Single-Chirality Separation and Optical Properties of (5,4) Single-Wall Carbon Nanotubes

Abstract

In this study, high-purity single-chirality (5,4) and (6,4) single-wall carbon nanotubes (SWCNTs) were efficiently extracted using gel chromatography, and their optical properties were investigated. In the photoluminescence spectrum, the (5,4) SWCNTs exhibited multiple emission peaks, such as E11 * at 968 and E11 *− at 1096 nm, in addition to the original E11 peak at 829 nm for the E22 excitation. Although the (6,4) SWCNTs also exhibited similar emission peaks, the intensity of the additional peaks relative to the E11 peak was approximately four times lower than that of (5,4) SWCNTs, even though the same separation procedure was used for both species. The results from density functional theory calculations indicated that both the E11 * and E11 *− emissions originated as emissions from the oxide states. Because no oxidation treatments were performed on the samples, these oxides were most likely spontaneously produced during the sample preparation process. Theoretical results indicated that the (5,4) SWCNT possesses a more stable ether-a-O structure that could cause the E11 * emission. The difference in the stability of the oxide states for (5,4) SWCNT and (6,4) SWCNT strongly suggests that the (5,4) SWCNT is more likely to be oxidized by weak stimulation. These results indicate that the (5,4) SWCNT remained near the outside of the robust structure due to its strong curvature effects.

Emergence of new red-shifted carbon nanotube photoluminescence based on proximal doped-site design

“…Very recently, Wei et al . have reported that the naturally-oxidized (5,4)SWNTs showed a small PL peak at 1096 nm which is lower energy emission than E 11 (829 nm) and E 11 * (968 nm) and suggested that the observed emission may be due to epoxy structure formation at the oxygen-doped sites 22 . The result also indicates that the doped-chemical structures on the SWNTs dominate the resulting emission properties.…”

Stereochemistry of Simple Molecules inside Nanotubes and Fullerenes: Unusual Behavior of Usual Systems

“…A different chirality suggests that such objects create the individual enantiomeric pairs, also denoted as P and M nanotubes with a single set of values (n,m) [251]. Depending on the ratio between chirality indexes, they display features of conductors or semiconductors [252] and have valuable optical properties [253]. It was shown that the doping of chiral nanotubes with nitrogen diminishes the stress caused by the small diameter and the corresponding energy strongly depends on the tube helicity [254].…”

Sonochemical reaction to control the near-infrared photoluminescence properties of single-walled carbon nanotubes

“…32 Kataura and co-workers reported that the treatment of SWNTs with hydrogen peroxide caused the oxidation of small-diameter (5,4)SWNTs, leading to the emergence of a red-shifted PL peak. 33 Based on these reported studies, OH˙, H2O2, and radical species generated from SDBS via hydrogen abstraction are considered as plausible reactive species that generate quantum defects on the SWNTs upon ultrasonic irradiation. In addition, it has been reported that the decomposition rate of organic compounds by sonication increased under Ar atmosphere than under oxygen or ambient atmosphere.…”