Experimental evidence for high-yield C74 production in an arc periphery plasma

Spatial profiles and buffer-gas pressure dependences of fullerenes contained in primary carbon soots are measured in order to investigate production ratios of higher fullerenes to ${\mathrm{C}}_{\mathrm{60}}$ in an arc-discharge fullerene generator. It is found that ${\mathrm{C}}_{\mathrm{74}}$ is efficiently produced in the arc periphery-plasma region while ${\mathrm{C}}_{\mathrm{60}}$ is mainly produced in the core-plasma region, being the most dominant higher fullerene under the condition of a higher helium-gas pressure $\text{(>100\hspace{0.17em}}\mathrm{Torr}\mathrm{).}$