freeze fracture


After cryofixation the sample is transferred into a freeze etch/fracture device. In a vacuum of less than 10 -4 Pa and a temperature of – 196°C the specimen sandwich is broken out with the microtome. The random fracture face lays open the structures embedded in the ice.


The sample temperature can be varied during preparation. For the etching process it is increased to about – 100°C. With a temperature of – 196°C the microtome positioned above the sample acts as a cooling trap. The sublimation of ice lays open deeper embedded structures.



The bared fracture/etch face is coated with a 1.5 nm thick layer of Pt, Pt/C or Ta/W under a shadowing angle between 10° and 45°. A 5 nm thick carbon layer coated under 90° stabilizes these thin metal layers.


After the coating (replication) the replica is cleaned and positioned on a microscopic grid and can be analyzed in the microscope immediately.