Unpaired Electron Species in Thin Films of Calf-Thymus DNA Molecules Induced by Nitrogen and Oxygen $K$-Shell Photoabsorption

Unpaired Electron Species in Thin Films of Calf-Thymus DNA Molecules Induced by Nitrogen and Oxygen $K$ -Shell Photoabsorption

T. Oka, A. Yokoya, K. Fujii, Y. Fukuda, and M. Ukai

Phys. Rev. Lett. 109, 213001 – Published 20 November 2012

Abstract

The mechanism of DNA modification induced by $K$ -shell photoabsorption of nitrogen and oxygen atoms was investigated by electron paramagnetic resonance and x-ray absorption near edge structure measurements of calf thymus DNA. A $g$ factor of 2.000 for the unpaired electron species, which only arises during irradiation, was measured. The EPR intensities for DNA zwere twofold times larger than those estimated based on the photoabsorption cross section. This suggests that the DNA film itself forms unpaired electron species through the excitation of enhanced electron recapturing, known as the postcollision interaction process.

Received 20 March 2012

DOI:https://doi.org/10.1103/PhysRevLett.109.213001

Authors & Affiliations

T. Oka^*, A. Yokoya^†, and K. Fujii

Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan

Y. Fukuda

Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1-1-1, Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan

M. Ukai

Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei-shi, Tokyo 184-8588, Japan

^*Present address: The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan. kotobuki@sanken.osaka-u.ac.jp
^†yokoya.akinari@jaea.go.jp

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Vol. 109, Iss. 21 — 21 November 2012

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