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Laser-induced dissociation of C60 into C32 and smaller carbon species

This study investigates the sequential loss of C2 fragments from C60, resulting in the formation of C32 and subsequent explosive fragmentation. The stability and properties of C28 and C32 are examined, with predictions made based on strain release and aromatic ring stability. Endohedral fullerenes, including Ti@C28 and Zr@C28, are also analyzed using laser vaporization techniques and FT-ICR-MS.

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Laser-induced dissociation of C60 into C32 and smaller carbon species

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  1. Laser photodissociation caused C60 to lose C2 fragments sequentially down to C32 at which time point C32 exploded into atoms and small non-fullerene Cn species Rice Group

  2. Instead of C32

  3. C28 Polaroid image of the first molecular model of C28 HWK Nature, 329, 529 (1987)

  4. C28 MS (Rice/Sussex unpublished result 1985)

  5. Prediction C28 tetravalent and should be stabilised by addition of four H atoms HK Nature 1987

  6. Prediction: because strain released and four C6 aromatic rings remain HK Nature 1987

  7. Giant tetravalent “Superatom” H W Kroto, Nature, 329, 529 (1987)

  8. Ti@C28 C32 FT-ICR-MS of Titanium Carbon Clusters

  9. At FSU we decided to investigate the creation and properties of C28 in detail starting with Ti@C28 Ti with Paul Dunk and Alan Marshall

  10. U U@C28

  11. U@C28 Laser vaporization of a UO2-graphite target laser fired at different points in time along the pulse pressure profile U@C28 is clearly seen to form before larger U@Cn species

  12. C28 U@C28 U@C36

  13. C28 C32 C50 C60 C70 Predicted stable and semi-stable Fullerenes image at: www.answers.com/topic/fullerene

  14. Exxon Data Cox et al JACS 110 1588 (1988) NB No C22 possible!

  15. Ti@C32 Ti@C32 Only Cn n even clusters Ti mass 48 = 4x12 Ti@C28 Ti@C30 C27 C28 C23 C26 C31 C25 C30 C24 C29 C22 FT-ICR-MS Titanium Carbon Clusters

  16. The detection of U@C28 confirmed that C28 is tetravalent and stabilised endohedrally U Rice group 1993

  17. Ti@C28 observed when the pure C28is not detected Cn Ti@C28 Ti@Cn

  18. Molecular and Schlegel representations of Ti@Td-C28. The internally located Ti atom is located off center, yielding additional stabilization.

  19. Zr Zr@C28

  20. Laser vaporization of a rod UO2 (0.8 atom %) graphite enriched with 13C amorphous carbon 10 atom % U@C28 incorporates all enriched 13C

  21. The main isotope of Ti has mass 48 amu …so mass C32 ~ Ti@C28

  22. Cn Ti@C28 Ti@Cn no C28

  23. Cn Ti@C28 Ti@Cn

  24. Ti@C28 C32 C32 Ti@C28 C27 C23 FT-ICR-MS of Titanium Carbon Clusters

  25. n = 32 34 36 38 Ti@Cn Endohedral fullerenes even only FT-ICR-MS of Titanium Carbon Clusters

  26. neutral C28 C284- Ti@C28 Electrostatic potentials Charge is transferred from Ti and localized at the four pyramidalised carbon atoms (with Poblet)

  27. Rice Group showed that under intense laser irradiation C60 lost C2 fragments sequentially and at C32 blew up completely into small carbon species and atoms C60→ C58 → C56 → → → → C32 → C2 C2 C2 Cn (n small)

  28. I decided to play with a molecular model kit to see what the C32 structure might be – just like a kid again

  29. I decided to play with molecular model kit to see what C32 structure might be

  30. Endohedral Fullerenes can satisfy “valencies” internally

  31. U@C28 is also a highly favored species.

  32. neutral C28 Ti4+@C284- Electrostatic potentials Negative charge is transferred from Ti and localized at the four pyramidalised carbon atoms

  33. Ti@C28 C32 FT-ICR-MS of Titanium Carbon Clusters

  34. Zr@C28 Zr@C28 is the smallest endohedral fullerene formed C32 is the smallest empty cage. Zr@C28 is not as favored as Ti@C28.

  35. The structure proposed for C28 contains four triple fused pentagons units arranged in tetrahedral symmetry.

  36. Sussex NNC

  37. Sussex NNC

  38. ~sp3 Sussex NNC

  39. Four Benzenoid aromatic rings remain

  40. C44 C28 Cn Ti@C28 Ti@C44

  41. Cn Ti@Cn 26 28 30 32 34 36 38 40 42 44 46 48 50 Ti@Cn distribution (Red)vs.empty cage distribution (Blue) Clearly shows titanium stabilizes C28 and other small fullerenes.

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