In situ imaging and spectroscopy of single-wall carbon nanotube synthesis by laser vaporization

The synthesis of single-wall carbon nanotubes by Nd:YAG laser vaporization of a graphite/(Ni, Co) target is investigated by laser-induced luminescence imaging and spectroscopy of Co atoms, C-2 and C-3 molecules, and clusters at 1000 degrees C in flowing 500 Torr Ar. These laser-induced emission imag es under typical synthesis conditions show that the plume of vaporized mate rial is segregated and confined within a vortex ring which maintains a simi lar to 1 cm(3) volume for several seconds. Using time-resolved spectroscopy and spectroscopic imaging, the time for conversion of atomic and molecular species to clusters was measured for both carbon (200 mu s) and cobalt (2 ms). This rapid conversion of carbon to nanoparticles, combined with transm ission electron microscopy analysis of the collected deposits, indicate tha t nanotube growth occurs over several seconds in a plume of mixed nanoparti cles. By adjusting the time spent by the plume within the high-temperature zone using these in situ diagnostics, single-walled nanotubes of controlled length were grown at an estimated rate of 0.2 mu m/s. (C) 2000 American In stitute of Physics. [S0003-6951(00)02102-1].