Laser‐induced damage and destruction of HiPCO nanotubes in different gas environments

Abstract

1074, Web: www.ltu.seWe have studied the thermal and chemical stability of HiPCOproduced single-walled carbon nanotube bundles to high laser power in air and argon. The samples were exposed to 110 kW/ cm 2 during 8 h with a 1.96 eV laser and the temperature was monitored via downshift of G þ -Raman peak. The structural changes in the carbon nanotubes (CNTs) caused by laser heating were monitored by recording their Raman spectra at ambient T (reference conditions) to ensure unaltered resonance conditions. The initial temperature was estimated to be 550 8C and 870 8C in air and argon, respectively. The Raman signal intensity from the CNTs radial breathing mode (RBM) increased rapidly at the beginning of the laser heating both under air and argon due to desorption of impurities for all but the smallest diameter CNTs. The temperature dropped by 30% under argon and 60% under air due to destruction of the absorbers -CNTs in resonance with incident radiation. The final RBM spectra exhibited intensity loss only for the smallest diameter CNTs in argon atmosphere and for all but the largest diameter CNTs in air. Our results demonstrate the importance of (i) impurity desorption from exterior and interior of CNTs; (ii) different temperature thresholds for the CNT destruction due to oxidation and overheating; (iii) the role of photon absorbers on the thermal stability of the sample. The small diameter CNTs are more easily destroyed than large diameter ones. The metallic nanotubes also tend to have lower thermal stability.

Wavelength-dependent photoconductivity of single-walled carbon nanotube layers

“…52 In comparison, the shi of peaks was observed with laser powers at least 5 times higher. 53,54 The thermal inuence on the optical absorption spectra of SWCNT layers was also studied in situ. The absorbance measured for a different sample (see ESI, Fig.…”

Laser Lithography of a Tube-in-a-Tube Nanostructure

“… , Even upon defunctionalization, which provides a second G outer contribution at high wavenumbers, the left shoulder peak corresponding to the G inner shifts to lower wavenumbers in correlation to higher laser power densities. Furthermore, it has been shown that a high power density laser, such as that used here, is capable of heating CNTs to 300–800 °C. , Additionally, the annealing exhibited a strong dependence on the Tube^2 film thickness. We found that for a thicker film, a lower power density was required to induce laser writing (Figure S6).…”

Laser-induced nanostructuration of vertically aligned carbon nanotubes coated with nickel oxide nanoparticles

“…The presence of much smaller NiO No significant flaws are observed in the inner part of the CNTs. Previous works report the formation of different types of damage in CNT submitted to laser irradiation [47,48]. Furthermore, profuse laser-induced effects can lead to complex structural modifications such as unzipping of CNT to graphene nanoribbons, and even their transformation to polymers [49,50].…”