Specimen Preparation
Preparation of samples with large transparent areas and flat surfaces is a key element of electron microscopy. In particular, the interpretation of lattice or holographic images is often limited by the sample's geometry and surface roughness. These parameters are largely determined by a particular sample preparation procedure. The increasing demand for microscopes with a spatial resolution of better than 1Å increases the need for improved sample preparation techniques. A substantial effort at NCEM is devoted to the development of reliable and specialized thinning techniques. Current programs explore the application of chemicals to shape the surfaces of thin films, the use of nanospheres for observation of small particles, and the effect of plasma cleaning on the surfaces of samples. NCEM provides services and support for sample preparation. Three specimen preparation rooms house equipment for cutting, mechanical polishing, ion milling, and dry and wet etching, and provide supporting optical microscopes. Samples can be fully prepared on-site at the NCEM.
(Instrument schedule and requirements: Gatan 3&4: 12-12pm 12-12am; one session at a time--Cryomicrotome: 24 hours daily; 2 sessions at a time--Linda: 12-6am, 6-1pm, 1-6 pm, 6-12 am; one session at a time-- Fischione: 12-8am, 8-1 pm, 1-6pm, 6-12pm; one weekday and one evening session at time--PIPS: 12-8am, 8-1 pm, 1-6pm, 6-12pm; 2 sessions at a time.)
For more information contact: Doreen Ah Tye.
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Equipment Available for Specimen Preparation
Ultrasonic cleaner
Diamond saw (Isomet)
Polishers (Ecomet, Minimet, Handimet)
Ultrasonic disc cutter (Gatan)
3 dimplers (2 VCR, and 1 Gatan)
3 ion mills (Gatan, Fischione)
PIPS mill (Gatan)
Plasma cleaner (Fischione)
Electro-polisher (Fischione)
2 optical microscopes (Magnification up to 1000x)
2 optical stereo microscopes
Furnace (annealing in air to 200°C)
3 fume hoods for chemical polishing
South Bay IV3 ion mill with low voltage ( 0.1 - 2 kV) ion gun
Digital recording of optical micrographsCryoultramicrotome and glass knife maker
Preparation of samples with large transparent areas and flat surfaces is a key element of electron microscopy (see images below). In particular, the interpretation of lattice or holographic images is often limited by the sample's geometry and surface roughness. These parameters are largely determined by a particular sample preparation procedure. The increasing demand for microscopes with a spatial resolution of better than 0.1 nm strains the need to improve preparation techniques. It is for this reason that an increasing body of the work at NCEM is devoted to the development of reliable and specialized thinning techniques. Current programs explore the application of chemicals to shape the surfaces of thin films, and the use of nanospheres for observation of small particles or the effect of plasma cleaning on the surfaces of samples.
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Large area thinning of Si [110]. A low angle (3degree), low energy (200V) process was used. The magnification reveals the presence of the dumbbell structure at a separation of 136 pm that is present in the whole image. |
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TEM Sample Preparation Guide – an Interactive Website
A group of French researchers (Jeanne Ayache, Luc Beaunier, Jacqueline Boumendil, Gabrielle Ehret and Danièle Laub, CNRS, Paris) have created this website with practical and up-to-date information on TEM sample preparation in Materials Science, Earth Science and Biology.
The site contains an interactive educational guide comprising a database of materials that provides an automated guide to the choice of the most suitable TEM sample preparation technique based on materials properties and type of analysis. At present, the guide covers 36 sample preparation techniques with important information on the basic principle, materials, procedure, artifacts, advantages, drawbacks, as well as the specific equipment required for each technique. It has been designed to include new techniques as they are being developed.
The website also contains a database with images of different types of materials and of artifacts produced by sample preparation techniques. This image database has been designed to be interactive and will be augmented by new images of various materials from the user community.
In addition, the site maintains a calendar of events with announcements of workshops, meeting dates, special events on TEM and sample preparation techniques, and general TEM news.