Luminescence quantum efficiency determination in LiYF4:Nd3+ using photoacoustic spectroscopy

Optical properties of LiYF4:Nd3+ were studied using absorption, emission, excitation and photo acoustic spectroscopies. The Nd3+ transitions were identified and the Stark sublevels were determined for the 4I9/2, 4I11/2 and 4F3/2 levels. It is also presented and analysed three methods for the luminescence quantum efficiency determination, based on parameters from the spectra mentioned above. These methods were applied to four groups centered on 517, 577, 743 and 792nm. The first method provided values too high due to its assumption that the material has only one luminescent channel. The values obtained from the second one are still somewhat high but closer to the expected ones. The superestimation can be atributed to the imprecision in the existing branching ratios values, needed in this method. The third one, developed from the other two, provided values closer to the expected ones, but also affected by experimental conditions limitations, mainly related to the spectral resolution of the photoacustic spectra. The obtained results show that this method, once improved and associated to better experimental conditions, will lead to more accurate luminescence quantum efficiency values. (author)