WAVELENGTH DEPENDENCE OF THE PHOTOINDUCED INDENTATION HARDENING IN C-60 CRYSTALS

The photoinduced indentation hardening of C-60 crystals was investigat ed in ultraviolet-visible light. The hardening strongly depended on th e wavelength of the illumination light: the magnitude increased with i ncreasing wavelength, and then reached a maximum at 700 nm. This indic ated that red light is more effective than ultraviolet light in the ha rdening. The wavelength dependence of the hardening is discussed in te rms of an interplay between the effective depth of the photoinduced po lymerization and the penetration depth of the indenter. (C) 1998 Ameri can Institute of Physics. [S0021-8979(98)09316-5].