High pressure study of the 2D polymeric phase of C-60 by means of Raman spectroscopy

The effect of high hydrostatic pressure, up to 12 GPa, on the intramolecula r phonon frequencies and the material stability of the two-dimensional tetr agonal C-60 polymer has been studied by means of Raman spectroscopy in the spectral range of the radial intramolecular modes (200-800 cm(-1)). A numbe r of new Raman modes appear in the spectrum for pressures similar to 1.4 an d similar to 5.0 GPa. The pressure coefficients for the majority of the pho non modes exhibit changes to lower values at P=4.0 GPa, which may be relate d to a structural modification of the 2D polymer to a more isotropic phase. The peculiarities observed in the Raman spectra are reversible and the mat erial is stable in the pressure region investigated.