Synthesis evaluation of nitrogen atom encapsulated fullerenes by optical emission spectra in nitrogen plasmas

The nitrogen atom encapsulated fullerene (N@C60) with relatively high yield has been synthesized by a plasma irradiation method. We have examined the relationship between optical emission spectra of a radio frequency (RF) discharge nitrogen plasma and the synthesis yield of N@C60. As a consequence, the increasing amount of nitrogen molecule ions (N2+) impinging on the sublimated fullerenes are found to enhance the synthesis of N@C60. Furthermore, it is clarified that there is an optimum condition of the nitrogen plasma for the high-yield synthesis of N@C60, which is generated under lower gas pressure and is irradiated to the larger amount of fullerenes.