Observing Drastic Translation of X-Rays by a Deformed Single Crystal - A crystal with a microscopic deformation, i.e., a disorder in the atomic arrangement, translates X-rays by the order of a millimeter. (Press Release)
- Release Date
- 10 Jun, 2010
- BL19LXU (RIKEN SR Physics)
RIKEN
Key research findings
• Observation of X-ray translation by deformed silicon single crystal near the Bragg angle
• Demonstration of drastic translation of X-ray, theoretically predicted in 2006
• Enabling the application of discovered X-ray translation to high-speed optical switching devices
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Scientists at RIKEN (Ryoji Noyori, President) experimentally observed, for the first time, that SPring-8 X-rays with a wavelength of 0.08 nm (1 nm = 10-9 m) irradiated to a deformed silicon single crystal were translated by as much as 5 mm when the incident angle was near the Bragg angle.*1 This was achieved by Yoshiki Kohmura, Leader, and Tetsuya Ishikawa, Chief Scientist, of the Synchrotron Radiation (SR) Imaging Instrumentation Unit at the RIKEN SPring-8 Center (Tetsuya Ishikawa, Director), and Kei Sawada, a research scientist of the Experimental Facility Group of the RIKEN SPring-8 Joint Project for the X-ray free-electron laser (XFEL) (Nobuo Fujishima, Director). Electromagnetic waves in the X-ray region are highly penetrating and interact negligibly with objects; therefore, it has been very difficult to develop optical devices exclusively for X-rays, compared with electromagnetic waves, for which optical systems can be freely established using mirrors and lenses, similarly to visible light. Previously, the translation of an X-ray optical path was at most on the nanometer scale. However, the research group discovered that an X-ray optical path can be translated by millimeters, approximately a million times more than before, which presents a possible solution to long-standing problems in the development of X-ray optical devices. Scientists in the research group set the incident angle of X-rays with respect to a slightly deformed silicon single crystal to be approximately 18°, near the Bragg angle. Upon the irradiation of 0.2-mm-wide X-rays with a wavelength of 0.08 nm, they observed that the X-rays were translated by as much as 5 mm and exited from the crystal as an extremely thin, highly parallel beam of 0.04 mm width. They succeeded in macroscopically controlling the X-ray optical path using a crystal with a microscopic deformation, i.e., a disorder in the atomic arrangement, by which X-rays are translated at millimeter order along the crystal plane, despite the common knowledge that X-rays are negligibly deflected by objects. The application of this phenomenon to medical devices will enable us to minimize X-ray exposure by irradiating a thin beam only to a small lesion. In addition, devices developed using the results of this study can be applied as high-speed optical switching devices using the XFEL*2 currently being constructed at SPring-8, possibility contributing to the snapshot observation of atomic motion. This research was supported by Grants-in-Aid for Scientific Research (B) under the theme "Observation of abnormal shift of X-ray wave packet by crystal under the Bragg reflection condition and its application to X-ray waveguide tubes." The achievements of this research were published online as a highlighted paper in the American scientific journal Physical Review Letters on 14 June 2010. Publication: |
<Figure>
Fig. 1 Schematic of crystal deformation
The dashed lines represent crystal planes without deformation.
Fig. 2 Schematic of discovered drastic translation of X-rays
An X-ray beam is drastically diffracted in the deformed region of a crystal before reaching the end of the crystal. After exiting the crystal, the X-ray beam travels in the direction parallel to that before entering the crystal.
Fig. 3 Distribution of X-ray intensity observed after passing through crystal
| Left: | When the incident angle deviates greatly from the Bragg angle; Similarly to a beam before entering the crystal, a single peak (red) was observed. |
| Right: | Near Bragg angle; The peak observed in the left figure (red area) was split into two. The region where the transmission intensity decreased (blue) as a result of Bragg reflection when the Bragg reflection condition was satisfied (upper arrow). A peak of the 0.04-mm-width beam with an increased intensity appears (thin red area, indicated by the lower arrow) below the peak observed in the left figure (red). This is caused by the drastic translation of X-rays that reached the end of the crystal. |
<Glossary>
*1 Bragg angle
The reflection caused by the constructive interference of X-rays irradiated to a crystal is called Bragg reflection, and the condition required for Bragg reflection is called the Bragg condition. The Bragg reflection of crystals is frequently used to extract X-rays with a single energy from synchrotron radiation, which includes X-rays with various energies. The Bragg angle is the incident angle of X-rays with respect to a crystal that satisfies the Bragg reflection condition.
*2 X-ray free-electron laser (XFEL)
An XFEL is a laser with frequencies in the X-ray region. In Japan, RIKEN, in cooperation with Japan Synchrotron Radiation Research Institute, is constructing XFEL facilities next to SPring-8. An XFEL can produce light approximately a billion times brighter than that of SPring-8, and is expected to enable the observation of the instantaneous dynamics of substances at the atomic scale.
For more information, please contact: Dr. Kei Sawada (RIKEN) |
- Current article
- Observing Drastic Translation of X-Rays by a Deformed Single Crystal - A crystal with a microscopic deformation, i.e., a disorder in the atomic arrangement, translates X-rays by the order of a millimeter. (Press Release)