Photoinduced transformation of luminescence centers in C-60 crystals at high pressure

The influence of laser irradiation on the photoluminescence spectra of perf ect C-60 crystals in the orientationally disordered phase is investigated. It is shown that irradiation of the crystals with low-power light for short durations at T=200 K produces radical changes in the luminescence spectrum . The pressure dependences of the spectral bands of the phototransformed an d initial (without irradiation) spectra differ significantly, indicating a photoinduced structural transformation of the X centers responsible for the luminescence of C-60. The phototransformed C-60 crystals are stable agains t further exposure to light irradiation and pressure. (C) 1999 American Ins titute of Physics. [S0021- 3640(99)00424-7].