Improved Spectrophotometric Analysis of Fullerenes C60 and C70 in High-solubility Organic Solvents

Fullerenes are among a number of recently discovered carbon allotropes that exhibit unique and versatile properties. The analysis of these materials is of great importance and interest. We present previously unreported spectroscopic data for C₆₀ and C₇₀ fullerenes in high-solubility solvents, including error bounds, so as to allow reliable colorimetric analysis of these materials. The Beer-Lambert-Bouguer law is found to be valid at all wavelengths. The measured data were highly reproducible, and yielded high-precision molar absorbance coefficients for C₆₀ and C₇₀ in o-xylene and o-dichlorobenzene, which both exhibit a high solubility for these fullerenes, and offer the prospect of improved extraction efficiency. A photometric method for a C₆₀/C₇₀ mixture analysis was validated with standard mixtures, and subsequently improved for real samples by correcting for light scattering, using a power-law fit. The method was successfully applied to the analysis of C₆₀/C₇₀ mixtures extracted from fullerene soot.