Reducing the Missing Wedge in TEM Tomography

Abstract

This work describes a new development for extending tilt capabilities in computed tilt tomography for transmission electron microscopy (TEM) in order to reduce the missing wedge artifacts in tomographic reconstructions of nanoparticle materials. TEM samples of nanoparticles were tilted beyond the conventional limit of 70 o tilt in an aberration corrected TEM. By improving the tilting capability of conventional 3 mm TEM samples within the pole piece gap of the microscope, more information can be extracted in 3D. Tomographic tilt series of gamma () alumina catalyst support were acquired at 5 o tilt increments to a maximum tilt angular range of -85 o /+83 o (Figure 1b). Results of high visibility tilting has revealed a clear improvement in the 3D visualization of -alumina depicting crystallographic <111> faceting on the (110) surfaces of the nanoparticles. Crystallographic information parallel to the optic axis of the microscope has been improved by employing TEM tomography beyond the conventional 70 o tilt angular regime (Figure 1c). The tilt data thus obtained shows a reduction of up to 75 % in the 'missing wedge' as compared to conventional single axis (70 o