Ultraviolet and near-infrared Raman spectroscopy of graphitic C3N4 phase

Here, we report measurements of the Raman spectra of graphitic g-C3N4 phase, using deep ultraviolet (UV, 244 nm) and near-infrared (NIR, 785 nm) light for excitation of Raman scattering. It is demonstrated that the UV and NIR Raman spectra of g-C3N4 phases are substantially different from those measured with visible Raman spectroscopy. A typical Raman spectrum of the g-C3N4 phase obtained with visible Raman spectroscopy shows two main overlapping bands at 1357 and 1560 cm−1. In contrast, UV and NIR Raman spectra of g-C3N4 phase exhibit two strong peaks around 691 and 988 cm−1. These peaks are tentatively assigned to different types of the s-triazine ring breathing modes. Strong and distinguished features of the UV and NIR Raman spectra of g-C3N4 phases should provide a valuable 'fingerprint' for Raman spectroscopy studies of phase transition of these phases under high pressure and high temperatures.