Liquid Surface Diffractometer

The liquid surface diffractometer pictured at the Advanced Photon Source at Argonne National Laboratory

Diffractometer Photograph

Liquid Surface Reflectometer

In order to scatter from free liquid surfaces the incident as well as the scattered beams need to be manipulated.  For a fixed X-ray or neutron source, the incident beam can be prepared by a monochromator that can be tilted by angle c to tilt the beam to any desired angle with respect to the horizontal liquid surface.

The monochromator can be tilted either over an axis that is perpendicular to the incident beam or over the normal to  the Bragg reflection scattering planes. In the latter case the relation between the tilt angle chi and the angle of incidence alpha is given by:
sin(a) = l / (d sin(c))

Schematic of the liquid surface reflectometer at Ames Laboratory.
Designed by T. Herrman (Ames Lab)

Reflectometer Photograph