Dislocations are mobile at low temperatures in surprisingly many ceramics but sintering minimizes their densities. Enabling local plasticity by engineering a high dislocation density is a way to combat short cracks and toughen ceramics.

The effect of electron irradiation on aromatic thiolate selfassembled monolayers (SAMs) with oligophenyl, acene, and oligo(phenylene ethynylene) (OPE) backbones, containing from one to three phenyl rings, was studied, with emphasis on the basic irradiation-induced processes and performance of these films as negative resists in electron lithography. All films exhibited similar behavior upon the irradiation, with clear dominance of crosslinking, taking hold of the systems at already very early stages of the treatment. The cross sections for the modification of the SAM matrix and the damage of the SAM−substrate interface were determined for the primary electron energy of 50 eV, frequently used for the fabrication of carbon nanomembranes (CNM). They show only slight dependence on the backbone character as demonstrated by the example of the three-ring films. The two-ring systems exhibited the best performance as lithographic resists, with an optimal dose of 10−20 mC/cm 2 at 0.5−1 keV. The performance of the onering and three-ring systems was limited by a poor ability to form an extensive cross-linking network and by high resistance of the pristine films to the etching agents, respectively. Another process, associated with the poor lithographic performance of the threering systems but occurring at high doses for the two-ring systems as well, was a spontaneous release of the cross-linked films within the irradiated areas, in form of CNM pieces. From the lithographic data, cross sections of the irradiation-induced crosslinking were derived and discussed in context of backscattering and secondary electron yield. For the three-ring systems, fabrication of CNMs was demonstrated, for the first time in the OPE case.

This article presents an X-ray microscopy approach for mapping deeply embedded dislocations in three dimensions using a monochromatic beam with a low divergence. Magnified images are acquired by inserting an X-ray objective lens in the diffracted beam. The strain fields close to the core of dislocations give rise to scattering at angles where weak beam conditions are obtained. Analytical expressions are derived for the image contrast. While the use of the objective implies an integration over two directions in reciprocal space, scanning an aperture in the back focal plane of the microscope allows a reciprocal-space resolution of ÁQ/Q < 5 Â 10 À5 in all directions, ultimately enabling highprecision mapping of lattice strain and tilt. The approach is demonstrated on three types of samples: a multi-scale study of a large diamond crystal in transmission, magnified section topography on a 140 mm-thick SrTiO 3 sample and a reflection study of misfit dislocations in a 120 nm-thick BiFeO 3 film epitaxially grown on a thick substrate. With optimal contrast, the half-widths at half-maximum of the dislocation lines are 200 nm. A. C. Jakobsen et al. Mapping of dislocation networks 127 Figure 5Projection images of a large single-crystal diamond in the transmission experiment. (Left) Nearfield detector image with no X-ray objective and (right) corresponding dark-field image acquired with the diffraction microscope, both for À 0 = 0.002 . The magnification of the microscope is M ¼ 16:2. The direction of the rotation axis is marked by an arrow.q q 2 andq q roll are parallel to the x and y axes of these subfigures, respectively.

Dark-field X-ray microscopy is a new full-field imaging technique for nondestructively mapping the structure of deeply embedded crystalline elements in three dimensions. Placing an objective in the diffracted beam generates a magnified projection image of a local volume. By placing a detector in the back focal plane, high-resolution reciprocal space maps are generated for the local volume. Geometrical optics is used to provide analytical expressions for the resolution and range of the reciprocal space maps and the associated field of view in the sample plane. To understand the effects of coherence a comparison is made with wavefront simulations using the fractional Fourier transform. Reciprocal space mapping is demonstrated experimentally at an X-ray energy of 15.6 keV. The resolution function exhibits suppressed streaks and an FWHM resolution in all directions of ÁQ/Q = 4 Â 10 À5 or better. It is demonstrated by simulations that scanning a square aperture in the back focal plane enables strain mapping with no loss in resolution to be combined with a spatial resolution of 100 nm.