Abstract
We report that Y-shaped X-ray waveguides can be designed by utilizing the three-beam Bragg-surface diffraction geometry to generate a surface diffracted beam propagating along the direction of the waveguides. Y-shaped waveguides are prepared on a silicon wafer, choosing tantalum with the high absorbing boundary material. The forked angles of waveguides are 0.1, 0.2, 0.3, 0.4 and 0.5 degrees, respectively. The widths of waveguide are 25.6 and 1.6 micrometers. The structure of a Y-shape waveguide is examined by using the Scanning Electron Microscope (SEM). Diffraction experiments from this designed waveguide are carried out at the National Synchrotron Radiation Center (NSRRC). The Si (002)/(1-31) three-beam Bragg-surface diffraction is employed to generate the surface (1-31) diffracted beam propagating along the [110] preselected direction of the designed waveguide, where (002) is a symmetric Bragg reflection and (1-31) an asymmetric surface diffraction for the photon energy of 8.8785keV. It is found that beam splitting occurs in this Y-shaped waveguide when the forked angle between the two branches of the waveguide is smaller than two times of the critical angle of the external total reflection of Ta/Si. Also changing the azimuth angle around the [001] can lead to the adjustment of the diffracted beam intensity. We believe that the Y-shaped waveguide can be applied to the flux-switching and the flux-controlling for X-ray optics.