Zigzag HgTe Nanowires Modify the Electron–Phonon Interaction in Chirality-Refined Single-Walled Carbon Nanotubes

Abstract

Atomically thin nanowires (NWs) can be synthesized inside single-walled carbon nanotubes (SWCNTs) and feature unique crystal structures. Here we show that HgTe nanowires formed inside small-diameter (<1 nm) SWCNTs can advantageously alter the optical and electronic properties of the SWCNTs. Metallic purification of the filled SWCNTs was achieved by a gel column chromatography method, leading to an efficient extraction of the semiconducting and metallic portions with known chiralities. Electron microscopic imaging revealed that zigzag HgTe chains were the dominant NW geometry in both the semiconducting and metallic species. Equilibrium-state and ultrafast spectroscopy demonstrated that the coupled electron–phonon system was modified by the encapsulated HgTe NWs, in a way that varied with the chirality. For semiconducting SWCNTs with HgTe NWs, Auger relaxation processes were suppressed, leading to enhanced photoluminescence emission. In contrast, HgTe NWs enhanced the Auger relaxation rate of metallic SWCNTs and created faster phonon relaxation, providing experimental evidence that encapsulated atomic chains can suppress hot carrier effects and therefore boost electronic transport.

Synthesis of manganese molybdate/MWCNT nanostructure composite with a simple approach for supercapacitor applications

“…It is known that the D band is related to crystal defects and disordered structure in carbon lattice, and the G band is attributed to the carbon atoms with sp 2 hybridization. 35 The I D / I G ratio reveals the degree of structural disorder in the composite powder. This ratio was calculated at about 1.14, suggesting defects of carbon structure in the MMO/C.…”

Spectroscopic Insights into the Influence of Filling Carbon Nanotubes with Atomic Nanowires for Photophysical and Photochemical Applications

“…The conductivity for both unfilled and HgTe-filled SWCNT films increased toward higher frequencies. Previous results, obtained in the mid-infrared using Fourier transform infrared (FTIR) spectroscopy on similar films placed on Si substrates, indicated the presence of a strong plasmon mode around 7–9 THz for the unfilled and filled samples . Here, additional conductivity in the spectrum of the HgTe-filled SWCNT film can be seen in the 0.5–2.0 THz range.…”

“…In previous studies, it was reported that infiltration of the CNTs by molecules can expand or distort the nanotube circumference, hence shifting the interband transition energy due to increased radial strain. ,, The energy shift with radial strain σ varies with chiral angle θ according to normalΔ E i i = false( prefix− 1 false) i + 1 false( prefix− 1 false) k + 1 3 t 0 σ .25em sin nobreak0em.25em⁡ 3 θ This relationship predicts a strong family-type dependence of the energy shift. In our previous work on solution-state HgTe-infiltrated SWCNTs, a dependence of filling-induced Δ E ii on k was seen for solution-state SWCNTs, with a generally larger Δ E ii for type 1 SWCNTs such as (7,5) and (10,2) than on type 2 SWCNTs such as (8,4) and (6,5). However, no such effect can be seen in the gelatin-embedded samples (Figure c), suggesting that the morphology (gelatin matrix) may prevent or offset substantial radial strain.…”

“…Pulsed excitation injects energy into the electronic system, which rapidly transfers to the lattice via electron–phonon coupling. This can occur rapidly via Auger processes in HgTe-filled SWCNTs, as we previously reported . Here, however, we suggest that the family-dependent shifts in the excitonic energies seen in the experiment may be linked to modified uniaxial or radial strain coefficients in line with eqs and .…”

“…Processes of SWCNT filling and purification based on the gel column chromatography method were detailed in our previous work . The extracted semiconducting SWCNTs with a dominance of small nanotubes ( d t < 1 nm) were chosen for the study here.…”