Upconversion mechanisms in KPb_2Cl_5:Er~(3+) crystal

摘要

In this work we report infrared to visible upconversion luminescence in the low phonon-energy host material KPb_2Cl_5 doped with Er~(3+) ions. The low phonon energy strongly reduces multiphonon relaxation in this host. As a consequence, in addition to the strong green upconversion luminescence from ~2H_(11/2),~4S_(3/2)) levels at room temperature, blue luminescence from ~2H_(9/2) and ~4F_(7/2) levels is also observed under near infrared excitation in the ~4I_(9/2) (801 nm) and ~4I_(11/2) (978 nm) multiplets respectively. The upconversion mechanisms are investigated by means of excitation and timeresolved luminescence spectroscopy.