UC Berkeley

We investigate the N = 9 atoms wide armchair-type graphene nanoribbons (9-AGNRs) by performing a comprehensive spectroscopic and microscopic characterization of this novel material. In particular, we use X-ray photoelectron, near edge X-ray absorption fine structure, scanning tunneling, polarized Raman and angle-resolved photoemission (ARPES) spectroscopies. The ARPES measurements are aided by calculations of the photoemission matrix elements which yield the position in k space having the strongest photoemission cross section. Comparison with well-studied narrow N = 7 AGNRs shows that the effective electron mass in 9-AGNRs is reduced by two times and the valence band maximum is shifted to lower binding energy by ∼0.6 eV. In polarized Raman measurements of the aligned 9-AGNR, we reveal anisotropic signal depending upon the phonon symmetry. Our results indicate the 9-AGNRs are a novel 1D semiconductor with a high potential in nanoelectronic applications.