ENHANCEMENT OF FLUORESCENCE AND RAMAN SPECTROSCOPIES OF UNDOPED C-60 FILM

The spectroscopic characteristics of C-60 films deposited on different substrates have been investigated at room temperature. We find that t he fluorescence of C-60 film is enhanced by the presence of a rough si lver surface and also by oxygen under excitation at 5145 Angstrom (2.4 1 eV) at room temperature. The enhancement of the fluorescence on the rough silver surface is mainly due to an appropriate work function of the silver surface and an external electromagnetic field induced by la ser irradiation, which leads to a resonant coupling with the C-60 mole cular dipole. The fluorescence enhancement by oxygen is interpreted as resulting from the strong reduction in symmetry of C-60 from I-h to C -2, or lower due to photooxygenation of the C-60 molecules. This also results in larger Jahn-Teller distortions. The kinetics of the photoch emical reactions between oxygen and C-60 have also been obtained with an observed rate constant of magnitude about 1.6 x 10(-2) s(-1) by mon itoring the changes of the fluorescence and Raman spectra with the irr adiation time.