Anti-Stokes Yb3+ emission—Valuable structure information in spectra of rare earth compounds measured with FT-Raman spectrometers

Raman spectroscopy is a powerful and simple method which proved to be very useful in studies of solids. The most widely used Raman spectrometers are FT-Raman instruments with YAG:Nd3+ laser as an excitation source. However, in the case of samples containing rare earth elements, the quality of FT-Raman spectra is often low due to strong fluorescence effects. We show that, in such cases, anti-Stokes part of the Raman spectra often contains strong, well resolved bands identified as multiphonon-assisted emission bands of Yb3+ present as an impurity. We show on several examples that analysis of these bands may provide useful structure information, similar to that obtained by “Eu structure probe” method in optical spectroscopy. The Yb3+ emission can be also measured using standard luminescence detection systems. However, the application of FT-Raman system allows one to obtain good quality spectra in a much cheaper, easier and faster way (in times as short as a few seconds). Moreover, high-sensitivity of FT-Raman spectrometers allows to detect even very small amounts of Yb3+ impurity.