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In order to improve the understanding of laser interactions of materials with homogeneous nano-structures, pulsed laser induced plasma from a low density, high-porosity multiwall carbon nanotube (CNT) sponge and a dense graphite block have been investigated by combinational spectroscopy approaches. We observe distinct differences in the laser-induced light emission of the CNT sponge and graphite block which we attribute to the occurrence of a phase explosion caused by the lower thermal conductivity and weaker mechanical strength of the CNT sponge. Furthermore, spectroscopy plasma analysis reveals that differences in the surface of the two systems play a key role in the generation of negative carbon ions. We observe a more effective production of negative ions for the CNT sponge as compared to the graphite block due to the greater number of surface defects of the CNT sponge. [ABSTRACT FROM AUTHOR]

The anisotropy in thermoelectric properties of three-dimensional carbon nanotubes (CNTs) and CNT/polyaniline (PANI) composites have been studied by utilizing an orderly aligned CNT arrays with a self-sustained construction. In the length direction of CNT, the electrical conductivity of the CNT array is ∼5 times larger as compared to the direction vertical to the alignment of CNTs, while the difference in thermal conductivity between these two directions is ∼25 times. As a result, strong anisotropic thermoelectric transportation has been also observed in the composites composed of PANI and CNT arrays. An enhanced thermopower in the composites, as compared to the pure PANI or CNTs, is only observed in the direction along the CNTs. This study helps the fundamental understanding on the un-conventional improved thermopower, which is more likely to be realized via adjusting the carrier transportation within the interface between CNTs and PANI rather than across it. [ABSTRACT FROM AUTHOR]