DEGENERATE 4-WAVE-MIXING AS A NONLINEAR-OPTICAL PROBE OF THE FULLERENES

Time-resolved degenerate four-wave mixing experiments were conducted on pure C-60 and chemically modified C-60 using a picosecond tunable dye laser. Photopolymerization, oxygen doping or formation of charge transfer complexes in the ground or excited states were used to alter the electronic and chemical structure of C-60. The third-order optical response for C-60 was largely unaffected by photopolymerization or oxygen-doping whereas significant enhancements were observed for a C-60:phenylenediamine derivative charge transfer complex and for a C-60/substituted-polyphenylenevinylene composite. The chemical modification of C-60 has a strong influence on the dynamics of the third-order response and gives rise to differing mechanisms.