visible up-conversion luminescence has been investigated upon continuous wave excitation at 980 nm. The samples exhibit red, green and blue upconversion emission. It is found that the intensity of up-conversion luminescence increases with increasing Yb3- doping concentration. An opposite behavior is observed for the 4 I13/2 luminescence of the Er^3＋ ions.
文摘This contribution reports on application of low-wavenumber Raman scattering on acoustical vibrational modes of nanoparticles.Theoretical background as well as the experimental results in determination of oxide and semiconductor particle size distribution will be presented.
