Zusammenfassung
In this work, we explain the origin and the mechanism responsible for
the strong enhancement of the Raman signal of sulfur chains encapsulated
by single-wall carbon nanotubes by running resonance Raman measurements
in a wide range of excitation energies for two nanotube samples with
different diameter distributions. The Raman signal associated with the
vibrational modes of the sulfur chain is observed when it is confined by
small-diameter metallic nanotubes. Moreover, a strong enhancement of the
Raman signal is observed for excitation energies corresponding to the
formation of excited nanotube-chain-hybrid electronic states. Our
hypothesis was further tested by high pressure Raman measurements and
confirmed by density functional theory calculations of the electronic
density of states of hybrid systems formed by sulfur chains encapsulated
by different types of single-wall carbon nanotubes.
Nutzer