Laser irradiation of carbon nanotube films: Effects and heat dissipation probed by Raman spectroscopy

Abstract

We investigate the thermal properties of thin films formed by single- and multi-walled carbon nanotubes submitted to laser irradiation using Raman scattering as a probe of both the tube morphology and the local temperature. The nanotubes were submitted to heating/cooling cycles attaining high laser intensities (∼1.4 MW/cm2) under vacuum and in the presence of an atmosphere, with and without oxygen. We investigate the heat diffusion of the irradiated nanotubes to their surroundings and the effect of laser annealing on their properties. The presence of oxygen during laser irradiation gives rise to an irreversible increase of the Raman efficiency of the carbon nanotubes and to a remarkable increase of the thermal conductivity of multi-walled films. The second effect can be applied to design thermal conductive channels in devices based on carbon nanotube films using laser beams.

Photonic Sorting of Aligned, Crystalline Carbon Nanotube Textiles

“…In literature, the most successful CNT laser treatments involved illuminating unaligned SWCNTs in air supported by a substrate, where often the treating laser was also used to probe for Raman spectroscopy 9 , 11 – 13 , 37 – 39 . With laser illumination lasting tens of seconds to hours, the general outcome was modification of the Raman radial breathing modes from preferential oxidation of small diameter SWCNTs 11 or metallic SWCNTs 9 , 12 , 13 .…”

In situ tracking of defect healing and purification of single-wall carbon nanotubes with laser radiation by time-resolved Raman spectroscopy

“…On the one hand, based on the limited literature, several noteworthy studies infer a promising ability to purify and heal defects in pristine (as-produced) or pretreated (annealed or oxidised) CNT samples with the help of different lasers. On the other hand, others report the lack of any positive effect, [25][26][27][28] or selective removal of metallic or semiconducting tubes. [29][30][31] However, in the literature, CNT purication and healing with laser has been limited in scope and data volume.…”

Skin effect mitigation in laser processed multi-walled carbon nanotube/copper conductors

“…I D /I G reflects the ratio of structural defects and degree of disorder in the graphitic walls of nanotubes. 24 As the irradiated power density increases, the I D /I G ratio decreases from 1.01 to 0.86, indicating the reduction of dangling bonds and improvement of crystallinity in graphitic shells of the MWCNTs. Moreover, the FWHM of the D-band decreases as the laser power density increases, indicating improved structural integrity and reduced impurities in the MWCNT coatings.…”