Abstract
The phenomena of single wall carbon nanotubes (SWNTs) exposed to photoflash have been investigated and the corresponding response which is called photoacoustic effect was studied. In this work, five carbon materials includingas-synthesized SWNTs, purified SWNTs, multi-walled carbon nanotubes (MWNTs), carbon nanocapsules, and carbon fibers were photoflash-exposed and their results were compared. All the carbon materials except carbon fibers were synthesized through the floating catalyst chemical vapor deposition (CVD) method which used xylene as the carbon source and the ferrocene as the catalyst. The results showed that the raw SWNTs and the MWNTs were oxidized when they were exposed to photoflash. Increase in temperature of the carbon nanotubes (CNTs) over 475oC due to photoflash exposure was attained, which causes oxidation of both the CNTs and embedded iron catalysts in such a high temperature. Moreover, ignition occurred when the CNTs containing numerous carbon nanocapsules were photoflash-tested, and the residual products may contain Fe2O3 or Fe3O4 depending on the degree of ignition. However, no reaction occurs for the purified SWNTs and the carbon fiber. In this study, X-Ray, FE-SEM, and HRTEM were used to identify the composition of residual products and to study the variation in microstructures of the CNTs. The study reveals that ignition of the CNTs under photoflash exposure is significantly influenced by the amount of iron catalysts embedded in the CNTs