X-ray damage in protein-metal hybrid structures: a photoemission electron microscopy study.

ABSTRACT

Bacterial surface layer protein sheets (S layer) coated with an ultrathin cobalt or silver film were studied by means of laterally resolved near-edge X-ray absorption fine structure spectroscopy performed by photoemission electron microscopy. Comparison with results obtained on pristine S layers allowed us to characterize both chemical interaction and X-ray damage in these protein-metal hybrid systems. In particular, we found that besides direct damage upon exposure to X-ray radiation the biomolecules experience additional contribution of the deposited metals, by low-energy electron generation in the metal particles.