Development of a Pulse Radiolysis System by Ultra-fast Super Continuum Probe Light at Waseda University*

We have been studying the pulse radiolysis using photo-cathode rf gun at Waseda Univ. Pulse radiolysis is one of the powerful methods to trace early chemical reactions by ionizing radiation. In pulse radiolysis, the probe light absorption, which produced by active species formed by electron beam of rf gun, is measured at each wavelength and made possible to trace reactions. Therefore, we have used the super continuum (SC) light for the probe light. The SC light has a broad spectrum and is generated by nonlinear optical effect caused by injecting picosecond laser to photonic crystal fiber (PCF). However, the resulting SC light was unstable because its peak intensity was not enough. We need to use a femtosecond pulsed laser which is expected to be stronger peak intensity than a picosecond laser. We have developed a mode-locked Yb-doped fiber laser based on Non-Linear Polarization Rotation as a femtosecond pulsed laser and the chirped pulse amplification system which will be able to amplify the femtosecond pulse. In this conference, we will report the performance of the SC light using this fiber laser system, recent results of pulse radiolysis experiments and the future plans.