A two-dimensionally confining x-ray channel waveguide structure is combined with a high gain Kirkpatrick-Baez prefocusing mirror system yielding a hard x-ray beam with a cross section of 25 x 47 nm(2) (FWHM). Unlike the previously employed resonant beam coupling scheme, the incoming beam is coupled in from the front side of the waveguide and the waveguided beam is no longer accompanied by spurious reflected or transmitted beams. The field distribution in the waveguide channel has been calculated numerically. The calculated transmission and far-field intensity pattern are in good agreement with the experimental results.

We have investigated the x-ray scattering signal of highly aligned multilayers of the zwitterionic lipid 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine containing pores formed by the antimicrobial peptide alamethicin as a function of the peptide/lipid ratio. We are able to obtain information on the structure factor of the pore fluid, which then yields the interaction potential between pores in the plane of the bilayers. Aside from a hard core with a radius corresponding to the geometric radius of the pore, we find a repulsive lipid-mediated interaction with a range of approximately 30 A and a contact value of 2.4 k(B)T. This result is in qualitative agreement with recent theoretical models.

A hard x-ray beam of photon energy E=12.5keV has been focused by a Kirkpatrick–Baez mirror system and coupled into the front side of a single-mode x-ray waveguide. The beam dimensions of 3.8×2.5μm2 in the focus of the mirror system have thus been reduced in one direction to 32nm, corresponding to the guiding layer thickness of the waveguide. At the same time the waveguide acts as a coherence filter and leads to a well-defined intensity distribution with steep tails in the near- and far-field regions. The total flux transmitted by the waveguide exceeded 108 photons/s while no significant contributions of radiation transmitted through the absorbing waveguide cladding have been observed.

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