PHOTOACOUSTIC SPECTRA OF RARE-EARTH PENTAPHOSPHATES

The photoacoustic (PA) spectra of rare earth pentaphosphates of the general formula REP//5O//1//4, where RE equals Pr, Nd, Ho, Er, Tm, are reported. The photoacoustic bands were identified and compared with the absorption spectra. For quantitative analysis of PA bands of lanthanide(III) ions, the intensity ratio vector is introduced, characterizing the intensity distribution of f-f transitions. It was found that the relative intensities of photoacoustic bands are comparable with the intensities of absorption bands. It is concluded that the nonradiative relaxation mechanism leading to the PA signal is independent of the manifold-to-manifold J-J prime radiationless transitions.