Measurement of two-photon and three-photon ionization processes of N2 by intense XUV free electron light.

A cooperative research group composed of six research institutes (The University of Tokyo, KEK, Keio University, JAEA, RIKEN, NTT) led by The University of Tokyo collaborated RIKEN SPring-8 XFEL project and uncovered the existence of two-photon and three-photon ionization processes of N,2 by irradiating intense XUV light (50.3 nm) of compact self-amplified spontaneous emission free electron laser in SPring-8 center built as a prototype accelerator of X-ray free electron laser under construction from the analysis of time-of-flight mass spectrum for the first time. The result shows that the newly built FEL light source in the XUV wavelength range is unprecedently intense and is a promising light source for molecular science in the intense short-wavelength light field. This study was supported by the X-ray Free Electron Laser Utilization Research Project of the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT).
Research results were published in Applied Physics Letters, Vol. 92 Issue 15 on April 14th. The achievement was also announced in the Graduate School of Science website as well as in the RIKEN homepage (press release).