Observation in UniVac

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Asher Norman
5 years ago
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1 Advantages! Observation of the sample in natural state! Minimize sample destruction! Controlled evaporation! Minimize charging! LVSTD = Detection of true secondary e- Fig.: Potato starch in a tuber; low vacuum mode, 5 kv, LVSTD

2 Difficulties Destruction of the hydrated samples in the environment of the EM! Uncontrolled evaporation of the water! Instability of wet specimen under the electron beam! Charging effects How can we solve this problem? Low vacuum observation Untreated hydrated samples Cooling of the samples in the environment of SEM Dehydrate sample Fig.: Potato starch in a tuber; low vacuum mode, 5 kv, LVSTD

3 Treatment of the biological sample! Higher pressure in the chamber allows untreated or/and uncoated samples to be observed MIRA Pa VEGA Pa (optionally 2000 Pa)! Evaporation of the sample controlled using different accessories Peltier Cooling Stage and Water Vapor! Detection of different signals LVSTD detector (and/or BSE) Fig.: Potato starch in a tuber; low vacuum mode, 5 kv, LVSTD

4 Treatment of biological samples! Hydrated state! Untreated samples! Cooling Hydrated state Peltier Cooling Stage + Water Vapor Dehydrated state Chemical processing View in SEM UniVac mode

untreated samples! Samples is mounted on the stub! View in SEM, UniVac mode!

5 Untreated samples! Suitable for samples which do not contain too much water and oil Processing of untreated samples! Samples is mounted on the stub! View in SEM, UniVac mode! Detectors LVSTD detector (and/or BSE) Hydrated state Peltier Cooling Stage + Water Vapor View in SEM UniVac mode Dehydrated state Chemical processing

6 LVSTD detector! Low Vacuum Secondary electron Tescan Detector! Convenient for non-conductive samples investigation! Original design! Modified Everhart-Thornley design - patented by Tescan! True secondary electron detecting! Microlens differential barrier Fig.: Potato starch in a tuber; low vacuum mode, 5 kv, LVSTD

Cooling! Suitable for samples which cannot be treated with chemicals and drying processes! Suitable for samples which contain too much water and oil (foodstuffs, cosmetics, e.g.) Observation in Low vacuum Why Cooling in UniVac?

7 Cooling! Suitable for samples which cannot be treated with chemicals and drying processes! Suitable for samples which contain too much water and oil (foodstuffs, cosmetics, e.g.) Observation in Low vacuum Why Cooling in UniVac?! To slow down water evaporation! To control water evaporation! To minimize changes in specimen structure due to water evaporation! To minimize radiation damage Hydrated samples Peltier Cooling Stage + Water Vapor View in SEM UniVac mode Dehydrated samples Chemical fixation

Peltier Cooling Stage Observation in Low vacuum! Cooling down to -50!C! Suitable for low vacuum (as well as for high vacuum) Hydrated samples Dehydrated samples!

Automatic temperature regulation by the control software!

8 Peltier Cooling Stage Observation in Low vacuum! Cooling down to -50!C! Suitable for low vacuum (as well as for high vacuum) Hydrated samples Dehydrated samples! Based on Peltier thermoelectric effect! Maximum cooling speed 30!C/min! Automatic temperature regulation by the control software! Assembled directly in the SEM chamber Peltier Cooling Stage + Water Vapor View in SEM UniVac mode Chemical fixation!""#$%%&&&'()*+"!,)-').%/"01234

9 Peltier Cooling Stage! Evaporation of water depends on temperature and pressure Following the vapor saturation curve, swelling or shrinkage of wet samples is minimized Investigation in the environment of water vapor is suitable

10 Peltier Cooling Stage + Water Vapor an Ideal Tool for investigation of wet samples in a low vacuum mode! Allows specimen investigation in the environment of water vapor in a pressure range: of 7 Pa up to 150 Pa (MIRA3) of 7 Pa up to 500 Pa (up to 2000 Pa, VEGA 3) Saturated water vapor pressure Pressure (Pa) Temperature (!C)

11 Application examples Cell Biology Growth of Neural Progenitor Cells (RAL) on a collagen material Dilatation of the Osteoblast on different types of sintered ceramics Observation of Human Embryonic Stem Cell (HESC) colonies Immunolabeling of Human Embryonic Stem Cells - localizing particular antigens within cells Investigation of boar spermatozoa ultrastructure after thawing Microbiology Adhesion of Streptococcus mutans on the different dental filling surfaces Investigation of different Cyanobacteria colonies Botany Spore morphology of various plants

TESCAN MIRA FESEM Presentation Global Supplier of Scanning Electron Microscopes

TESCAN MIRA FESEM Presentation Global Supplier of Scanning Electron Microscopes TESCAN USA 508 Thomson Park Drive Cranberry TWP, PA 16066 Outline About TESCAN Product Portfolio MIRA FESEM Overview Electron