Towards large scale orientation mapping using the eCHORD method.

eCHORD is an alternative method for orientation mapping in Scanning Electron Microscopy that involves channeling contrast observed in BSE images. The sample tilt being small (10°), eCHORD could be a promising method for large scale maps as it limits the image deformation sometimes observed with EBSD maps. However, when the magnification is low, the scan deflection of the beam becomes important, which may modify the channeling conditions of analyzed grains, leading to orientation errors. A correction method for the resulting orientations is proposed and a resulting map on a Si single crystal is presented with an experimental misorientation of 0.12° across a field of view of 2.3 × 1.7 mm2.

Angular resolution expected from iCHORD orientation maps through a revisited ion channeling model.

Crystalline orientation maps are obtained in a Focused Ion Beam (FIB) microscope using the ion CHanneling ORientation Determination (iCHORD) method, which relies on the channeling phenomenon observed in ion-induced secondary electron images. The current paper focuses on the angular resolution that can be expected from such orientation maps, obtained using a revisited ion channeling model. A specific procedure was developed to evaluate the angular resolution, based on the distribution of orientation errors when evaluating controlled sample disorientation. The main advantage is that no external reference is required. An angular resolution of 1° is obtained on a nickel based sample using standard acquisition conditions. This value fulfills most of the needs in terms of microstructural characterization usually carried out by Electron Back Scattered Diffraction.

Electron CHanneling ORientation Determination (eCHORD): An original approach to crystalline orientation mapping.

We present a proof-of-concept attesting the feasability to obtain orientation maps of polycrystalline materials within a conventional Scanning Electron Microscope (SEM) using a standard goniometer and Back Scattered Electron (BSE) detector. The described method is based on the analysis of the contrast variation of grains due to the channeling of incident electrons on a rotating sample. On each pixel of the map, experimental intensity profiles as a function of the rotation angle are obtained and compared with simulated ones to retrieve the orientation. From first results on aluminum polycrystals, the angular resolution is estimated to be better than one degree.

On-line measurements of COD, TOC, VFA, total and partial alkalinity in anaerobic digestion processes using infra-red ectrometry.

This paper describes the use of a Fourier Transform Infra-Red (FT-IR) spectrometer as an on-line sensor to measure Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), Volatile Fatty Acids (VFA), and Partial and Total Alkalinity (PA and TA) in anaerobic digestion processes for the treatment of industrial wastewaters. Comparison with manual off-line analysis and with an on-line industrial TOC analyser and an on-line titrimetric sensor (for the measurements of VFA, TA and PA) are provided to demonstrate the interest of spectral analysis in the mid infra-red domain for the monitoring of anaerobic digestion processes. In order to further illustrate the advantages of using such a technique, on-line measurements recorded during an accident of the pH regulation in the input (pH in the reactor went above 11 and biomass activity stopped) are shown. They demonstrate that, if carefully performed, the calibration can be extended outside its range while being still compatible with requirements of wastewater treatment processes.