Design of an Ultra-High Resolution SEM for Enhanced Analysis
The column is equipped with a well-known single-pol e bjective lens [2] that creates a strong magnetic  field around the sample, thus dramatically decreasi ng optical aberrations. Design optimization and combining the magnetic immersion field with the ele ctrostatic field [3] further improves the resolutio n to less than 1.1 nm at 1 kV. For analytical purpose s (EDS or EBSD) or for use with a FIB column however, the immersion magnetic field becomes a com plication due either to curvature of signal electron trajectories or beam splitting of ion-isot opes.
Detection Systems of Ultra-High-Resolution SEMs
For most current Scanning Electron Microscopes (SEM), the traditional Everhart-Thornley secondary electron (SE) detector and annular backscattered electron (BSE) detector are complemented with several detectors placed in the column. To choose the right system suitable for appropriate application is a challenging task. TESCAN introduced two ultra-high-resolution SEM columns [1], [2] in the last two years. Here, we present a comparison of both systems and introduce recent improvements. Both systems allow angular filtering of SE, energy-filtering of BSE and angular BSE selection.
Resonant Auger decay study of C1s -> pi* core-excited OCS
The present work aims at characterizing short-lived C1s((-1)) pi*((1)) core-excited states of the OCS molecule based on the analysis of the vibrational fine structure and lineshape profiles of the high-resolution resonant Auger decay spectra recorded at the excitation energies along the C1s -> pi* resonance in the binding energy region 15-19eV. Very different behavior in terms of lineshape and resonant enhancement is observed for the (A) over tilde, (B) over tilde and (C) over tilde final states. This is explained by (1) the variation in the C-O bond lengths for the states involved in the electronic relaxation and (2) different contributions in terms of Mulliken population to the molecular orbitals determining the electronic character of the corresponding states. Since the final-state geometries are known from a number of previous experiments and ab initio calculations, the geometry of the C1s((-1)) pi*((1)) intermediate states can be predicted in analogy with e.g. the N-2, CO2 and N2O molecules. (C) 2009 Elsevier B.V. All rights reserved. (Less)