摘要
Two-beam and symmetric three- and four-beam grazing-incidence X-ray diffraction (GIXD) by crystals without absorption are studied based on the dynamical theory of X-ray diffraction. For two-beam cases, a new geometrical scheme is given to reveal graphically the excitation of the dispersion surface. For symmetric three- and four-beam cases, the expressions for specularly reflected and forward diffracted intensities are derived analytically. Results from the numerical calculations for the diffracted intensities, the penetration depths, the coordinates of the dispersion surface and the mode excitations are also presented for two-, three- and four-beam GIXD.