Electronic and vibrational spectra of C60 complexes at high pressures

Electronic and FTIR spectra of neutral C60 complexes were measured at high pressures by use of a diamond anvil cell. A new absorption band, which was assigned to a π-π∗ transition of C60−, was observed around 1000 nm for (BEDT-TTF)2C60, (ferrocene)2C60 and HMTTeF-C60 at 3.8, 0.8 and 0.9 GPa, respectively. The results indicate an increase in the ionicity of the complexes by contraction of the crystal lattice with increasing pressure.