THE UP-CONVERSION LUMINESCENCE PHENOMENON IN HoP_5O_(14) NONCRYSTALLINE
Chen Jinkai Chen Xiaobo(Experiment Center, Fujian Normal University, Fuzhou 350007)
In this paper an up-conversion luminescence phenomenon at room temperature in HoP5O14 noncrystalline induced by a pulsed DCM dye laser is reported. Several anti-stokes lines corresponding to 5G4(3G,5G)5, 5F3,5S2→5I8 and 5G4→5I7 transitions were observed. The dependence of the emission signal on the laser energy shows that all of them belong to a two-photon process. The excitation spectra for all of up-conversion emissions have a same peak possition as that of 5I8→5F5 absorption line and a very similar shape. Its value is equal to the square of this absorption shape. All of these indicate that they come from the same origin, the pump photons are absorpted by more than one ion, and energy transfer between ions via the interaction should be responsible for this up--conversion.Most likely, the homo-or hetero-excited pair of nearest neighbour Ho3+ ions, which result from the subsequent resonant energy transfer and nonradiative relaxation, exchange their energy to add to one .ion and bring about the population of above mentioned higher excited states. The time-resolved experiments further support our inference. Compaied to the fluorescence excited by 355nm laser, the anti-stokes line of (5G, 3H)5→5I8 dose not show up, but the relative intensity of 5F3→5I8 emission is about twice enhenced, which shows that among so many possible up-conversion channels this one seems to be the strongest.