Liquid-microjet synchrotron-radiation spectroscopy for biomolecules in water solution 1

A new spectroscopic research of radiation induced damage on DNA and its constituent molecules is proposed, which is made possible using a liquid micro-jet technique for bio-solution under vacuum in combination with synchrotron-radiation aided site-selective excitation. We emphasize a view point of time-evolutional production and destruction of irregular chemical species characteristic of time domains after irradiation, which finally result in the alternative processes to give rise to a irreparable damage or to avoid it by a thermodynamical restoration. Up to now a method of spectroscopy to identify the initial molecular site of radiation interaction is almost completed. The former part of the proposal article is presented in this volume. We describe the objectives of the new spectroscopy for observing the early processes of direct radiation effect on DNA leading to damage induction using a site-selective synchrotron-radiation excitation to identify the initial site of radiation interaction. The present status of development is described by presenting the new results of the spectra of X-ray absorption near edge structure and ejected electron energy spectra for liquid water as examples. The forthcoming latter part of this article will discuss the conformational and electronic structure of nucleotides in water solution prior to time evolution. (author)