Environmental Scanning Electron Microscopy--A New Tool for Research

Submitted by Carla Browning
Phone: (907) 474-7778
03/31/03

Mention "electron microscope" to most folks and they either say "huh?" or think of high magnification pictures of really small things, involving a process that takes a lot of work to get the sample ready. That was true until fairly recently, and thanks to a generous donation by FEI Company of Hillsboro, Ore., researchers in Alaska will have access to an electron microscope that requires essentially no sample preparation.

The ElectroScan E2020 microscope is part of the University of Alaska Advanced Instrumentation Laboratory, a university-wide multi-user facility dedicated to serving imaging and x-ray needs of UAF as well as other state and national public and private researchers. Available equipment includes the ESEM, conventional SEM, electron microprobe, transmission electron microscope and two x-ray fluorescence spectrometers.

The E2020 microscope can heat or cool samples to temperatures between -195 to 500 degrees Celsius or -320 to 930 degrees Fahrenheit, allowing the observation of freezing and melting processes. The atmosphere around the sample can be altered and changes in the sample can be observed at a micro scale in real-time. It’s also equipped with a videotaping system to record the process and an x-ray spectrometer for determining elemental composition on a micron scale.

Ken Severin, director of UAF’s Advanced Instrument Lab, will give demonstrations on Friday, April 4, 2003 at 3:30 p.m. in room 201 of the Natural Sciences Facility. Severin is willing to set up appointments for media who are unable to make the 3:30- 4:30 p.m. presentation due to early deadlines. VHS tapes of samples will be available to stations who wish to include footage from the microscope in news coverage.

CONTACT: Ken Severin, Department of Geology and Geophysics, UAF (907) 474-7565 for rates, availability or other information contact Ken Severin, (907) 474-5821 or e-mail fnkps@uaf.edu.

Background:
There are two basic kinds of electron microscope those that transmit electrons through a sample and produce a shadow picture and those that work like a magnifying glass letting you look at the surface of an object up close. These are known as Scanning Electron Microscopes, or SEMs. The instrument donated to UAF is a variation of a conventional SEM, known as an environmental SEM, or ESEM.

In a conventional SEM the sample is placed under high vacuum and must be conductive. This means a sample must be 100 percent water free because water boils in a vacuum, a real problem for many, especially biological samples. The process of drying the samples is tedious, time consuming and may change the sample at the microscopic level. The process of making the sample conductive usually involves coating the sample with a thin metallic layer, something that may also alter the sample, and in some cases make it unusable for other investigations.

In an ESEM the sample is placed in a chamber much closer to normal atmospheric conditions. This means the sample can be wet. There is no tedious sample drying and less potential for sample alteration. The atmosphere in the chamber conducts the electron charge away from the sample, eliminating the need to make the sample conductive. In short, the ESEM allows a completely unprepared sample to be imaged at very high magnification, altered and viewed in real-time.

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Carla Browning
Public Information Officer
UAF University Relations
P.O. Box 757520
Fairbanks, Alaska 99775
(907) 474-7778