Probing the chemical role of ambient O2 in the formation of carbon nanotubes via excimer laser ablation

G. Radhakrishnan; P. M. Adams; L. S. Bernstein

doi:10.1117/12.705260

13 March 2007 Probing the chemical role of ambient O₂ in the formation of carbon nanotubes via excimer laser ablation

G. Radhakrishnan, P. M. Adams, L. S. Bernstein

Proceedings Volume 6458, Photon Processing in Microelectronics and Photonics VI; 64581I (2007) https://doi.org/10.1117/12.705260
Event: Lasers and Applications in Science and Engineering, 2007, San Jose, California, United States

Abstract

Room-temperature ablation of a composite graphite-metal target, at 248 nm, in O₂, produces large-channeled (50 - 150 nm) multiwalled carbon nanotubes. We find that the formation of these carbon nanotubes is dependent on the ambient gas employed during ablation. Such structures are not produced in inert atmospheres of Ar or in high vacuum. High-resolution, in-situ, time-resolved emission spectroscopy has been used to track the evolution of species (C₂, C₃, Ni/Co) in the ablation plume, in different ambient gas atmospheres. Spectral fits on low and high-resolution spectra reveal time-dependent vibrational-rotational temperatures for C₂ that are different in O₂ compared to Ar. Spectral modeling shows that the vibrational-rotational temperatures for C₂ produced in O₂ remain at ~ 5000 K for nearly 20 &mgr;sec, but drop rapidly in Ar. The key role of exothermic reactions occurring in the plume, and that of radiative cooling will be discussed.

Citation Download Citation

G. Radhakrishnan, P. M. Adams, and L. S. Bernstein "Probing the chemical role of ambient O₂ in the formation of carbon nanotubes via excimer laser ablation", Proc. SPIE 6458, Photon Processing in Microelectronics and Photonics VI, 64581I (13 March 2007); https://doi.org/10.1117/12.705260

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