Fragmentation in biological molecules by the irradiation of monochromatized soft X-rays

Abstract

Abstract High-flux photons from FEL can be used not only for the structural analysis but also for the materials modification. In advance of future application of short wavelength light from FEL, we present the results for photo-fragmentation in biological molecules by monochromatized soft X-ray irradiation using synchrotron radiation. For sulfur-containing amino acids, the core-to-valence resonant excitation at the sulfur AT-edge induced the desorption of only S + ions, which is quite different from the fragmentation patterns by the valence excitation. On the basis of the Auger decay spectra, it is revealed that the resonance excitation from the S ls to σ * states is followed by the “spectator-type” Auger decay where the excited electrons remain in the σ * orbital in the course of Auger decay. We conclude that the specific fragmentation is caused by the fast bond scission due to the highly antibonding character of the σ * orbital. PACS codes: 32.80. Hd, 68.43. Tj, 82.S0. Kx