engleski

Vibronic fine structure in high-resolution x-ray absorption spectra from boron nitride nanotubes

We have applied high-resolution near-edge x-ray absorption fine structure measurements around the nitrogen K-edge to study vibrational effects in boron nitride nanotubes. A notable difference has been observed between surface sensitive partial electron yield (PEY) and bulk sensitive total electron yield (TEY) fine-structure measurements. The PEY fine structure, interpreted as vibronic coupling to electronic core excitations, is assigned to NO molecules trapped just below the surface. The creation of NO molecules is significantly enhanced by low energy ion bombardment, as broken B-N bonds are replaced by N-O bonds involving oxygen present in the surface region. In contrast to PEY spectra, the bulk sensitive TEY measurements on as-grown samples do not exhibit any fine structure while the measurements on ion-bombarded samples show a clear vibronic signature of molecular nitrogen.

vibronic structure; NEXAFS; BNNT

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