Irradiation of CW-CO2 laser on a powder target. Formation of fullerene film from graphite powder

A process was investigated to irradiate a continuous-wave CO2 laser (4.5 kW) on graphite powder with a mean diameter of 5 μm in a flow of Ar or He gas at 30 or 200 Torr. The film produced on a Ni substrate in the Ar flow at 200 Torr showed the Raman bands of C60 and C70, and the C60/C70 ratio was estimated to be 5/1 by MALDI-TOF mass spectrometry. The film formation process is discussed on the basis of an analysis of laser-irradiated powder, which included 0.01 wt% of C60, by UV–Vis absorption, and by observations of the plumes and SEM images.