Bloch wave-based calculation of imaging properties of high-resolution scanning confocal electron microscopy.

An efficient, Bloch wave-based method is presented for simulation of high-resolution scanning confocal electron microscopy (SCEM) images. The latter are predicted to have coherent nature, i.e. to exhibit atomic contrast reversals depending on the lens defocus settings and sample thickness. The optimal defocus settings are suggested and the 3D imaging capabilities of SCEM are analyzed in detail. In particular, by monitoring average image intensity as a function of the probe focus depth, it should be possible to accurately measure the depth of a heavy-atom layer embedded in a light-element matrix.

Thickness measurements with electron energy loss spectroscopy.

Measurements of thickness using electron energy loss spectroscopy (EELS) are revised. Absolute thickness values can be quickly and accurately determined with the Kramers-Kronig sum method. The EELS data analysis is even much easier with the log-ratio method, however, absolute calibration of this method requires knowledge of the mean free path of inelastic electron scattering lambda. The latter has been measured here in a wide range of solids and a scaling law lambda approximately rho(-0.3) versus mass density rho has been revealed. EELS measurements critically depend on the excitation and collection angles. This dependence has been studied experimentally and theoretically and an efficient model has been formulated.

Defects in electron irradiated boron-doped diamonds investigated by positron annihilation and optical absorption.

Synthetic boron-doped single-crystal diamonds were irradiated by a pulsed electron beam at 2.2 MeV to various accumulated fluences from 0.7 × 10(18) to 10 × 10(18) e(-) cm(-2). The samples were then subjected to isochronal annealing up to 1260 °C and characterized by positron annihilation (PA) and optical absorption (OA) spectroscopies after each annealing step. PA combined with in situ monochromatic illumination gave an estimate for the positive/neutral energy level in the band gap for the monovacancy as ∼0.6 eV above the valence band-edge. From the analysis of PA and OA results, a dominant OA line at 0.552 eV was associated with a neutral boron-interstitial complex, and the annealing temperature of the positive monovacancy was deduced as ∼700 °C.

High-resolution electron microscopy of detonation nanodiamond.

The structure of individual nanodiamond grains produced by the detonation of carbon-based explosives has been studied with a high-vacuum aberration-corrected electron microscope. Many grains show a well-resolved cubic diamond lattice with negligible contamination, thereby demonstrating that the non-diamond shell, universally observed on nanodiamond particles, could be intrinsic to the preparation process rather than to the nanosized diamond itself. The strength of the adhesion between the nanodiamond grains, and the possibility of their patterning with sub-nanometer precision, are also demonstrated.