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Successful Dead-Time-Free Simultaneous Detection of Charged Particles - Major step in structural analysis of single molecules using XFEL (Press Release)

Release Date
18 Mar, 2009
  • SCSS test accelerator

Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
Kyoto University
Japan Synchrotron Radiation Research Institute

Key research achievements
• Successful detection of many charged particles without dead time
• Determination of the dependences of the Coulomb explosion of nanoclusters on laser intensity and cluster size
• Realization of XFEL structural analysis of a single molecule through identifying its orientation in a space

A joint research team consisting of Kiyoshi Ueda, a professor of the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University; Makoto Yao, a professor of the Graduate School of Science, Kyoto University; Norio Saito, General Manager of the Metrology Institute of Japan, Advanced Industrial Science and Technology; and scientists at the Max Planck Institute and the University of Frankfurt developed a system that can detect a large number of charged particles without dead time under collaboration with a joint research group of the "SPring-8 Joint Project for XFEL" launched by RIKEN and the Japan Synchrotron Radiation Research Institute (JASRI). They succeeded in detecting several tens of ions instantaneously generated upon laser irradiation without dead time*4 using the developed system. To generate the ions, they irradiated a high-intensity laser light in the extreme ultraviolet range from an X-ray free electron laser (XFEL)*1 prototype accelerator (an SCSS test accelerator*2) to a rare-gas cluster*3 composed of 100 or more atoms. The XFEL accelerator is currently under construction at the Harima Institute, RIKEN SPring-8 Center. As a result of this research, the orientation of individual biomolecules and nanostructures can be determined, thus realizing the structural determination of single molecules using an XFEL.
The result of this research was published in the online version of the scientific journal Physical Review A prior to publication in the printed version.

"Dead-time-free ion momentum spectroscopy of multiple ionization of Xe clusters irradiated by euv free-electron laser pulses"
H. Fukuzawa, X.-J. Liu, G. Prümper, M. Okunishi, K. Shimada, K. Ueda, T. Harada, M. Toyoda, M. Yanagihara, M. Yamamoto, H. Iwayama, K. Nagaya, M. Yao, K. Motomura, N. Saito, A. Rudenko, J. Ullrich, L. Foucar, A. Czasch, R. Dörner, M. Nagasono, A. Higashiya, M. Yabashi, T. Ishikawa, H. Ohashi, and H. Kimura
Physical Review A 79, 031201(R) (2009), published online 24 March 2009

Fig. 1 Schematic of experiment. Fig. 1 Schematic of experiment.

Fig. 2 Dependences of kinetic energy distribution on laser intensity (left) and the number of atoms constituting the cluster (right). Fig. 2 Dependences of kinetic energy distribution on laser intensity (left) and the number of atoms constituting the cluster (right).

*1 X-ray free electron laser (XFEL)
The XFEL is listed as one of the five national critical technologies in the Third-Stage Basic Plan for Science and Technology of Japan. The XFEL facility is being constructed by RIKEN adjacent to SPring-8 with the aim of being open for public use in fiscal 2011. The XFEL project aims to produce a perfectly coherent laser in the X-ray range that is a billion times brighter than the X-rays at SPring-8, has an extremely short pulse, i.e., one-thousandth of that of the X-rays at SPring-8, and a minimum wavelength of 0.06 nanometers (a nanometer is one-billionth of a meter), unlike conventional lasers, using free electrons that are not bound to a substance. The XFEL will enable us to capture the atomic world on a femtosecond scale (a femtosecond is one-quadrillionth of a second). Accordingly, it is hoped that the XFEL can be used to achieve epoch-making results ahead of the rest of the world in a wide range of areas from basic research studies to applied research and development that will be useful for industry and our daily lives. In concrete terms, it is expected that the XFEL will contribute to various fields including life science and nanotechnology, for example, the development of effective drugs for intractable diseases such as cancer and AIDS and the study of new energy systems required for sustainable development.

*2 SCSS test accelerator
SCSS is an abbreviation of SPring-8 Compact SASE Source. The SCSS test accelerator was constructed as a prototype for XFEL at the Harima Institute, RIKEN SPring-8 Center. This test accelerator has an acceleration energy of 250 MeV, which is 32 times smaller than the acceleration energy for the XFEL, and can generate a free-electron laser with a wavelength of 51-61 nm. It is 60 meters long. SASE is an abbreviation of self-amplified spontaneous emission.

*3 Cluster
A small group of atoms or molecules.

*4 Dead time
The time required after the detection of a signal until the system becomes ready to detect the next signal. The system cannot detect any signals during the dead time.

For more information, please contact:
for research results,
Prof. Kiyoshi Ueda (Tohoku University)
e-mail: メール


Prof. Makoto Yao (Kyoto University)
e-mail: メール,

for the XFEL project and the SCSS test accelerator,
Dr. Mituru Nagasono (RIKEN Harima Institute)
e-mail: メール.