Formation of fullerene(C60) by laser ablation in superfluid helium at 1.5Â K

C60 fullerene was detected in the deposit produced by the laser ablation of graphite rod in the superfluid helium at 1.5 K. From the mass spectrometry, it was found that the ratio, 12C60/12C5913C, differs from statistical one calculated by Poisson distribution for natural graphite. Assuming the recombination of atomic carbons to C2 molecules as an initial stage for C60 formation, the different isotopic ratio within C60 from Poisson statistics was ascribed to the tunneling recombination between 12C and 13C atoms in the bubble state.