Ugo Valdrè

Impact of Electron and Scanning Probe Microscopy on Materials Research

Table of contents. Preface. Participants photos. List of Contributors. List of Participants. The impact of electron microscopy on materials research G. Thomas. Microstructural design and tayloring of advanced materials G. Thomas. Nanostructured materials V. Provenzano. Characterization of heterophase transformation interfaces by highresolution transmission electron microscope techniques J.M. Howe. High resolution scanning electron microscopy observations of nanoceramics J.Th.M. de Hosson, et al. Metal-ceramic interfaces studied with high resolution transmission electron microscopy J.Th.M. de Hosson, et al. Z-contrast scanning transmission electron microscopy S.J. Pennycook, P.D. Nellist. Electron energy loss spectrometry in the electron microscope - Part 1: Introduction L.M. Brown. Electron energy loss spectrometry in the electron microscope - Part 2: EELS in the context of solid state spectroscopies L.M. Brown. Electron energy loss spectrometry in the electron microscope - Part 3: Interfaces and localised spectrometry L.M. Brown. EELS near edge structures. Application to intermetallic alloys and other materials G.A. Botton. Surface chemistry and microstructure analysis of novel technological materials M.L. Trudeau. Convergent beam electron diffraction C.J. Humphreys. New developments in scanning probe microscopy E. Meyer, et al. Low-energy scanning electron microscope for nanolithography A. Zlatkin, N. Garcia. Application of low voltage Scanning Electron Microscopy and energy dispersive x-ray spectroscopy D.G. Rickerby. Environmental SEM and related applications. History of the environmental SEM and basic design concepts T.A. Hardt. Environmental SEM and related applications T.A. Hardt. Environmental SEM andrelated applications. Gas interactions and gaseous amplification T.A. Hardt. ESEM image contrast and applications to wet organic materials A.M. Donald, B.L. Thiel. Advanced electron and scanning probe microscopy on dental and medical materials research G. Valdre. Correlative microscopy and probing in materials science G. Valdre. Epilogue. Subject index.

Study of elastic fiber organization by scanning force microscopy.

Elastic fibers of beef ligamentum nuchae were observed by atomic force microscopy and data compared with those obtained by conventional and freeze-fracture electron microscopy. Fresh isolated elastin fibers as well as thin sections of ligament fragments, which were fixed and embedded either in relaxed or in stretched conditions, were analysed. The results confirm that, at least in beef ligamentum nuchae, elastic fibers consist of beaded filaments which can be oriented by stretching in the direction of the force applied. Moreover, atomic force microscopy revealed that these beaded filaments are laterally connected by periodical bridges which become more pronounced upon stretching. The data clearly show that elastin molecules are organized in a rather ordered array, at least at the super-molecular level, and a depiction of the elastin organization in beef ligamentum nuchae is attempted.

Electron beam ionization damage processes in p-terphenyl

Abstract Ionization damage leading to atomic displacements has been studied in crystals of p-terphenyl using low-energy electron beams. Significant damage is observed only for beam energies in excess of ∼ 1·5 keV. This can be explained on the basis that carbon K-shell ionization is the dominant process. The effective damage threshold is, however, raised well above the K-shell binding energy by competition with the valence excitation loss process.

Field Emission and Electron Microscopy.

An overview and new results are presented of the investigations carried out in the last 5 years on nano-sized tips by means of electron microscopy, an electron optical bench, and computation. Tungsten and, in particular, carbon nano-tips prepared by carbon contamination in a scanning electron microscope, were studied for applications as field-emission electron sources. Several features of their use are described and the results concerning the determination of some of their basic properties are reported.

High-resolution imaging of n-alkane crystals by atomic force microscopy

X-ray and electron crystallography of polymethylene chain compounds are known to be hindered by the very strong scattering from a dominant sublattice, and the use of high-resolution electron microscopy is severely limited by radiation damage. This study shows that these problems may be overcome by using highresolution atomic force microscopy (AFM) imaging. The work was performed on four types of linear alkane crystal, namely n-C26H54, n-C30H62, n-C36H74 and n-C44H90, of different molecular lengths. They were prepared by vapour deposition and from solution and deposited on mica and on highly oriented pyrolytic graphite. The results show that firstly AFM may complement, at a molecular and a submolecular level, the data provided by X-ray and electron crystallography, secondly alkane crystals may be prepared with different orientations and the type of substrate has no influence, and thirdly AFM may be used to induce orientational and conformational changes.

Work function dependence on the thickness and substrate of carbon contamination layers by Kelvin probe force microscopy

The contact potential difference (CPD) between carbon contamination (CC) layers and the several substrates on which they were deposited has been measured as a function of the film thickness by means of Kelvin probe force microscopy (KPFM). The observed CPD trends may be divided into three categories: i. an increase, or decrease, in CPD with thickness up to a saturation value with sign inversion with respect to the substrates (Al and Si); ii. an oscillation with no sign inversion (substrates, gold and platinum); iii. an oscillation through sign inversion (palladium substrate). Effects (ii) and (iii) seem to be typical of CC, since they have not been observed for other materials, including evaporated carbon. Several possible causes of the above two effects are examined, but a satisfactory interpretation has not been found yet. The sensitivity of KPFM is such that CC layers 10 nm thick are easily visible, whereas they are hardly detectable by topography.

Coexistence of nanoscopic domains in synthetic membranes

The coexistence in the same membrane of nanoscopic domains with different crystal structures, as predicted by molecular dynamics modelling, is here experimentally demonstrated for the first time by direct imaging. These domains have been induced in liposomes made of PLPC (1-palmitoyl-2-linoleoyl-3-phosphatidylcholine) by adding different amounts of cardiolipin (tetra-acyl-diphosphatidyl-glycerol) during preparation. It has also been found that the process of controlled lipid peroxidation deletes the lateral phase separations. All these results, obtained with atomic force microscopy, provide experimental evidence for the hydrophobic mismatch theory of lateral phase separation phenomena. The images, taken in a liquid cell, show a spatial resolution to better than 0.4 nm.

2.8 Electron Microscopy in Italy

Publisher Summary Electron Microscopy (EM) in Italy originated both in Rome at the Istituto Superiore di Saniti (ISS) under the Ministry of Health and in Bologna at the EM Center of the Physics Department under the Ministry of Public Education (now MURST, Ministry for the Universities and for Scientific and Technical Research). Some of the early users of EM worked in industrial laboratories but did not spread the EM gospel or take part in development of EM outside their own in-house applications. Hence, for the very early days of EM in Italy, one has to look at the activity of the ISS in Rome for (mainly) biomedical applications and to the EM Center of Bologna for (mainly) physics/metallurgy work. The history presented here refers essentially to the activity of the first University Center of Electron Microscopy (EM Center), which was created in the Department (formerly Institute) of Physics of Bologna.