An FT-ICR study on laser ablation of graphite and carbon black targets: Cosmochemical implications

Graphite and carbon black samples were laser ablated in an FT-ICR (Fourier transform-ion cyclotron resonance spectrometer) by Nd-YAG laser under high vacuum in conditions recalling those existing in the interstellar medium. I t is shown that graphite gives a regular sequence of polyyne and cyclopolyy ne chains from C-10 to C-27 and additionally produces 2% of C-60 fullerene. When carbon black is used in place of graphite under the same conditions, no C-60 fullerene was produced and also the sequence of polyyne species gen erated was very irregular. If really carbon black structure and elemental c omposition approaches more closely than pure graphite the structure of the carbon dust, we can predict that C-60 fullerene should not be produced from the thermal decomposition of this dust in high vacuum.