Electromagnetic pulse produced by obliquely incident X rays

In experiments involving the exposure of targets to X-ray pulses, it commonly happens that illuminated surfaces are slanted to the incident beam, so that the arriving X rays strike the surface at an angle not equal to zero with respect to the surface normal. When this situation occurs, we show that there is generated an electromagnetic pulse emanating from the surface predominantly in the direction corresponding to specular reflection of the incident X rays. The theory of the generation of this EMP is presented. With approximations that are valid in many experimental situations, it is found that the radiated field amplitude is proportional to tangent of the incidence angle and to the normal spatial integral of the electron current density.