Excitonic fine structure in emission of linear carbon chains

TL;DR

This study investigates the excitonic fine structure in linear carbon chains stabilized by gold nanoparticles, revealing characteristic triplet features, exciton dynamics, and temperature-dependent decay channels, with implications for nanoscale optoelectronic applications.

Contribution

It provides the first detailed analysis of excitonic fine structures and their temperature-dependent behavior in monoatomic linear carbon chains.

Findings

Observation of characteristic triplet fine-structures in PL spectra.

Identification of edge-state neutral excitons and charged trions.

Radiative lifetime increases with chain length and is about 1 ns.

Abstract

We studied monoatomic linear carbon chains stabilised by gold nanoparticles attached to their ends and deposited on a solid substrate. We observe spectral features of straight chains containing from 8 to 24 atoms. Low temperature PL spectra reveal characteristic triplet fine-structures that repeat themselves for carbon chains of different lengths. The triplet is invariably composed of a sharp intense peak accompanied by two broader satellites situated 15 and 40 meV below the main peak. We interpret these resonances as an edge-state neutral exciton, positively and negatively charged trions, respectively. The time-resolved PL shows that the radiative lifetime of the observed quasiparticles is about 1 ns, and it increases with the increase of the length of the chain. At high temperatures a non-radiative exciton decay channel appears due to the thermal hopping of carriers between parallel carbon chains. Excitons in carbon chains possess large oscillator strengths and extremely low inhomogeneous broadenings.