Effect of Water Filling on the Electronic and Vibrational Resonances of Carbon Nanotubes: Characterizing Tube Opening by Raman Spectroscopy

Abstract

Water accessibility of single wall carbon nanotubes (SWCNTs) can be monitored by resonant Raman spectroscopy (RRS) (see figure and cover) of the radial breathing modes of bile salt‐solubilized CNTs. The RRS features of empty and water‐filled CNTs can be very well resolved, and vibrational and electronic shifts and broadenings have been accurately determined. The results also lead to a simple ratiometric method to quantify tube opening under various chemical and mechanical treatments.

Sonication-assisted dispersion of carbon nanotubes in aqueous solutions of the anionic surfactant SDBS: The role of sonication energy

“…The stronger steric repulsion between tubes that is generated by the increased amounts of functional groups was also suggested to be responsible for this promotion effect [21]. However, the former interpretation [34] may be unreasonable, because the plateau A HD values (~130 nm) of the three SWCNTs were almost the same (Figure 4). If the functionalized SWCNTs are more easily cut by sonication [34], the plateau A HD value for the SWCNTs with more functional groups should be smaller.…”

“…However, the former interpretation [34] may be unreasonable, because the plateau A HD values (~130 nm) of the three SWCNTs were almost the same (Figure 4). If the functionalized SWCNTs are more easily cut by sonication [34], the plateau A HD value for the SWCNTs with more functional groups should be smaller. More evidence was provided by the fact that the shorter, cut SWCNTs showed lower dispersed concentrations (Figure 5(a)), but this phenomenon was not observed for the functionalized H-SWCNTs and C-SWCNTs in Figure 4.…”

“…For example, at a supplied sonication energy of 500 J/mL, the dispersed concentration of the three SWCNT types followed the order of C-SWCNTs > HSWCNTs > P-SWCNTs (Figure 4), which corresponded to the amounts of attached functional groups (Table 2). This promotion effect on the CNT dispersions can be attributed to the defects on the CNT sidewalls or at the ends of sidewalls, which are generated by surface oxidation [21]; the presence of these defects means that the functionalized SWCNTs can be cut more easily using sonication [34]. The stronger steric repulsion between tubes that is generated by the increased amounts of functional groups was also suggested to be responsible for this promotion effect [21].…”

“…This result indicated that the dispersed concentration depended on the supplied sonication energy, but not the sonication time or the output power of sonicator alone. The fact that the sonication energy determined the dispersion of CNTs can probably be attributed to the mechanical energy provided by the sonicator overcoming the attractive vdW forces between the CNT aggregates, leading to their disentanglement and dispersion [11,34]. Another possible mechanism is the generation of cavitation bubbles in the sonication process [35][36][37].…”

Quasiphase Transition in a Single File of Water Molecules Encapsulated in (6,5) Carbon Nanotubes Observed by Temperature-Dependent Photoluminescence Spectroscopy

“…[11,12] Additionally, they combine atomically-precise diameters matching the size of various molecules with a onedimensional character and possess structure-dependent optical properties that are extremely sensitive to the presence of encapsulated molecules, leading to characteristic spectral shifts. [13][14][15][16][17]. In this work, we therefore exploit these optical transitions as ultrasenstive probes for the temperature-dependent behavior of a single file of water molecules encapsulated inside (6,5) SWCNTs.…”