Raman spectroscopy of RFeAsO (R=Sm, La)

We report the polarized Raman spectra of undoped RFeAsO (R=Sm, La) collected at room temperature from ab surfaces of impurity-free microcrystals. The spectra exhibit sharp phonon lines on very weak electronic scattering background. The frequency and symmetry of the four Raman phonons involving out-of-plane atomic vibrations are found at 170 cm(-1) (A(1g), Sm), 201 cm(-1) (A(1g), As), 208 cm(-1) (B(1g), Fe), and 345 cm(-1) (B(1g), O) for SmFeAsO; and 162 cm(-1) (A(1g), La), 208 cm(-1) (A(1g), As), 201 cm(-1) (B(1g), Fe), and 316 cm(-1) (B(1g), O) for LaFeAsO.