Formation of C H Ablation of Graphite, Coal or C Particles Suspended in Selected Solvents - Polyynes: Synthesis, Properties, and Applications - page 125

1064 nm laser irradiation. In order to obtain more information on the
formation mechanism of polyynes from suspension of graphite particles,
absorbances of polyynes in toluene are measured as a function of the
concentration of the graphite particles, the laser power, or the laser irra-
diation time at 355 nm laser irradiation. The relative abundance of polyynes
from graphite, coal, and C 60 particles is compared and their formation
mechanism from each carbon source by laser ablation in solutions is
discussed.
7.2 EXPERIMENTAL
Figure 7.1 shows a schematic view of laser ablation apparatus in solutions
used for the formation of polyynes. Small particles of graphite (Kishida
Chem. diameter 75 m m), coal (Indonesian TanitoHarum or AustralianWork-
worth), or C 60 (MER corporation) were suspended in a selected solvent. The
amount of particles used was 0.05-0.1 g per 10ml. Elemental analyses of
Tanito Harum and Workworth coals showed the following C:H:N:O ratios:
71.2:4.4:1.6:21.7%and 79.9:5.6:1.6:12.8%, respectively. As solvents, benzene,
toluene, hexane, cyclohexane, methanol, hexafluorobenzene, perfluoro-
octane, and perfluorodecaline (Kishida Chem Ind. Tokyo Kasei, or Azmax
spectral grade) were used for graphite, hexane was used for coals, and
hexane and methanol were employed for C 60 .
The experiments were performed using fundamental (1064 nm) and
frequency-multiplied outputs (532, 355, and 266 nm) of a Nd:YAG laser
(Spectra Physics GCR-100 or Continuum Surelight I-10). The energy of
the Nd:YAG laser was generally maintained at 40mJ/pulse (200mJ/cm 2 )in
FIGURE 7.1 Laser ablation cell of various kinds of carbon particles suspended in
solution.