Near edge X-ray absorption spectroscopy of DNA damage induced by soft X-rays

Fujii, Kentaro; Yokoya, Akinari

We have investigated the change of the spectra of the near edge X-ray absorption fine structure (NEXAFS) of DNA exposed to monochromatic soft X-rays. We used calf thymus DNA thin films as samples and observed N K-shell and O K-shell NEXAFS spectral changes. The typical monochromatic soft X-ray energies used for the irradiation (380, 435, 560, and 760eV) were obtained from SPring-8, BL23SU. The observed spectra show the initiation of the new products and the dissociation of molecular structure of the DNA by the irradiation. By comparing the spectral changes in NEXAFS with the yields of base lesions and strand breaks, we will discuss the molecular structure of DNA damage site and the site-selectivity of damage induction in DNA by soft X-rays.