In situ experiments in the transmission electron microscope

Abstract

The possibility of using the objective region of a transmission electron microscope as a microlaboratory has long intrigued electron microscopists. They recognised that experiments conducted on specimens inside the microscope could provide direct evidence for the way in which a material responded to a change in state or environment. Such sophisticated experiments cannot be undertaken lightly. They involve the use of special stages designed to alter the state of a specimen in a controlled and measurable way, while at the same time permitting the continuous observation of the microstructure of the material. It is the purpose of this article to review the principles and practice of in situ experimentation in both conventional 100 kV microscopes and those operating at a higher accelerating potential, to provide a practical guide to the electron microscopist.The introductory sections deal with the important question of selecting the optimum image recording technique for the process being studied, and a discussion of the factors that can affect the validity of in situ observations. A description of the design and construction of in situ stages follows and serves to highlight the ingenuity of stage designers faced with the problem of providing services to the specimen in the restricted pole-piece gap region of a microscope without compromising microscope performance. Here an attempt has been made to describe selected stages which fulfil the basic principles of good stage design and which have been successfully employed to carry out in situ experiments. Discussion is confined to the four main types of stages fulfilling the functions of heating and cooling, deformation, environmental control and Lorentz imaging. The experimental application of in situ techniques forms the major part of this review. Emphasis has been placed on investigations producing results which could not have been obtained using other techniques, such as the direct observation of the movement, multiplication and interaction of dislocations, and the development of microstructural instabilities in crystalline solids subjected to electron irradiation. This section illustrates the unique nature of the information that can be obtained both at the qualitative and quantitative level by in situ experimentation.

Dynamic electron microscopy of ATP-induced myosin head movement in living muscle thick filaments

“…Though cellular functions, such as development, growth, and differentiation, are very readily impaired by electron beam irradiation (critical electron dose, 10 Ϫ9 Ϫ10 Ϫ5 C͞cm 2 ), crystalline structures of various biomolecules are known to be resistant to much higher electron doses (5). This indicates the possibility of studying dynamic structural changes of living biomolecules in an electron microscope, using a gas environmental (hydration) chamber (EC), a device to keep the specimen in wet state in an electron microscope (5). In fact, Fukushima et al (6) recorded ATP-induced shortening of muscle myofibrils electron microscopically with the above technique, and Suda et al (7) determined the critical electron dose for the reduction of ATP-induced myofibrillar shortening to be 5 ϫ 10 Ϫ4 C͞cm 2 .…”

In situ transmission electron microscopy studies and real‐time digital imaging

“…One important aspect of in-situ studies has always been the image recording process. Traditionally, the following analogue image recording techniques have been used: (i) static images taken by photographic films, (ii) photographing the TEM screen with an externally mounted camera (cine  techniques) (Butler & Hale, 1981) and (iii) viewing the images with a TV camera and recording them onto a videotape (Butler & Hale, 1981;Vetrano et al, 1996). On the other hand, with the advent of CCD cameras and their rapid evolution for digital static imaging in TEM (Mochel et al, 1986;Kriranek et al, 1993), real-time digital imaging for in-situ experimentation has been in high demand.…”

Whys and Wherefores of Open Aperture ESTEM for in-situ Catalyst Reaction Studies

“…There is a long history of environmental facilities on older TEMs, reviewed by Butler and Hale [1], which took off scientifically at modest (nms) resolution with the HVEMs of the 1970s (Swann [2], Gai [3], and in contemporaneous TEM projects. HR ETEM came in with the purpose-built E-conversion of a then state-of-the-art Phillips CM30 HRTEM in the early 1990s (at DuPont Co, USA, Boyes and Gai [4]).…”