Humic substances extracted from swamp water and peat were studied by laser ablation Fourier transform ion cyclotron resonance mass spectroscopy using the fundamental frequency of Nd:YAG laser (1064 nm).

Preliminary results from laser ablation positive-ion mass spectra of humic substances show that humic substances, using both low (4 - 200 kW cm^-2) and high laser power (100 - 3000 MW cm^-2), initially did not produce any fullerene ions but after continued ablation a cavity was formed in the target and a wide range distribution of fullerene ions was produced with subsequent laser pulse. The mass spectra from swamp humic substances show peaks of high intensity, indicating formation of large-mass carbon cluster ions after continued ablation, showing that cavity formation is essential to produce fullerenes.

Humic substances extracted from swamp water show the formation of C₆₀, C₇₀ and other positive fullerene ions up to m/z 3000. No negative C₆₀ and C₇₀ clusters have been observed in the mass spectra from the humic substances. Humic substances extracted from peat also show the formation of positive fullerene ions under similar experimental conditions. Humic substances from these two sources produce similar mass spectra distributions, since these humic substances have similar atomic ratios of H to C and have similar molecular structure units. It appears that the ease of fullerene formation from raw humic substances without pyrolysis may be due to the low ratio of H/C of humic substances because elemental analysis of humic substances extracted from both swamp water and peat show that the ratios of H to C are 0.83 and 0.78 respectively.

However, when the humic substances were pyrolysed at 350 to 400°C and the residue was subjected to laser ablation, a much smaller amount of fullerene ions were produced. This is possibly due to the formation of a large polycyclic aromatic system at pyrolysis temperatures above 350°C. Further work on this system is continuing.