X-Ray Diffraction from Surfaces and Interfaces

The low scattering cross section is the most important property of X-rays. This leads to the need for synchrotron radiation sources and is also the reason for the powerful structure determination capabilities of XRD, because in most cases the kinematical (or single) scattering theory applies. This means that the interpretation of the scattered intensity is straightforward and largely follows the methodology of bulk diffraction. 

The low scattering cross section further results in a large penetration depth. It may seem difficult to distinguish the signal from a surface if simultaneously thousands of bulk layers are scattering X-rays as well, but below we show that this is possible by making observations at the correct places in reciprocal space ( Fourier filtering ). 

Bulk diffraction is restricted to points in reciprocal space, but the two-dimensional nature of a surface or interface gives rise to rods of scattering. By observing these rods and avoiding the bulk Bragg peaks, surface-sensitive information is obtained. 

In addition, by using glancing angles of incidence, the penetration depth of X-rays can be limited and the detection of a surface signal facilitated. 

Surface arid Interface Science Concepts and Methods, First Edition. Edited by Klaus Wandelt. 

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