High Resolution Transmission Electron Microscopy

Terrestrial and Extraterrestrial Fullerenes

“…[132] Are there any reasons to expect formation of small quantities of fullerenes from algal remains? As we have argued in Section 3.4.1, biogenic PAHs might have been transformed to C 60 .…”

“…Allende is exceptional because the element is a poorly ordered carbon, characterized from studies by transmission electron microscopy as ''glassy carbon''. [60,61] A more recent TEM study of Allende carbon supports this finding and reports the abundant occurrence of ''carbon black-like particles'' Vis et al [62] Taken together these observations suggest that Allende carbon formed by pyrolysis of hydrocarbons and polymeric hydrocarbons, in part in a gas phase, in part perhaps on hot mineral surfaces. Such a scenario for the formation of fullerenes is not too outlandish when one considers that fullerenes have been synthesized by the pyrolysis of naphtalene [63] and by the consecutive=multiple cyclodehydrogenation of even more complex trimerized PAHs.…”

“…Whether C 60 À ions can form either by free electron attachment or by electron transfer with negatively charged PAHs is not clear. Once formed, however, C 60 À ions should be quite stable given the high electron affinity of the neutral molecule. The three positive ions can react, however, with various molecules in interstellar clouds.…”

“…Fullerene multimers, because of their very low solubilities in organic solvents, are very hard to detect. An additional loss mechanism from the equatorial region of the Moon is due to the estimated relatively short sticking time of 270 s of C 60 at the very top of the regolith of the two landing sites. That time rapidly lengthens towards the cooler lunar Poles, which means that fullerenes could have slowly migrated north-and southward away from the more equatorial Apollo sampling areas.…”

“…Astronomers almost immediately began searches for fullerenes and fullerene derivatives in interstellar and circumstellar media. When Krätschmer et al [2] first synthesized macroscopic amounts of C 60 and discovered that the fullerenes were soluble in organic solvents such as toluene and in CS 2 , the search for fullerenes in terrestrial and extraterrestrial rocks became possible and began. All searches had in common not only the excitement of the hunt, but, if fullerenes were found, speculations on how and where these had formed in the first place.…”