Intense soft X-ray illumination near the carbon core edge induces significant structural damage in tetrahedral amorphous
carbon films and less significant but detectable defect formation in single-walled carbon nanotubes (SWNTs). The
efficiency spectra of the photo-induced damage commonly show a resonant peak between the π* and σ* peaks of X-ray
absorption spectra in addition to a non-resonant background. The resonant damage cannot be explained by the coreexciton
mechanism but can be attributed to a recoil damage accompanying the photo-desorption of heavy chemisorbates
that is resonantly decomposed by the spectator Auger mechanism. The cause of the non-resonant damage in SWNTs may
be attributed to anomalous radiation damage by low-energy electrons generated by secondary effects of soft X-ray
illumination, which is supported by the recent finding by authors that hot electron injection from probe tips of scanning
tunneling microscopes generates defects in the SWNT samples.
Effects of carbon 1s core excitations on the structure of tetrahedral amorphous carbon films were investigated by
illuminating samples with intense soft X-rays from a synchrotron radiation source in the photon energy range of 240 eV
to 310 eV. The structural changes detected in the X-ray absorption spectra obtained before and after the intense
illumination are characterized by graphitic ordering, similar to the effect of high-energy electron irradiation. The
excitation spectrum for the photo-stimulated structural changes was found to consist of a non-resonant component and a
resonant component peaking at 289 eV close to the 288 eV XAS peak characteristic of ta-C films. The microscopic
mechanisms are discussed for the non-resonant and the resonant effects.
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