Journal of Physical Chemistry A, Vol.102, No.18, 3083-3088, 1998
High-temperature reactions of fullerene C-60 with H and OH
The reactions of H atoms and OH radicals with fullerene C-60 were studied behind reflected shock waves by time-dependent absorption measurements. Shock-heated mixtures of C2H5I highly diluted in argon were used as a source for H atoms, and their absorption at lambda = 121.6 nm was monitored using the highly sensitive ARAS technique. In a second series of experiments OH radicals were generated in H-2/N2O/Ar reaction systems, and the absorption of OH was monitored at nu = 32 403.41 cm(-1) using ring dye laser absorption spectroscopy (RDLAS). In each case, the respective mixtures were perturbed by C-60 Simultaneously with the absorption measurements, emission spectroscopy with an intensified CCD camera was used to acquire additional information about the reaction systems. The H atom experiments were performed at temperatures between 2100 and 2300 K, while OH absorption was measured in the temperature range 2020 K less than or equal to T less than or equal to 2540 K. Postshock pressures were around 1.30 bar for all experiments. From the H-absorption measurements, an upper limit for the reaction C-60 + H to products (R9) (k(9) < 1.0 x 10(12) cm(3) mol(-1) s(-1)) was determined. For the H-2/N2O/Ar + C-60 reaction system, different kinetic models were discussed to verify the measured OH absorption. The reaction C-60 + OH to products (R7) (k(7) = 1.0 x 10(15) exp(-6030 K/T) cm(3) mol(-1) s(-1)) with the given rate coefficient represents the experimental findings quite well.