Selective Production of Single-Wall Carbon Nanohorn Aggregates and Their Formation Mechanism

Single-wall carbon nanohorn (SWNH) aggregates can be produced by CO2 laser vaporization of carbon, and a single aggregate can take either a “dahlia-like” or “bud-like” form. We found that “dahlia-like” SWNH aggregates were produced with a yield of 95% when Ar at 760 Torr was used as the buffer gas, while “bud-like” SWNH aggregates were formed with a yield of 70 or 80% when either He or N2 at 760 Torr was used. The internal structures of both aggregates were studied by partially burning them in an O2 atmosphere. We were then able to examine the mechanism for the formation of SWNH aggregates.