Investigating structural disparities in carbon nanoribbons and nanobelts through spectroscopies

In this study, simulated X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were utilized to differentiate the carbon nanoribbons (CNRs) and carbon nanobelts (CNBs) with different edges. CNRs, characterized by linear, extended π-conjugated systems, and CNBs, featuring closed-loop, cyclic structures, exhibit distinct bandgaps influenced by edge configuration and molecular structure. CNBs generally possess smaller bandgaps than GNRs due to enhanced π-conjugation and electron delocalization in their curved structures. Specifically, the bandgaps of zigzag-edged GNRs and CNBs are smaller than those of their armchair-edged counterparts. These differences in electronic states cause shifts in the position of the C1s XPS peaks. ANR and ANB exhibit lower binding energies (BEs) compared to ZNR and ZNB. The peak position differences, which are 1.3 eV between ZNR and ANR and 0.5 eV between ZNB and ANB, highlight how edge configuration can differentiate structures within the same ribbon or belt type. While ZNR and ZNB have nearly identical peak positions, rendering them hard to distinguish, the 0.9 eV difference between ANR and ANB allows for clear differentiation. In ZNR and ZNB, strong bands from C–H bending and C–C stretching were observed, with slight differences in band positions allowing for structural differentiation. In ANR and ANB, the Kekulé vibration band was most intense, appearing at lower wavenumbers in ANB. Additionally, ANB showed unique C–C stretching bands at 1483 and 1581 cm⁻¹, which were barely observed in ANR. This study lays the groundwork for future spectroscopic analysis of GNRs and CNBs.