Multivariate curve resolution for angle-resolved polarized Raman spectroscopy of ferroelectric crystals

Abstract

Raman spectra from crystals contain a mixture of peaks from various phonon modes. Angle-resolved polarized Raman spectroscopy, in which numerous spectra are obtained with different polarization angles of incident and scattered lights, is widely used to separate peaks by considering the symmetries of the Raman tensor. In the present study, to efficiently process large amounts of spectral data, we apply multivariate curve resolution (MCR) to Raman spectra from a typical ferroelectric PbTiO3 crystal to reduce the number of spectra to be fitted. The spectra to fit are thus reduced to three, and their fits determine all the phonon parameters, such as frequency shift, width, and integrated intensity. The angle dependence of the integrated intensity was determined by multiplying the integrated intensity of the three peaks by the angle profiles obtained by MCR. Thus, angle-resolved polarized Raman spectroscopy combined with MCR provides an efficient way to determine phonon parameters.