Photoluminescence from single walled carbon nanotubes: a comparison between suspended and micelle-encapsulated nanotubes

TL;DR

This study compares photoluminescence from suspended and micelle-encapsulated single-walled carbon nanotubes, revealing consistent blue-shifts in emission and absorption peaks for suspended nanotubes, with minimal dependence on chirality or diameter.

Contribution

It provides a direct comparison of PL properties between suspended and encapsulated SWNTs, highlighting systematic spectral shifts and their weak dependence on nanotube characteristics.

Findings

Suspended SWNTs show a 28 meV blue-shift in emission peaks.

Absorption peaks are blue-shifted by 16 meV in suspended SWNTs.

Shifts are weakly dependent on chirality and diameter.

Abstract

Single walled carbon nanotubes (SWNTs) are luminescent. Up to now, two preparation methods, both of which isolate individual SWNTs, have enabled the detection of nanotube bandgap photoluminescence (PL): encapsulation of individual SWNTs into surfactant micelles, and direct growth of individual SWNTs suspended in air between pillars. This paper compares the PL obtained from suspended SWNTs to published PL data obtained from encapsulated SWNTs. We find that emission peaks are blue-shifted by 28 meV on average for the suspended nanotubes as compared to the encapsulated nanotubes. Similarly, the resonant absorption peaks are blue-shifted on average by 16 meV. Both shifts depend weakly on the particular chirality and diameter of the SWNT.