Vibrational properties and Raman spectra of pristine and fluorinated blue phosphorene.

Using density functional theory, we investigated the vibrational properties and Raman spectra of pristine blue phosphorene and fluorinated blue phosphorene. The fluorinated blue phosphorene possesses a Dirac cone at the K point (about 310 cm-1). The shape of the Dirac cone remains unchanged under different tensile strains. The Raman tensor and thus angle-dependent Raman intensities of all Raman active modes are calculated for the polarizations of scattered light parallel and perpendicular to that of the incident light. The characteristics of angle-dependent Raman intensities are discussed. Moreover, the polarization direction averaged non-resonant Raman spectra of pristine blue phosphorene and fluorinated blue phosphorene are compared with that of germanene and black phosphorene.