Laser-induced fluorescence line-narrowing of C-60-hydroquinone crystals

The low temperature optical spectroscopy of C-60-hydroquinone (C-60(HQ)(3)) crystals has been studied by fluorescence line-narrowing and total luminescence spectroscopy. The spectra are characterized by sharp zero-phonon lines and phonon sidebands of neutral C-60. Symmetric h(g) and a(g) modes and progressions in the Jahn-Teller active 260 cm(-1) h(g) squashing mode dominate the fluorescence spectra indicating the hexagonal environment of the crystal has distorted the C-60 icosahedral symmetry. There may also be a Jahn-Teller distortion of the excited state. The line-narrowing experiments show there is substantial inhomogeneous broadening because of rotational disorder in the crystal.