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A reflectron type time of flight mass spectrometer with supersonic cluster beam source was implemented. Carbon cluster was generated by the laser vaporization of graphite sample disk followed by cooling with supersonic expansion of pulsed helium gas. The neutral cluster carried by helium was ionized by the 3rd harmonics of Nd: YAG laser and accelerated by the high voltage to the mass spectrometer. Positive ion time of flight mass spectra of carbon cluster showed the characteristic bimodal distribution. Only even numbered clusters were observed in the range of C30 - C120 with a remarkable peak of C60. By changing the timing of pulsed valve and vaporization laser, we had estimated the optimum condition of gas pressure for the most efficient production of fullerene.
Laser vaporization & supersonic expansion cluster source used for the TOF mass-spectrometer.