Probing carbon isotope effects on the Raman spectra of graphene with different [superscript 13]C concentrations

Citation Carvalho, Bruno R., et al. "Probing carbon isotope effects on the Raman spectra of graphene with different [superscript 13]C concentrations. Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. A resonance Raman study of graphene samples with different 13 C isotopic concentrations and using different laser excitation energies is presented. The main Raman peaks (D, G, G * , and 2D) of graphene were measured and the dependence of their frequencies on the isotope atomic mass follows a simple harmonic oscillator relation. The G * and 2D double-resonance peak positions were measured as a function of the laser energy, and we observed that the slopes of the laser energy dependence are the same independently of isotope concentration. This result shows that isotopic substitution does not alter the electron and phonon dispersions near the K point of the graphene Brillouin zone. From the linewidth of G and 2D Raman peaks, we have also obtained a dependence of the phonon lifetime on the 13 C isotope concentration.