Preparing replica film of specimen for electron microscopy

Claim 1

A method for preparing a replica of a specimen suitable for use in transmission-type electron microscopy and which is in the form of a film comprising the steps of: (a) providing an apparatus comprising a pair of electrodes, one being an upper positive electrode and the other being a lower negative electrode which parallelly face each other with a distance therebetween and which are arranged in a vacuum vessel on a base plate, said pair of electrodes being electrically and thermically insulated from the vacuum vessel and the base plate and being surrounded by minute discharge prevention cylinders; (b) placing the specimen on the surface of the negative electrode; (c) evacuating the atmosphere within the apparatus with a vacuum pump so as to produce a high vacuum of approximately from 10 -5 to 10 -6 Torr within the apparatus; (d) introducing organic monomer vapors or a mixture thereof with a small amount of an inert or active gas into the apparatus to produce a gas pressure of approximately from 1 to 10 -2 Torr in the apparatus; (e) applying a direct discharge voltage of from 0.5 to 3 KV between said two electrodes for 1 to 15 minutes to effect a glow discharge, while the current density of the glow discharge is maintained between 0.1 and 2 mA/cm 2 by adjusting the flow rate of the organic monomer vapors to the apparatus and the flow rate of the evacuation gas from the apparatus, whereby a polymer substance film having a uniform thickness is formed on the surface of the specimen by the diffusion effect of plasma molecules; (f) removing the specimen having the polymer substance film thereon from the apparatus after putting the pressure of the atmosphere within the apparatus back to an ordinary pressure; and (g) dissolving the specimen in a solvent which does not dissolve the polymer substance film, but dissolves the specimen, to thereby separate the polymer substance film from the specimen.

Claim 2

A method for preparing a replica of a specimen suitable for use in transmission-type electron microscopy and which is in the form of a film comprising the steps of: (a) providing an apparatus comprising a pair of electrodes, one being an upper positive electrode and the other being a lower negative electrode which parallelly face each other with a distance therebetween and which are arranged in a vacuum vessel on a base plate, said pair of electrodes being electrically and thermically insulated from the vacuum vessel and the base plate and being surrounded by minute discharge prevention cylinders; (b) placing the specimen on the surface of the negative electrode; (c) evacuating the atmosphere within the apparatus with a vacuum pump so as to produce a high vacuum of approximately from 10 -5 to 10 -6 Torr within the apparatus; (d) introducing organic monomer vapors or a mixture thereof with a small amount of an inert or active gas into the apparatus to produce a gas pressure of approximately from 1 to 10 -2 Torr in the apparatus; (e) applying a direct discharge voltage of from 0.5 to 3 KV between said two electrodes for 1 to 15 minutes to effect a glow discharge, while the current density of the glow discharge is maintained between 0.1 and 2 mA/cm 2 by adjusting the flow rate of the organic monomer vapors to the apparatus and the flow rate of the evacuation gas from the apparatus, whereby a polymer substance film having a uniform thickness is formed on the surface of the specimen by the diffusion effect of plasma molecules; (f) removing the specimen having the polymer substance film thereon from the apparatus after putting the pressure of the atmosphere within the apparatus back to an ordinary pressure; and (g) dissolving the specimen in a solvent which does not dissolve the polymer substance film, but dissolves the specimen, to thereby separate the polymer substance film from the specimen.