All of us have looked at leaves. They're interesting. Some of us have looked at leaves under a light microscope. Still interesting. Some have looked at leaves under more powerful microscopes, and apparently they found it interesting still. Now some folks have looked more closely than ever before, and guess what? This may be the most interesting! Wendy Mechaber, Durwood Marshall, and Frances Chew of Tufts University, Richard Mechaber of GEI Consultants, Inc., and Renee Jobe of TopoMetrix turned to the atomic force microscope (AFM) to analyze the landscape of the surfaces of leaves, apparently for the first time.

The electron microscope has evolved to the level where it is now straightforward to record high-resolution images from thin samples (t~ to 20 nm) that are directly interpretable in terms of atomic arrangements. Whilst recorded images necessarily represent two-dimensional projections of the structure, many defects such as dislocations and interfaces may be linear or planar in nature and this might be expected to be amenable to detailed characterization. In this review, we briefly consider the recent significant progress that has been made in quantitative defect analysis using the high-resolution electron microscope and then discuss some drawbacks to the technique as well as potential scope for further improvements.

Growing your own microscopy client/server image database requires addressing many issues. If you are going to grow your own, the following ideas will get you “out of the box.”

The ideal microscopy image database environment might appear like this: The core of the image database would be a very powerful, universally available, extensible, cost effective, flexible and serviceable database engine. The core engine would allow the user to perform fast and seamless SQL searches across a large database without reducing the available network bandwidth. It would be able to take advantage of current and future technologies (i.e., 64 bit processing, 1 GB networks, digital, video, multi media, etc.) The same core would be able to share information with other databases, applications and platforms. What an odd concept.

For some time now I have been studying Antony Van Leeuwenhoek's microscopes and building prototypes, and have finally settled on a design that I would like to offer to the public.

They are made of thin beaten brass, about 47 mm tall by 25 mm wide, with the lens captured between two such sheets. The subject is placed on a metal pin, adjusted with screws, to change the focus and position. One of the adjusting screws protrudes down from the body and also serves as a handle. These microscopes look very much like the one in the museum at Utrecht (circa ∼ 1690). They have a lens made of a 2 mm diameter glass ball and have a power of about 180X, with surprisingly good resolution.

This month's installment completes our primer series on magnetic fields by defining conditions where remedial EM site shielding is in fact technically feasible and by illustrating examples of both passive and active shielding methods (or attaining lower site fields. For those readers who may have missed one or more previous articles, we have thus far presented some basic physics describing magnetic source fields [Microscopy Today, November, 1995), examined magnetic survey equipment and methods relevant to EM interference thresholds (Ml, January, 1996), and, in Part IV (“Survey Data Analysis”, MT, May, 1996), suggested techniques for interpretation of typical EM site survey data.

Industrial laboratories have traditionally used 4” x 5” (100 x 125 mm) photomicrographs. Polaroid 4” x 5” prints have largely replaced glass plate and sheet film contact prints in industrial laboratories. High resolution 2000 by 3000 pixel imaging systems should be able to match the resolution of the 4” x 5” photomicrographs, typically 6 cycles per mm at a magnification of 500 times N.A., with a significantly larger field size which better utilizes modern, wide field optics. CCD cameras with 1024x 1280 pixel sensor arrays should be able to essentially match Polaroid 4” x 5“ photomicrograph prints in field size and resolution.

The Rare-Earth Laves phases RE-Fe2 (RE represent the Rare-Earth) show large magnetostrictive properties, especially at room temperature. These materials are well characterized when in bulk form, but they have rarely been studied as thin films and one can expect some important effects due to epitaxial growth.

A few single crystal layers of RE-Fe2 have been studied (YFe2, TbFe2, DyFe2, ErFe2: and Dy0.7Tb0.3Fe2 known as Terfenol-D). The thickness of these different layers are between 5 and 20 nm and with [110] as a growth direction have been epitaxied. They have been deposited with a Molecular Beam Epitaxy (MBE) in an ultra high vacuum chamber. A [1120] sapphire substrate is recovered by a [110] niobium buffer. The RE and the iron are then co-deposited on the substrate which is maintained at 500°C. Lastly, an Yttrium layer is deposited on the Rare Earth material at a temperature close to ambient.

Part 1 of this series described how focused ion beam (FIB) microsurgery is used to successfully cross-section and prepare materialspecific samples for SEM and TEM analysis. In Part 2, we detailed how FIB is also the tool of choice to prepare site-specific samples, particularly for transmission electron microscopy (TEM) analysis. In this final article of this series, we describe actual sample preparation, cutting a selected area la size and mounting it on a grid for FIB preparation. Focused ion beams are very useful in preparing TEM specimens that have unique characteristics. In particular, the ability of such systems to image submicron features within a structure has allowed accurate identification of the precise place to make a membrane.

My 9 years in industry, 5 years in academia, and 4 years as a postdoc tell me this about getting a regular (tenure-track) faculty appointment:

On a very simple level, one who wishes to be in lofty pursuits (an academic position at a research institution, where the goals are noble and the intellectual rewards are pure and at least some people respect you) would follow this conventional-wisdom paradigm:

First get a Ph.D (or MD/Ph.D), next get a postdoc, and then get an assistant “prof.” position.

Those of us who have particle identification problems sometimes have very small samples, say, only a few nanograms - even less sometimes. We also like to make up permanent Aroclor 5442 preparations of these tiny samples for safe keeping and future reference. If we mount such small samples in a normal drop of Aroclor filling an 18 mm diameter coverslip, we may spend a few frustrating minutes looking for the sample in a few acres of Aroclor. My solution is to use a very tiny Arocior droplet under a small coverslip. Ten millimeter or smaller round coverslips are available from Erie Scientific in Portsmouth, New Hampshire.

I began using scanning electron microscopes to solve problems encountered in the fabrication of x-ray diffraction gratings. Since these diffraction gratings consist of very regular lines and spaces, and produce high contrast images from the SEM. my microscopy work often points out problems with the microscope.

One time, for example, I went to the university SEM lab I often use, and was advised that the microscope was down that day due to major field problems. This lab often had problems with stray fields for reasons no one could explain. Usually I was the only one to complain about stray field distortions since they are most obvious when imaging straight lines at high magnification, but on this occasion, the problem was serious and obvious to all.

The microscope had just been serviced and as the lens coils had been replaced, they were expected to be the cause. The service technician was called in and determined that neither the coils nor the microscope electronics were the problem.