Investigating the Absorption Properties of Pure and Nitrogen-Doped Carbon Clusters as Models for the Core of Carbon Nanodots

The study of amorphous carbon structures of different sizes and extensions is relevant to many research areas, including electrode processes (e.g., intercalation), astrochemistry, catalysis, and sensors. While the structure of amorphous carbon structures has been investigated thoroughly in the past, a systematic analysis of their properties upon doping with functional groups is far less extensive. This aspect is particularly important for carbon nanodots (CNDs), a photoluminescent species of carbon-based nanoparticles whose optical properties arise from the interplay between core electronic structure, surface states, heteroatom doping, and molecular fluorophores. Despite extensive experimental work, an atomistic rationalization of their optical properties is still not available. In this study, we adopt a bottom-up computational approach using amorphous pure carbon clusters (C₁₀-C₆₀) and nitrogen-substituted ones (C₉N-C₅₉N) as models for the unsaturated and partially doped domains of CND cores. Structural isomers were generated along with computed UV/vis spectra to rationalize the property changes upon nitrogen substitution.