【摘要】 文章采用双光栅单色仪(HRD-1),氩离子激光器的488.0 nm波长激发,分别测得室温下,激发光平行、垂直晶体c轴入射时,Tm3+,Ho3+单掺和双掺钒酸钇晶体的拉曼光谱,对检测结果进行分析并探讨了对能量转移的影响。观测到对Ho3+∶YVO4,激发光垂直c轴时的散射光强明显强于激发光平行c轴时的散射光强;由于488.0 nm波长靠近Ho3+的一个吸收峰,吸收和散射相互竞争,使475 cm-1被削弱,且外模振动展宽;测得样品最大声子能量集中在880 cm-1附近。主要是(VO4)3-的A1g呼吸模引起的,表明与YAG基质一样,也是一种具有高声子能量的晶体。用808 nm激发,锁相放大器,PbS探头接收,测得双掺Tm3+∶Ho3+∶YVO4的2.09μm荧光强度是单掺Tm3+∶YVO41.85μm的4/5,意味着Tm3+对Ho3+的敏化效率高达80%,因为Tm3+∶YVO4的荧光谱与Ho3+吸收谱重合甚少,由辐射跃迁导致的能量转移可能性不大,因此Tm3+离子之间的交叉弛豫以及Tm3+的3F4与Ho3+的5I7之间近共振的能量转移主要是依靠声子辅助的无辐射跃迁。更多还原

【Abstract】 Raman spectra of Tm3+∶YVO4,Ho3+∶YVO4 and Tm3+∶Ho3+∶YVO4 crystals were measured at room temperature by HRD-1 double grating monochromator,with the excitation laser beam were parallel and perpendicular to c axis,respectively.For the Ho3+∶YVO4,it was found that the Raman spectrum excited by laser beam perpendicular to axis c is stronger than that by parallel excitation,and because 488 nm laser was very close to the absorption peak of Ho3+,the competition between absorption and scattering results in the 475 cm-1 Raman mode weakening and external mode widening. It was also found that the most probable phonon energy focused on the 880 cm-1,which was brought about by the breathe mode of(VO4)3-.Like YAG,YVO4 is a kind of crystal with high phonon energy too.Comparing the luminescence of Tm3+∶YVO4 with that of Tm3+∶Ho3+∶YVO4, it was found that the intensity of Ho3+ 2.09 μm is about 4/5 of that of Tm3+ 1.85 μm,which means the sensitization efficiency of Tm3+ to Ho3+ was as high as up to 80%,and since the overlap between the luminescence of Tm3+ with the absorption of Ho3+ is quite small,the radiative energy transfer between them was very less possible,and most probability,this process was via the nonradiative,phonon-aided cross-relaxation between Tm3+ and near resonance energy transfer between Tm3+ and Ho3+.更多还原