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Methoden und Instrumentierung Vortrag: Do., 11:30–11:50 D-V35
Hard X-Ray Microscopy based on Refractive X-Ray Lenses
Christian Schroer 1 , Jens Patommel 1 , Pit Boye 1 , Jan Feldkamp 1 , Bruno
Lengeler 2 , Manfred Burghammer 3 , Christian Riekel 3
1 Institut f. Strukturphysik, TU Dresden, D-01062 Dresden – 2 II. Physikalisches Institut,
RWTH Aachen, D-52056 Aachen – 3 ESRF, B.P. 220, F-38043 Grenoble Cedex,
France
Fig. 1: (a) nanofocusing refractive x-ray
lenses (NFLs) made of Si. (b) Hard x-ray
nanoprobe based on two crossed NFLs.
At synchrotron radiation sources, parabolic refractive
x-ray lenses allow one to built both full
field and scanning microscopes in the hard xray
range [1]. The latter microscope can be operated
in transmission, fluorescence, and diffraction
mode, giving chemical, elemental, and structural
contrast. For scanning microscopy, a small
and intensive microbeam is required. Parabolic
refractive x-ray lenses with a focal distance in
the centimeter range, so-called nanofocusing lenses
(NFLs, Fig. 1(a)), can generate hard x-ray
nanobeams in the range of 100 nm and below,
even at short distances, i. e., 40 to 70 m from the
source [2,3].
Recently, a 47nm×55nm beam with 1.7·10 8 ph/s
at 21 keV (monochromatic, Si 111) was generated
using silicon NFLs in crossed geometry
(Fig. 1(b)) at a distance of 47 m from an undulator
source (ID13) at the European Synchrotron
Radiation Facility [3]. This beam is not diffrac-
tion limited, and smaller beams may become available in the future. Lenses made
of more transparent materials, such as boron or diamond, could yield an increase in
flux of one order of magnitude and have a larger numerical aperture. For these NFLs,
diffraction limits below 20 nm are conceivable [2]. Using adiabatically focusing lenses
[4], the diffraction limit can in principle be pushed below 5 nm. The fundamental limit
to focusing with refractive optics is discussed [4].
[1] B. Lengeler, et al., J. Phys. D: Appl. Phys. 38 (2005) A218.
[2] C. G. Schroer, et al., Appl. Phys. Lett. 82 (2003) 1485.
[3] C. G. Schroer, et al., Appl. Phys. Lett. 87 (2005) 124103.
[4] C. G. Schroer, B. Lengeler, Phys. Rev. Lett. 94 (2005) 054802.